Author: "Kafri, Dvir" / Publication Type: Reports - Searchworks@Jio Institute Digital Library Search Results

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1. Observation of disorder-free localization and efficient disorder averaging on a quantum processor

Author: Gyawali, Gaurav, Cochran, Tyler, Lensky, Yuri, Rosenberg, Eliott, Karamlou, Amir H., Kechedzhi, Kostyantyn, Berndtsson, Julia, Westerhout, Tom, Asfaw, Abraham, Abanin, Dmitry, Acharya, Rajeev, Beni, Laleh Aghababaie, Andersen, Trond I., Ansmann, Markus, Arute, Frank, Arya, Kunal, Astrakhantsev, Nikita, Atalaya, Juan, Babbush, Ryan, Ballard, Brian, Bardin, Joseph C., Bengtsson, Andreas, Bilmes, Alexander, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Browne, David A., Buchea, Brett, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Cabrera, Anthony, Campero, Juan, Chang, Hung-Shen, Chen, Zijun, Chiaro, Ben, Claes, Jahan, Cleland, Agnetta Y., Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Das, Sayan, Debroy, Dripto M., De Lorenzo, Laura, Barba, Alexander Del Toro, Demura, Sean, Di Paolo, Agustin, Donohoe, Paul, Drozdov, Ilya, Dunsworth, Andrew, Earle, Clint, Eickbusch, Alec, Elbag, Aviv Moshe, Elzouka, Mahmoud, Erickson, Catherine, Faoro, Lara, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Ganjam, Suhas, Gasca, Robert, Giang, William, Gidney, Craig, Gilboa, Dar, Gosula, Raja, Dau, Alejandro Grajales, Graumann, Dietrich, Greene, Alex, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heslin, Stephen, Heu, Paula, Hill, Gordon, Hilton, Jeremy, Hoffmann, Markus R., Huang, Hsin-Yuan, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Jordan, Stephen, Joshi, Chaitali, Juhas, Pavol, Kafri, Dvir, Kang, Hui, Khaire, Trupti, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Klimov, Paul V., Klots, Andrey R., Kobrin, Bryce, Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Kurilovich, Vladislav D., Landhuis, David, Lange-Dei, Tiano, Langley, Brandon W., Laptev, Pavel, Lau, Kim-Ming, Guevel, Loïck Le, Ledford, Justin, Lee, Joonho, Lee, Kenny, Lester, Brian J., Li, Wing Yan, Lill, Alexander T., Liu, Wayne, Livingston, William P., Locharla, Aditya, Lundahl, Daniel, Lunt, Aaron, Madhuk, Sid, Maloney, Ashley, Mandrà, Salvatore, Martin, Leigh S., Martin, Steven, Martin, Orion, Maxfield, Cameron, McClean, Jarrod R., McEwen, Matt, Meeks, Seneca, Megrant, Anthony, Mi, Xiao, Miao, Kevin C., Mieszala, Amanda, Molina, Sebastian, Montazeri, Shirin, Morvan, Alexis, Movassagh, Ramis, Neill, Charles, Nersisyan, Ani, Newman, Michael, Nguyen, Anthony, Nguyen, Murray, Ni, Chia-Hung, Niu, Murphy Yuezhen, Oliver, William D., Ottosson, Kristoffer, Pizzuto, Alex, Potter, Rebecca, Pritchard, Orion, Pryadko, Leonid P., Quintana, Chris, Reagor, Matthew J., Rhodes, David M., Roberts, Gabrielle, Rocque, Charles, Rubin, Nicholas C., Saei, Negar, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Sivak, Volodymyr, Skruzny, Jindra, Small, Spencer, Smith, W. Clarke, Springer, Sofia, Sterling, George, Suchard, Jordan, Szalay, Marco, Szasz, Aaron, Sztein, Alex, Thor, Douglas, Torunbalci, M. Mert, Vaishnav, Abeer, Vdovichev, Sergey, Vidal, Guifré, Heidweiller, Catherine Vollgraff, Waltman, Steven, Wang, Shannon X., White, Theodore, Wong, Kristi, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Ying, Bicheng, Yoo, Juhwan, Yosri, Noureldin, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobrist, Nicholas, Boixo, Sergio, Kelly, Julian, Lucero, Erik, Chen, Yu, Smelyanskiy, Vadim, Neven, Hartmut, Kovrizhin, Dmitry, Knolle, Johannes, Halimeh, Jad C., Aleiner, Igor, Moessner, Roderich, and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Strongly Correlated Electrons, High Energy Physics - Lattice
Abstract: One of the most challenging problems in the computational study of localization in quantum manybody systems is to capture the effects of rare events, which requires sampling over exponentially many disorder realizations. We implement an efficient procedure on a quantum processor, leveraging quantum parallelism, to efficiently sample over all disorder realizations. We observe localization without disorder in quantum many-body dynamics in one and two dimensions: perturbations do not diffuse even though both the generator of evolution and the initial states are fully translationally invariant. The disorder strength as well as its density can be readily tuned using the initial state. Furthermore, we demonstrate the versatility of our platform by measuring Renyi entropies. Our method could also be extended to higher moments of the physical observables and disorder learning.
Published: 2024

2. Visualizing Dynamics of Charges and Strings in (2+1)D Lattice Gauge Theories

Author: Cochran, Tyler A., Jobst, Bernhard, Rosenberg, Eliott, Lensky, Yuri D., Gyawali, Gaurav, Eassa, Norhan, Will, Melissa, Abanin, Dmitry, Acharya, Rajeev, Beni, Laleh Aghababaie, Andersen, Trond I., Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Ballard, Brian, Bardin, Joseph C., Bengtsson, Andreas, Bilmes, Alexander, Bourassa, Alexandre, Bovaird, Jenna, Broughton, Michael, Browne, David A., Buchea, Brett, Buckley, Bob B., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Cabrera, Anthony, Campero, Juan, Chang, Hung-Shen, Chen, Zijun, Chiaro, Ben, Claes, Jahan, Cleland, Agnetta Y., Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Das, Sayan, Demura, Sean, De Lorenzo, Laura, Di Paolo, Agustin, Donohoe, Paul, Drozdov, Ilya, Dunsworth, Andrew, Eickbusch, Alec, Elbag, Aviv Moshe, Elzouka, Mahmoud, Erickson, Catherine, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Ganjam, Suhas, Gasca, Robert, Genois, Élie, Giang, William, Gilboa, Dar, Gosula, Raja, Dau, Alejandro Grajales, Graumann, Dietrich, Greene, Alex, Gross, Jonathan A., Habegger, Steve, Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heu, Paula, Higgott, Oscar, Hilton, Jeremy, Huang, Hsin-Yuan, Huff, Ashley, Huggins, William J., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Joshi, Chaitali, Juhas, Pavol, Kafri, Dvir, Kang, Hui, Karamlou, Amir H., Kechedzhi, Kostyantyn, Khaire, Trupti, Khattar, Tanuj, Khezri, Mostafa, Kim, Seon, Klimov, Paul V., Kobrin, Bryce, Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Kurilovich, Vladislav D., Landhuis, David, Lange-Dei, Tiano, Langley, Brandon W., Lau, Kim-Ming, Ledford, Justin, Lee, Kenny, Lester, Brian J., Guevel, Loïck Le, Li, Wing Yan, Lill, Alexander T., Livingston, William P., Locharla, Aditya, Lundahl, Daniel, Lunt, Aaron, Madhuk, Sid, Maloney, Ashley, Mandrà, Salvatore, Martin, Leigh S., Martin, Orion, Maxfield, Cameron, McClean, Jarrod R., McEwen, Matt, Meeks, Seneca, Megrant, Anthony, Miao, Kevin C., Molavi, Reza, Molina, Sebastian, Montazeri, Shirin, Movassagh, Ramis, Neill, Charles, Newman, Michael, Nguyen, Anthony, Nguyen, Murray, Ni, Chia-Hung, Niu, Murphy Yuezhen, Oliver, William D., Ottosson, Kristoffer, Pizzuto, Alex, Potter, Rebecca, Pritchard, Orion, Quintana, Chris, Ramachandran, Ganesh, Reagor, Matthew J., Rhodes, David M., Roberts, Gabrielle, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Sivak, Volodymyr, Small, Spencer, Smith, W. Clarke, Springer, Sofia, Sterling, George, Suchard, Jordan, Szasz, Aaron, Sztein, Alex, Thor, Douglas, Torunbalci, M. Mert, Vaishnav, Abeer, Vargas, Justin, Vdovichev, Sergey, Vidal, Guifre, Heidweiller, Catherine Vollgraff, Waltman, Steven, Wang, Shannon X., Ware, Brayden, White, Theodore, Wong, Kristi, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Ying, Bicheng, Yoo, Juhwan, Yosri, Noureldin, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobris, Nicholas, Boixo, Sergio, Kelly, Julian, Lucero, Erik, Chen, Yu, Smelyanskiy, Vadim, Neven, Hartmut, Gammon-Smith, Adam, Pollmann, Frank, Knap, Michael, and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Strongly Correlated Electrons, High Energy Physics - Lattice
Abstract: Lattice gauge theories (LGTs) can be employed to understand a wide range of phenomena, from elementary particle scattering in high-energy physics to effective descriptions of many-body interactions in materials. Studying dynamical properties of emergent phases can be challenging as it requires solving many-body problems that are generally beyond perturbative limits. We investigate the dynamics of local excitations in a $\mathbb{Z}_2$ LGT using a two-dimensional lattice of superconducting qubits. We first construct a simple variational circuit which prepares low-energy states that have a large overlap with the ground state; then we create particles with local gates and simulate their quantum dynamics via a discretized time evolution. As the effective magnetic field is increased, our measurements show signatures of transitioning from deconfined to confined dynamics. For confined excitations, the magnetic field induces a tension in the string connecting them. Our method allows us to experimentally image string dynamics in a (2+1)D LGT from which we uncover two distinct regimes inside the confining phase: for weak confinement the string fluctuates strongly in the transverse direction, while for strong confinement transverse fluctuations are effectively frozen. In addition, we demonstrate a resonance condition at which dynamical string breaking is facilitated. Our LGT implementation on a quantum processor presents a novel set of techniques for investigating emergent particle and string dynamics.
Published: 2024

3. Quantum error correction below the surface code threshold

Author: Acharya, Rajeev, Aghababaie-Beni, Laleh, Aleiner, Igor, Andersen, Trond I., Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Astrakhantsev, Nikita, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Ballard, Brian, Bardin, Joseph C., Bausch, Johannes, Bengtsson, Andreas, Bilmes, Alexander, Blackwell, Sam, Boixo, Sergio, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Browne, David A., Buchea, Brett, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Cabrera, Anthony, Campero, Juan, Chang, Hung-Shen, Chen, Yu, Chen, Zijun, Chiaro, Ben, Chik, Desmond, Chou, Charina, Claes, Jahan, Cleland, Agnetta Y., Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Das, Sayan, Davies, Alex, De Lorenzo, Laura, Debroy, Dripto M., Demura, Sean, Devoret, Michel, Di Paolo, Agustin, Donohoe, Paul, Drozdov, Ilya, Dunsworth, Andrew, Earle, Clint, Edlich, Thomas, Eickbusch, Alec, Elbag, Aviv Moshe, Elzouka, Mahmoud, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Ganjam, Suhas, Garcia, Gonzalo, Gasca, Robert, Genois, Élie, Giang, William, Gidney, Craig, Gilboa, Dar, Gosula, Raja, Dau, Alejandro Grajales, Graumann, Dietrich, Greene, Alex, Gross, Jonathan A., Habegger, Steve, Hall, John, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heras, Francisco J. H., Heslin, Stephen, Heu, Paula, Higgott, Oscar, Hill, Gordon, Hilton, Jeremy, Holland, George, Hong, Sabrina, Huang, Hsin-Yuan, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Jordan, Stephen, Joshi, Chaitali, Juhas, Pavol, Kafri, Dvir, Kang, Hui, Karamlou, Amir H., Kechedzhi, Kostyantyn, Kelly, Julian, Khaire, Trupti, Khattar, Tanuj, Khezri, Mostafa, Kim, Seon, Klimov, Paul V., Klots, Andrey R., Kobrin, Bryce, Kohli, Pushmeet, Korotkov, Alexander N., Kostritsa, Fedor, Kothari, Robin, Kozlovskii, Borislav, Kreikebaum, John Mark, Kurilovich, Vladislav D., Lacroix, Nathan, Landhuis, David, Lange-Dei, Tiano, Langley, Brandon W., Laptev, Pavel, Lau, Kim-Ming, Guevel, Loïck Le, Ledford, Justin, Lee, Kenny, Lensky, Yuri D., Leon, Shannon, Lester, Brian J., Li, Wing Yan, Li, Yin, Lill, Alexander T., Liu, Wayne, Livingston, William P., Locharla, Aditya, Lucero, Erik, Lundahl, Daniel, Lunt, Aaron, Madhuk, Sid, Malone, Fionn D., Maloney, Ashley, Mandrá, Salvatore, Martin, Leigh S., Martin, Steven, Martin, Orion, Maxfield, Cameron, McClean, Jarrod R., McEwen, Matt, Meeks, Seneca, Megrant, Anthony, Mi, Xiao, Miao, Kevin C., Mieszala, Amanda, Molavi, Reza, Molina, Sebastian, Montazeri, Shirin, Morvan, Alexis, Movassagh, Ramis, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Neven, Hartmut, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Ni, Chia-Hung, O'Brien, Thomas E., Oliver, William D., Opremcak, Alex, Ottosson, Kristoffer, Petukhov, Andre, Pizzuto, Alex, Platt, John, Potter, Rebecca, Pritchard, Orion, Pryadko, Leonid P., Quintana, Chris, Ramachandran, Ganesh, Reagor, Matthew J., Rhodes, David M., Roberts, Gabrielle, Rosenberg, Eliott, Rosenfeld, Emma, Roushan, Pedram, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Senior, Andrew W., Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Singh, Shraddha, Sivak, Volodymyr, Skruzny, Jindra, Small, Spencer, Smelyanskiy, Vadim, Smith, W. Clarke, Somma, Rolando D., Springer, Sofia, Sterling, George, Strain, Doug, Suchard, Jordan, Szasz, Aaron, Sztein, Alex, Thor, Douglas, Torres, Alfredo, Torunbalci, M. Mert, Vaishnav, Abeer, Vargas, Justin, Vdovichev, Sergey, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, Waltman, Steven, Wang, Shannon X., Ware, Brayden, Weber, Kate, White, Theodore, Wong, Kristi, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Ying, Bicheng, Yoo, Juhwan, Yosri, Noureldin, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, and Zobrist, Nicholas
Subjects: Quantum Physics
Abstract: Quantum error correction provides a path to reach practical quantum computing by combining multiple physical qubits into a logical qubit, where the logical error rate is suppressed exponentially as more qubits are added. However, this exponential suppression only occurs if the physical error rate is below a critical threshold. In this work, we present two surface code memories operating below this threshold: a distance-7 code and a distance-5 code integrated with a real-time decoder. The logical error rate of our larger quantum memory is suppressed by a factor of $\Lambda$ = 2.14 $\pm$ 0.02 when increasing the code distance by two, culminating in a 101-qubit distance-7 code with 0.143% $\pm$ 0.003% error per cycle of error correction. This logical memory is also beyond break-even, exceeding its best physical qubit's lifetime by a factor of 2.4 $\pm$ 0.3. We maintain below-threshold performance when decoding in real time, achieving an average decoder latency of 63 $\mu$s at distance-5 up to a million cycles, with a cycle time of 1.1 $\mu$s. To probe the limits of our error-correction performance, we run repetition codes up to distance-29 and find that logical performance is limited by rare correlated error events occurring approximately once every hour, or 3 $\times$ 10$^9$ cycles. Our results present device performance that, if scaled, could realize the operational requirements of large scale fault-tolerant quantum algorithms., Comment: 10 pages, 4 figures, Supplementary Information
Published: 2024

4. Thermalization and Criticality on an Analog-Digital Quantum Simulator

Author: Andersen, Trond I., Astrakhantsev, Nikita, Karamlou, Amir H., Berndtsson, Julia, Motruk, Johannes, Szasz, Aaron, Gross, Jonathan A., Schuckert, Alexander, Westerhout, Tom, Zhang, Yaxing, Forati, Ebrahim, Rossi, Dario, Kobrin, Bryce, Di Paolo, Agustin, Klots, Andrey R., Drozdov, Ilya, Kurilovich, Vladislav D., Petukhov, Andre, Ioffe, Lev B., Elben, Andreas, Rath, Aniket, Vitale, Vittorio, Vermersch, Benoit, Acharya, Rajeev, Beni, Laleh Aghababaie, Anderson, Kyle, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Ballard, Brian, Bardin, Joseph C., Bengtsson, Andreas, Bilmes, Alexander, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Browne, David A., Buchea, Brett, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Cabrera, Anthony, Campero, Juan, Chang, Hung-Shen, Chen, Zijun, Chiaro, Ben, Claes, Jahan, Cleland, Agnetta Y., Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Das, Sayan, Debroy, Dripto M., De Lorenzo, Laura, Barba, Alexander Del Toro, Demura, Sean, Donohoe, Paul, Dunsworth, Andrew, Earle, Clint, Eickbusch, Alec, Elbag, Aviv Moshe, Elzouka, Mahmoud, Erickson, Catherine, Faoro, Lara, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Fowler, Austin G., Foxen, Brooks, Ganjam, Suhas, Gasca, Robert, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Graumann, Dietrich, Greene, Alex, Habegger, Steve, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heslin, Stephen, Heu, Paula, Hill, Gordon, Hoffmann, Markus R., Huang, Hsin-Yuan, Huang, Trent, Huff, Ashley, Huggins, William J., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Jordan, Stephen, Joshi, Chaitali, Juhas, Pavol, Kafri, Dvir, Kang, Hui, Kechedzhi, Kostyantyn, Khaire, Trupti, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Langley, Brandon W., Laptev, Pavel, Lau, Kim-Ming, Guevel, Loïck Le, Ledford, Justin, Lee, Joonho, Lee, Kenny, Lensky, Yuri D., Lester, Brian J., Li, Wing Yan, Lill, Alexander T., Liu, Wayne, Livingston, William P., Locharla, Aditya, Lundahl, Daniel, Lunt, Aaron, Madhuk, Sid, Maloney, Ashley, Mandrà, Salvatore, Martin, Leigh S., Martin, Orion, Martin, Steven, Maxfield, Cameron, McClean, Jarrod R., McEwen, Matt, Meeks, Seneca, Miao, Kevin C., Mieszala, Amanda, Molina, Sebastian, Montazeri, Shirin, Morvan, Alexis, Movassagh, Ramis, Neill, Charles, Nersisyan, Ani, Newman, Michael, Nguyen, Anthony, Nguyen, Murray, Ni, Chia-Hung, Niu, Murphy Yuezhen, Oliver, William D., Ottosson, Kristoffer, Pizzuto, Alex, Potter, Rebecca, Pritchard, Orion, Pryadko, Leonid P., Quintana, Chris, Reagor, Matthew J., Rhodes, David M., Roberts, Gabrielle, Rocque, Charles, Rosenberg, Eliott, Rubin, Nicholas C., Saei, Negar, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Sivak, Volodymyr, Skruzny, Jindra, Small, Spencer, Smith, W. Clarke, Springer, Sofia, Sterling, George, Suchard, Jordan, Szalay, Marco, Sztein, Alex, Thor, Douglas, Torres, Alfredo, Torunbalci, M. Mert, Vaishnav, Abeer, Vdovichev, Sergey, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, Waltman, Steven, Wang, Shannon X., White, Theodore, Wong, Kristi, Woo, Bryan W., Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Ying, Bicheng, Yoo, Juhwan, Yosri, Noureldin, Young, Grayson, Zalcman, Adam, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Hartmut, Babbush, Ryan, Boixo, Sergio, Hilton, Jeremy, Lucero, Erik, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Vidal, Guifre, Roushan, Pedram, Lauchli, Andreas M., Abanin, Dmitry A., and Mi, Xiao
Subjects: Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Strongly Correlated Electrons
Abstract: Understanding how interacting particles approach thermal equilibrium is a major challenge of quantum simulators. Unlocking the full potential of such systems toward this goal requires flexible initial state preparation, precise time evolution, and extensive probes for final state characterization. We present a quantum simulator comprising 69 superconducting qubits which supports both universal quantum gates and high-fidelity analog evolution, with performance beyond the reach of classical simulation in cross-entropy benchmarking experiments. Emulating a two-dimensional (2D) XY quantum magnet, we leverage a wide range of measurement techniques to study quantum states after ramps from an antiferromagnetic initial state. We observe signatures of the classical Kosterlitz-Thouless phase transition, as well as strong deviations from Kibble-Zurek scaling predictions attributed to the interplay between quantum and classical coarsening of the correlated domains. This interpretation is corroborated by injecting variable energy density into the initial state, which enables studying the effects of the eigenstate thermalization hypothesis (ETH) in targeted parts of the eigenspectrum. Finally, we digitally prepare the system in pairwise-entangled dimer states and image the transport of energy and vorticity during thermalization. These results establish the efficacy of superconducting analog-digital quantum processors for preparing states across many-body spectra and unveiling their thermalization dynamics.
Published: 2024

5. Incoherent Approximation of Leakage in Quantum Error Correction

Author: Marshall, Jeffrey and Kafri, Dvir
Subjects: Quantum Physics
Abstract: Quantum error correcting codes typically do not account for quantum state transitions - leakage - out of the computational subspace. Since these errors can last for multiple detection rounds they can significantly contribute to logical errors. It is therefore important to understand how to numerically model them efficiently. Fully quantum simulations of leakage require more levels per leaked qubit, which substantially limits the system sizes that may be simulated. To address this, we introduce a Random Phase Approximation (RPA) on quantum channels that preserves the incoherence between the computational and leakage subspaces. The assumption of incoherence enables the quantum simulation of leakage at little computational overhead. We motivate the approximation's validity by showing that incoherence is achieved naturally during repeated stabilizer measurements. Additionally, we provide various simulation results which show that the RPA yields accurate error correction statistics in the repetition and surface codes with physical error parameters.
Published: 2023

6. Learning to Decode the Surface Code with a Recurrent, Transformer-Based Neural Network

Author: Bausch, Johannes, Senior, Andrew W, Heras, Francisco J H, Edlich, Thomas, Davies, Alex, Newman, Michael, Jones, Cody, Satzinger, Kevin, Niu, Murphy Yuezhen, Blackwell, Sam, Holland, George, Kafri, Dvir, Atalaya, Juan, Gidney, Craig, Hassabis, Demis, Boixo, Sergio, Neven, Hartmut, and Kohli, Pushmeet
Subjects: Quantum Physics, Computer Science - Machine Learning, 81P73, 68T07, I.2.0, J.2
Abstract: Quantum error-correction is a prerequisite for reliable quantum computation. Towards this goal, we present a recurrent, transformer-based neural network which learns to decode the surface code, the leading quantum error-correction code. Our decoder outperforms state-of-the-art algorithmic decoders on real-world data from Google's Sycamore quantum processor for distance 3 and 5 surface codes. On distances up to 11, the decoder maintains its advantage on simulated data with realistic noise including cross-talk, leakage, and analog readout signals, and sustains its accuracy far beyond the 25 cycles it was trained on. Our work illustrates the ability of machine learning to go beyond human-designed algorithms by learning from data directly, highlighting machine learning as a strong contender for decoding in quantum computers.
Published: 2023

7. Measurement-induced entanglement and teleportation on a noisy quantum processor

Author: Hoke, Jesse C., Ippoliti, Matteo, Rosenberg, Eliott, Abanin, Dmitry, Acharya, Rajeev, Andersen, Trond I., Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Bardin, Joseph C., Bengtsson, Andreas, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Ben, Chik, Desmond, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Dau, Alejandro Grajales, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Di Paolo, Augustin, Drozdov, Ilya K., Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Gosula, Raja, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heu, Paula, Hoffmann, Markus R., Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Kechedzhi, Kostyantyn, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny W., Lensky, Yuri D., Lester, Brian J., Lill, Alexander T., Liu, Wayne, Locharla, Aditya, Martin, Orion, McClean, Jarrod R., McEwen, Matt, Miao, Kevin C., Mieszala, Amanda, Montazeri, Shirin, Morvan, Alexis, Movassagh, Ramis, Mruczkiewicz, Wojciech, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Newman, Michael, Ng, Jiun H., Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Tom E., Omonije, Seun, Opremcak, Alex, Petukhov, Andre, Potter, Rebecca, Pryadko, Leonid P., Quintana, Chris, Rocque, Charles, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vlad, Skruzny, Jindra, Smith, W. Clarke, Somma, Rolando D., Sterling, George, Strain, Douglas, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Ted, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie., Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Harmut, Babbush, Ryan, Bacon, Dave, Boixo, Sergio, Hilton, Jeremy, Lucero, Erik, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Mi, Xiao, Khemani, Vedika, and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Statistical Mechanics, High Energy Physics - Theory
Abstract: Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter the "arrow of time" that constrains unitary evolution. When integrated in many-body dynamics, measurements can lead to emergent patterns of quantum information in space-time that go beyond established paradigms for characterizing phases, either in or out of equilibrium. On present-day NISQ processors, the experimental realization of this physics is challenging due to noise, hardware limitations, and the stochastic nature of quantum measurement. Here we address each of these experimental challenges and investigate measurement-induced quantum information phases on up to 70 superconducting qubits. By leveraging the interchangeability of space and time, we use a duality mapping, to avoid mid-circuit measurement and access different manifestations of the underlying phases -- from entanglement scaling to measurement-induced teleportation -- in a unified way. We obtain finite-size signatures of a phase transition with a decoding protocol that correlates the experimental measurement record with classical simulation data. The phases display sharply different sensitivity to noise, which we exploit to turn an inherent hardware limitation into a useful diagnostic. Our work demonstrates an approach to realize measurement-induced physics at scales that are at the limits of current NISQ processors.
Published: 2023
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8. Overcoming leakage in scalable quantum error correction

Author: Miao, Kevin C., McEwen, Matt, Atalaya, Juan, Kafri, Dvir, Pryadko, Leonid P., Bengtsson, Andreas, Opremcak, Alex, Satzinger, Kevin J., Chen, Zijun, Klimov, Paul V., Quintana, Chris, Acharya, Rajeev, Anderson, Kyle, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Bardin, Joseph C., Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Campero, Juan, Chiaro, Ben, Collins, Roberto, Conner, Paul, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Demura, Sean, Dunsworth, Andrew, Erickson, Catherine, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Garcia, Gonzalo, Giang, William, Gidney, Craig, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Gross, Jonathan A., Hamilton, Michael C., Harrington, Sean D., Heu, Paula, Hilton, Jeremy, Hoffmann, Markus R., Hong, Sabrina, Huang, Trent, Huff, Ashley, Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kelly, Julian, Kim, Seon, Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Laws, Lily, Lee, Kenny, Lester, Brian J., Lill, Alexander T., Liu, Wayne, Locharla, Aditya, Lucero, Erik, Martin, Steven, Megrant, Anthony, Mi, Xiao, Montazeri, Shirin, Morvan, Alexis, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Potter, Rebecca, Rocque, Charles, Roushan, Pedram, Sankaragomathi, Kannan, Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Skruzny, Jindra, Smith, W. Clarke, Sterling, George, Szalay, Marco, Thor, Douglas, Torres, Alfredo, White, Theodore, Woo, Bryan W. K., Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Hartmut, Smelyanskiy, Vadim, Petukhov, Andre, Korotkov, Alexander N., Sank, Daniel, and Chen, Yu
Subjects: Quantum Physics
Abstract: Leakage of quantum information out of computational states into higher energy states represents a major challenge in the pursuit of quantum error correction (QEC). In a QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade the exponential suppression of logical error with scale, challenging the feasibility of QEC as a path towards fault-tolerant quantum computation. Here, we demonstrate the execution of a distance-3 surface code and distance-21 bit-flip code on a Sycamore quantum processor where leakage is removed from all qubits in each cycle. This shortens the lifetime of leakage and curtails its ability to spread and induce correlated errors. We report a ten-fold reduction in steady-state leakage population on the data qubits encoding the logical state and an average leakage population of less than $1 \times 10^{-3}$ throughout the entire device. The leakage removal process itself efficiently returns leakage population back to the computational basis, and adding it to a code circuit prevents leakage from inducing correlated error across cycles, restoring a fundamental assumption of QEC. With this demonstration that leakage can be contained, we resolve a key challenge for practical QEC at scale., Comment: Main text: 7 pages, 5 figures
Published: 2022
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9. Non-Abelian braiding of graph vertices in a superconducting processor

Author: Andersen, Trond I., Lensky, Yuri D., Kechedzhi, Kostyantyn, Drozdov, Ilya, Bengtsson, Andreas, Hong, Sabrina, Morvan, Alexis, Mi, Xiao, Opremcak, Alex, Acharya, Rajeev, Allen, Richard, Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Ben, Chik, Desmond, Chou, Charina, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatemi, Reza, Ferreira, Vinicius S., Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Gosula, Raja, Dau, Alejandro Grajales, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Hansen, Monica, Harrigan, Matthew P., Harrington, Sean D., Heu, Paula, Hilton, Jeremy, Hoffmann, Markus R., Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny, Lester, Brian J., Lill, Alexander, Liu, Wayne, Locharla, Aditya, Lucero, Erik, Malone, Fionn D., Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Miao, Kevin C., Mieszala, Amanda, Mohseni, Masoud, Montazeri, Shirin, Mount, Emily, Movassagh, Ramis, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Thomas E., Omonije, Seun, Petukhov, Andre, Potter, Rebecca, Pryadko, Leonid P., Quintana, Chris, Rocque, Charles, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shutty, Noah, Shvarts, Vladimir, Skruzny, Jindra, Smith, W. Clarke, Somma, Rolando, Sterling, George, Strain, Doug, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Theodore, Woo, Bryan W. K., Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Zobrist, Nicholas, Neven, Hartmut, Boixo, Sergio, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Kim, Eun-Ah, Aleiner, Igor, and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Other Condensed Matter
Abstract: Indistinguishability of particles is a fundamental principle of quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, and Abelian anyons - this principle guarantees that the braiding of identical particles leaves the system unchanged. However, in two spatial dimensions, an intriguing possibility exists: braiding of non-Abelian anyons causes rotations in a space of topologically degenerate wavefunctions. Hence, it can change the observables of the system without violating the principle of indistinguishability. Despite the well developed mathematical description of non-Abelian anyons and numerous theoretical proposals, the experimental observation of their exchange statistics has remained elusive for decades. Controllable many-body quantum states generated on quantum processors offer another path for exploring these fundamental phenomena. While efforts on conventional solid-state platforms typically involve Hamiltonian dynamics of quasi-particles, superconducting quantum processors allow for directly manipulating the many-body wavefunction via unitary gates. Building on predictions that stabilizer codes can host projective non-Abelian Ising anyons, we implement a generalized stabilizer code and unitary protocol to create and braid them. This allows us to experimentally verify the fusion rules of the anyons and braid them to realize their statistics. We then study the prospect of employing the anyons for quantum computation and utilize braiding to create an entangled state of anyons encoding three logical qubits. Our work provides new insights about non-Abelian braiding and - through the future inclusion of error correction to achieve topological protection - could open a path toward fault-tolerant quantum computing.
Published: 2022

10. Suppressing quantum errors by scaling a surface code logical qubit

Author: Acharya, Rajeev, Aleiner, Igor, Allen, Richard, Andersen, Trond I., Ansmann, Markus, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Basso, Joao, Bengtsson, Andreas, Boixo, Sergio, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Chiaro, Ben, Cogan, Josh, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatemi, Reza, Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Dau, Alejandro Grajales, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Harrigan, Matthew P., Harrington, Sean D., Higgott, Oscar, Hilton, Jeremy, Hoffmann, Markus, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Khattar, Tanuj, Khezri, Mostafa, Kieferová, Mária, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny, Lester, Brian J., Lill, Alexander, Liu, Wayne, Locharla, Aditya, Lucero, Erik, Malone, Fionn D., Marshall, Jeffrey, Martin, Orion, McClean, Jarrod R., Mccourt, Trevor, McEwen, Matt, Megrant, Anthony, Costa, Bernardo Meurer, Mi, Xiao, Miao, Kevin C., Mohseni, Masoud, Montazeri, Shirin, Morvan, Alexis, Mount, Emily, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Nersisyan, Ani, Neven, Hartmut, Newman, Michael, Ng, Jiun How, Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Thomas E., Opremcak, Alex, Platt, John, Petukhov, Andre, Potter, Rebecca, Pryadko, Leonid P., Quintana, Chris, Roushan, Pedram, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shvarts, Vladimir, Skruzny, Jindra, Smelyanskiy, Vadim, Smith, W. Clarke, Sterling, George, Strain, Doug, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Theodore, Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Young, Grayson, Zalcman, Adam, Zhang, Yaxing, and Zhu, Ningfeng
Subjects: Quantum Physics
Abstract: Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum error correction offers a path to algorithmically-relevant error rates by encoding logical qubits within many physical qubits, where increasing the number of physical qubits enhances protection against physical errors. However, introducing more qubits also increases the number of error sources, so the density of errors must be sufficiently low in order for logical performance to improve with increasing code size. Here, we report the measurement of logical qubit performance scaling across multiple code sizes, and demonstrate that our system of superconducting qubits has sufficient performance to overcome the additional errors from increasing qubit number. We find our distance-5 surface code logical qubit modestly outperforms an ensemble of distance-3 logical qubits on average, both in terms of logical error probability over 25 cycles and logical error per cycle ($2.914\%\pm 0.016\%$ compared to $3.028\%\pm 0.023\%$). To investigate damaging, low-probability error sources, we run a distance-25 repetition code and observe a $1.7\times10^{-6}$ logical error per round floor set by a single high-energy event ($1.6\times10^{-7}$ when excluding this event). We are able to accurately model our experiment, and from this model we can extract error budgets that highlight the biggest challenges for future systems. These results mark the first experimental demonstration where quantum error correction begins to improve performance with increasing qubit number, illuminating the path to reaching the logical error rates required for computation., Comment: Main text: 6 pages, 4 figures. v2: Update author list, references, Fig. S12, Table IV
Published: 2022

11. Formation of robust bound states of interacting microwave photons

Author: Morvan, Alexis, Andersen, Trond I., Mi, Xiao, Neill, Charles, Petukhov, Andre, Kechedzhi, Kostyantyn, Abanin, Dmitry, Acharya, Rajeev, Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Basso, Joao, Bengtsson, Andreas, Bortoli, Gina, Bourassa, Alexandre, Bovaird, Jenna, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burger, Tim, Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Ben, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Curtin, Ben, Debroy, Dripto M., Barba, Alexander Del Toro, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatemi, Reza, Burgos, Leslie Flores, Forati, Ebrahim, Fowler, Austin G., Foxen, Brooks, Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Dau, Alejandro Grajales, Gross, Jonathan A., Habegger, Steve, Hamilton, Michael C., Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Hoffmann, Markus, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Juhas, Pavol, Kafri, Dvir, Khattar, Tanuj, Khezri, Mostafa, Kieferova, Marika, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, John Mark, Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Laws, Lily, Lee, Joonho, Lee, Kenny, Lester, Brian J., Lill, Alexander, Liu, Wayne, Locharla, Aditya, Lucero, Erik, Malone, Fionn D., Martin, Orion, McClean, Jarrod R., McEwen, Matt, Costa, Bernardo Meurer, Miao, Kevin C., Mohseni, Masoud, Montazeri, Shirin, Mount, Emily, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Nersisyan, Ani, Newman, Michael, Nguyen, Anthony, Nguyen, Murray, Niu, Murphy Yuezhen, O'Brien, Thomas E., Olenewa, Ricardo, Opremcak, Alex, Potter, Rebecca, Quintana, Chris, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schurkus, Henry F., Schuster, Christopher, Shearn, Michael J., Shorter, Aaron, Shvarts, Vladimir, Skruzny, Jindra, Smith, W. Clarke, Sterling, George, Strain, Doug, Su, Yuan, Szalay, Marco, Torres, Alfredo, Vidal, Guifre, Villalonga, Benjamin, Heidweiller, Catherine Vollgraff, White, Theodore, Xing, Cheng, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Neven, Hartmut, Boixo, Sergio, Megrant, Anthony, Kelly, Julian, Chen, Yu, Smelyanskiy, Vadim, Aleiner, Igor, Ioffe, Lev B., and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Other Condensed Matter
Abstract: Systems of correlated particles appear in many fields of science and represent some of the most intractable puzzles in nature. The computational challenge in these systems arises when interactions become comparable to other energy scales, which makes the state of each particle depend on all other particles. The lack of general solutions for the 3-body problem and acceptable theory for strongly correlated electrons shows that our understanding of correlated systems fades when the particle number or the interaction strength increases. One of the hallmarks of interacting systems is the formation of multi-particle bound states. In a ring of 24 superconducting qubits, we develop a high fidelity parameterizable fSim gate that we use to implement the periodic quantum circuit of the spin-1/2 XXZ model, an archetypal model of interaction. By placing microwave photons in adjacent qubit sites, we study the propagation of these excitations and observe their bound nature for up to 5 photons. We devise a phase sensitive method for constructing the few-body spectrum of the bound states and extract their pseudo-charge by introducing a synthetic flux. By introducing interactions between the ring and additional qubits, we observe an unexpected resilience of the bound states to integrability breaking. This finding goes against the common wisdom that bound states in non-integrable systems are unstable when their energies overlap with the continuum spectrum. Our work provides experimental evidence for bound states of interacting photons and discovers their stability beyond the integrability limit., Comment: 7 pages + 15 pages supplements
Published: 2022
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12. Noise-resilient Edge Modes on a Chain of Superconducting Qubits

Author: Mi, Xiao, Sonner, Michael, Niu, Murphy Yuezhen, Lee, Kenneth W., Foxen, Brooks, Acharya, Rajeev, Aleiner, Igor, Andersen, Trond I., Arute, Frank, Arya, Kunal, Asfaw, Abraham, Atalaya, Juan, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Basso, Joao, Bengtsson, Andreas, Bortoli, Gina, Bourassa, Alexandre, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Benjamin, Collins, Roberto, Conner, Paul, Courtney, William, Crook, Alexander L., Debroy, Dripto M., Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Faoro, Lara, Farhi, Edward, Fatemi, Reza, Flores, Leslie, Forati, Ebrahim, Fowler, Austin G., Giang, William, Gidney, Craig, Gilboa, Dar, Giustina, Marissa, Dau, Alejandro Grajales, Gross, Jonathan A., Habegger, Steve, Harrigan, Matthew P., Hilton, Jeremy, Hoffmann, Markus, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, Lev B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kechedzhi, Kostyantyn, Khattar, Tanuj, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Klots, Andrey R., Korotkov, Alexander N., Kostritsa, Fedor, Kreikebaum, J. M., Landhuis, David, Laptev, Pavel, Lau, Kim-Ming, Lee, Joonho, Laws, Lily, Liu, Wayne, Locharla, Aditya, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McEwen, Matt, Costa, Bernardo Meurer, Miao, Kevin C., Mohseni, Masoud, Montazeri, Shirin, Morvan, Alexis, Mount, Emily, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Newman, Michael, O'Brien, Thomas E., Opremcak, Alex, Petukhov, Andre, Potter, Rebecca, Quintana, Chris, Rubin, Nicholas C., Saei, Negar, Sank, Daniel, Sankaragomathi, Kannan, Satzinger, Kevin J., Schuster, Christopher, Shearn, Michael J., Shvarts, Vladimir, Strain, Doug, Su, Yuan, Szalay, Marco, Vidal, Guifre, Villalonga, Benjamin, Vollgraff-Heidweiller, Catherine, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Zalcman, Adam, Zhang, Yaxing, Zhu, Ningfeng, Neven, Hartmut, Boixo, Sergio, Megrant, Anthony, Chen, Yu, Kelly, Julian, Smelyanskiy, Vadim, Abanin, Dmitry A., and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Other Condensed Matter
Abstract: Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing its robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model which exhibits non-local Majorana edge modes (MEMs) with $\mathbb{Z}_2$ parity symmetry. Remarkably, we find that any multi-qubit Pauli operator overlapping with the MEMs exhibits a uniform late-time decay rate comparable to single-qubit relaxation rates, irrespective of its size or composition. This characteristic allows us to accurately reconstruct the exponentially localized spatial profiles of the MEMs. Furthermore, the MEMs are found to be resilient against certain symmetry-breaking noise owing to a prethermalization mechanism. Our work elucidates the complex interplay between noise and symmetry-protected edge modes in a solid-state environment.
Published: 2022
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13. Simulations of Quantum Circuits with Approximate Noise using qsim and Cirq

Author: Isakov, Sergei V., Kafri, Dvir, Martin, Orion, Heidweiller, Catherine Vollgraff, Mruczkiewicz, Wojciech, Harrigan, Matthew P., Rubin, Nicholas C., Thomson, Ross, Broughton, Michael, Kissell, Kevin, Peters, Evan, Gustafson, Erik, Li, Andy C. Y., Lamm, Henry, Perdue, Gabriel, Ho, Alan K., Strain, Doug, and Boixo, Sergio
Subjects: Quantum Physics
Abstract: We introduce multinode quantum trajectory simulations with qsim, an open source high performance simulator of quantum circuits. qsim can be used as a backend of Cirq, a Python software library for writing quantum circuits. We present a novel delayed inner product algorithm for quantum trajectories which can result in an order of magnitude speedup for low noise simulation. We also provide tools to use this framework in Google Cloud Platform, with high performance virtual machines in a single mode or multinode setting. Multinode configurations are well suited to simulate noisy quantum circuits with quantum trajectories. Finally, we introduce an approximate noise model for Google's experimental quantum computing platform and compare the results of noisy simulations with experiments for several quantum algorithms on Google's Quantum Computing Service., Comment: 15 pages, 7 figures
Published: 2021

14. Observation of Time-Crystalline Eigenstate Order on a Quantum Processor

Author: Mi, Xiao, Ippoliti, Matteo, Quintana, Chris, Greene, Ami, Chen, Zijun, Gross, Jonathan, Arute, Frank, Arya, Kunal, Atalaya, Juan, Babbush, Ryan, Bardin, Joseph C., Basso, Joao, Bengtsson, Andreas, Bilmes, Alexander, Bourassa, Alexandre, Brill, Leon, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Debroy, Dripto, Demura, Sean, Derk, Alan R., Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Fowler, Austin G., Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Ho, Alan, Hong, Sabrina, Huang, Trent, Huff, Ashley, Huggins, William J., Ioffe, L. B., Isakov, Sergei V., Iveland, Justin, Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Khattar, Tanuj, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lee, Joonho, Lee, Kenny, Locharla, Aditya, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Miao, Kevin C., Mohseni, Masoud, Montazeri, Shirin, Mruczkiewicz, Wojciech, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Newman, Michael, Niu, Murphy Yuezhen, Brien, Thomas E. O\', Opremcak, Alex, Ostby, Eric, Pato, Balint, Petukhov, Andre, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Shvarts, Vladimir, Su, Yuan, Strain, Doug, Szalay, Marco, Trevithick, Matthew D., Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Yoo, Juhwan, Zalcman, Adam, Neven, Hartmut, Boixo, Sergio, Smelyanskiy, Vadim, Megrant, Anthony, Kelly, Julian, Chen, Yu, Sondhi, S. L., Moessner, Roderich, Kechedzhi, Kostyantyn, Khemani, Vedika, and Roushan, Pedram
Subjects: Quantum Physics, Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Statistical Mechanics, Condensed Matter - Strongly Correlated Electrons
Abstract: Quantum many-body systems display rich phase structure in their low-temperature equilibrium states. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC). Concretely, dynamical phases can be defined in periodically driven many-body localized systems via the concept of eigenstate order. In eigenstate-ordered phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, wherein few select states can mask typical behavior. Here we implement a continuous family of tunable CPHASE gates on an array of superconducting qubits to experimentally observe an eigenstate-ordered DTC. We demonstrate the characteristic spatiotemporal response of a DTC for generic initial states. Our work employs a time-reversal protocol that discriminates external decoherence from intrinsic thermalization, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. In addition, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to study non-equilibrium phases of matter on current quantum processors.
Published: 2021
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15. Exponential suppression of bit or phase flip errors with repetitive error correction

Author: Chen, Zijun, Satzinger, Kevin J., Atalaya, Juan, Korotkov, Alexander N., Dunsworth, Andrew, Sank, Daniel, Quintana, Chris, McEwen, Matt, Barends, Rami, Klimov, Paul V., Hong, Sabrina, Jones, Cody, Petukhov, Andre, Kafri, Dvir, Demura, Sean, Burkett, Brian, Gidney, Craig, Fowler, Austin G., Putterman, Harald, Aleiner, Igor, Arute, Frank, Arya, Kunal, Babbush, Ryan, Bardin, Joseph C., Bengtsson, Andreas, Bourassa, Alexandre, Broughton, Michael, Buckley, Bob B., Buell, David A., Bushnell, Nicholas, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Derk, Alan R., Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Foxen, Brooks, Giustina, Marissa, Gross, Jonathan A., Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Ho, Alan, Huang, Trent, Huggins, William J., Ioffe, L. B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Kechedzhi, Kostyantyn, Kim, Seon, Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McCourt, Trevor, Mi, Xiao, Miao, Kevin C., Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Newman, Michael, Niu, Murphy Yuezhen, O'Brien, Thomas E., Opremcak, Alex, Ostby, Eric, Pató, Bálint, Redd, Nicholas, Roushan, Pedram, Rubin, Nicholas C., Shvarts, Vladimir, Strain, Doug, Szalay, Marco, Trevithick, Matthew D., Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Neven, Hartmut, Boixo, Sergio, Smelyanskiy, Vadim, Chen, Yu, Megrant, Anthony, and Kelly, Julian
Subjects: Quantum Physics
Abstract: Realizing the potential of quantum computing will require achieving sufficiently low logical error rates. Many applications call for error rates in the $10^{-15}$ regime, but state-of-the-art quantum platforms typically have physical error rates near $10^{-3}$. Quantum error correction (QEC) promises to bridge this divide by distributing quantum logical information across many physical qubits so that errors can be detected and corrected. Logical errors are then exponentially suppressed as the number of physical qubits grows, provided that the physical error rates are below a certain threshold. QEC also requires that the errors are local and that performance is maintained over many rounds of error correction, two major outstanding experimental challenges. Here, we implement 1D repetition codes embedded in a 2D grid of superconducting qubits which demonstrate exponential suppression of bit or phase-flip errors, reducing logical error per round by more than $100\times$ when increasing the number of qubits from 5 to 21. Crucially, this error suppression is stable over 50 rounds of error correction. We also introduce a method for analyzing error correlations with high precision, and characterize the locality of errors in a device performing QEC for the first time. Finally, we perform error detection using a small 2D surface code logical qubit on the same device, and show that the results from both 1D and 2D codes agree with numerical simulations using a simple depolarizing error model. These findings demonstrate that superconducting qubits are on a viable path towards fault tolerant quantum computing.
Published: 2021
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16. Information Scrambling in Computationally Complex Quantum Circuits

Author: Mi, Xiao, Roushan, Pedram, Quintana, Chris, Mandra, Salvatore, Marshall, Jeffrey, Neill, Charles, Arute, Frank, Arya, Kunal, Atalaya, Juan, Babbush, Ryan, Bardin, Joseph C., Barends, Rami, Bengtsson, Andreas, Boixo, Sergio, Bourassa, Alexandre, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Zijun, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Demura, Sean, Derk, Alan R., Dunsworth, Andrew, Eppens, Daniel, Erickson, Catherine, Farhi, Edward, Fowler, Austin G., Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Gross, Jonathan A., Harrigan, Matthew P., Harrington, Sean D., Hilton, Jeremy, Ho, Alan, Hong, Sabrina, Huang, Trent, Huggins, William J., Ioffe, L. B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kelly, Julian, Kim, Seon, Kitaev, Alexei, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lucero, Erik, Martin, Orion, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Megrant, Anthony, Miao, Kevin C., Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Newman, Michael, Niu, Murphy Yuezhen, O'Brien, Thomas E., Opremcak, Alex, Ostby, Eric, Pato, Balint, Petukhov, Andre, Redd, Nicholas, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Shvarts, Vladimir, Strain, Doug, Szalay, Marco, Trevithick, Matthew D., Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Neven, Hartmut, Aleiner, Igor, Kechedzhi, Kostyantyn, Smelyanskiy, Vadim, and Chen, Yu
Subjects: Quantum Physics, Condensed Matter - Strongly Correlated Electrons, High Energy Physics - Theory
Abstract: Interaction in quantum systems can spread initially localized quantum information into the many degrees of freedom of the entire system. Understanding this process, known as quantum scrambling, is the key to resolving various conundrums in physics. Here, by measuring the time-dependent evolution and fluctuation of out-of-time-order correlators, we experimentally investigate the dynamics of quantum scrambling on a 53-qubit quantum processor. We engineer quantum circuits that distinguish the two mechanisms associated with quantum scrambling, operator spreading and operator entanglement, and experimentally observe their respective signatures. We show that while operator spreading is captured by an efficient classical model, operator entanglement requires exponentially scaled computational resources to simulate. These results open the path to studying complex and practically relevant physical observables with near-term quantum processors.
Published: 2021
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17. Observation of separated dynamics of charge and spin in the Fermi-Hubbard model

Author: Arute, Frank, Arya, Kunal, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Barends, Rami, Bengtsson, Andreas, Boixo, Sergio, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Chen, Yu-An, Chiaro, Ben, Collins, Roberto, Cotton, Stephen J., Courtney, William, Demura, Sean, Derk, Alan, Dunsworth, Andrew, Eppens, Daniel, Eckl, Thomas, Erickson, Catherine, Farhi, Edward, Fowler, Austin, Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Graff, Rob, Gross, Jonathan A., Habegger, Steve, Harrigan, Matthew P., Ho, Alan, Hong, Sabrina, Huang, Trent, Huggins, William, Ioffe, Lev B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Kim, Seon, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lindmark, Mike, Lucero, Erik, Marthaler, Michael, Martin, Orion, Martinis, John M., Marusczyk, Anika, McArdle, Sam, McClean, Jarrod R., McCourt, Trevor, McEwen, Matt, Megrant, Anthony, Mejuto-Zaera, Carlos, Mi, Xiao, Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Neven, Hartmut, Newman, Michael, Niu, Murphy Yuezhen, O'Brien, Thomas E., Ostby, Eric, Pató, Bálint, Petukhov, Andre, Putterman, Harald, Quintana, Chris, Reiner, Jan-Michael, Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Smelyanskiy, Vadim, Strain, Doug, Sung, Kevin J., Schmitteckert, Peter, Szalay, Marco, Tubman, Norm M., Vainsencher, Amit, White, Theodore, Vogt, Nicolas, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, and Zanker, Sebastian
Subjects: Quantum Physics
Abstract: Strongly correlated quantum systems give rise to many exotic physical phenomena, including high-temperature superconductivity. Simulating these systems on quantum computers may avoid the prohibitively high computational cost incurred in classical approaches. However, systematic errors and decoherence effects presented in current quantum devices make it difficult to achieve this. Here, we simulate the dynamics of the one-dimensional Fermi-Hubbard model using 16 qubits on a digital superconducting quantum processor. We observe separations in the spreading velocities of charge and spin densities in the highly excited regime, a regime that is beyond the conventional quasiparticle picture. To minimize systematic errors, we introduce an accurate gate calibration procedure that is fast enough to capture temporal drifts of the gate parameters. We also employ a sequence of error-mitigation techniques to reduce decoherence effects and residual systematic errors. These procedures allow us to simulate the time evolution of the model faithfully despite having over 600 two-qubit gates in our circuits. Our experiment charts a path to practical quantum simulation of strongly correlated phenomena using available quantum devices., Comment: 20 pages, 15 figures
Published: 2020

18. Quantum Approximate Optimization of Non-Planar Graph Problems on a Planar Superconducting Processor

Author: Harrigan, Matthew P., Sung, Kevin J., Neeley, Matthew, Satzinger, Kevin J., Arute, Frank, Arya, Kunal, Atalaya, Juan, Bardin, Joseph C., Barends, Rami, Boixo, Sergio, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Chiaro, Ben, Collins, Roberto, Courtney, William, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Fowler, Austin, Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Graff, Rob, Habegger, Steve, Ho, Alan, Hong, Sabrina, Huang, Trent, Ioffe, L. B., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Kim, Seon, Klimov, Paul V., Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lindmark, Mike, Leib, Martin, Martin, Orion, Martinis, John M., McClean, Jarrod R., McEwen, Matt, Megrant, Anthony, Mi, Xiao, Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neill, Charles, Neukart, Florian, Niu, Murphy Yuezhen, O'Brien, Thomas E., O'Gorman, Bryan, Ostby, Eric, Petukhov, Andre, Putterman, Harald, Quintana, Chris, Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Skolik, Andrea, Smelyanskiy, Vadim, Strain, Doug, Streif, Michael, Szalay, Marco, Vainsencher, Amit, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Zhou, Leo, Neven, Hartmut, Bacon, Dave, Lucero, Erik, Farhi, Edward, and Babbush, Ryan
Subjects: Quantum Physics
Abstract: We demonstrate the application of the Google Sycamore superconducting qubit quantum processor to combinatorial optimization problems with the quantum approximate optimization algorithm (QAOA). Like past QAOA experiments, we study performance for problems defined on the (planar) connectivity graph of our hardware; however, we also apply the QAOA to the Sherrington-Kirkpatrick model and MaxCut, both high dimensional graph problems for which the QAOA requires significant compilation. Experimental scans of the QAOA energy landscape show good agreement with theory across even the largest instances studied (23 qubits) and we are able to perform variational optimization successfully. For problems defined on our hardware graph we obtain an approximation ratio that is independent of problem size and observe, for the first time, that performance increases with circuit depth. For problems requiring compilation, performance decreases with problem size but still provides an advantage over random guessing for circuits involving several thousand gates. This behavior highlights the challenge of using near-term quantum computers to optimize problems on graphs differing from hardware connectivity. As these graphs are more representative of real world instances, our results advocate for more emphasis on such problems in the developing tradition of using the QAOA as a holistic, device-level benchmark of quantum processors., Comment: 19 pages, 15 figures
Published: 2020
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19. Hartree-Fock on a superconducting qubit quantum computer

Author: Arute, Frank, Arya, Kunal, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Barends, Rami, Boixo, Sergio, Broughton, Michael, Buckley, Bob B., Buell, David A., Burkett, Brian, Bushnell, Nicholas, Chen, Yu, Chen, Zijun, Chiaro, Benjamin, Collins, Roberto, Courtney, William, Demura, Sean, Dunsworth, Andrew, Eppens, Daniel, Farhi, Edward, Fowler, Austin, Foxen, Brooks, Gidney, Craig, Giustina, Marissa, Graff, Rob, Habegger, Steve, Harrigan, Matthew P., Ho, Alan, Hong, Sabrina, Huang, Trent, Huggins, William J., Ioffe, Lev, Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Jones, Cody, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Kim, Seon, Klimov, Paul V., Korotkov, Alexander, Kostritsa, Fedor, Landhuis, David, Laptev, Pavel, Lindmark, Mike, Lucero, Erik, Martin, Orion, Martinis, John M., McClean, Jarrod R., McEwen, Matt, Megrant, Anthony, Mi, Xiao, Mohseni, Masoud, Mruczkiewicz, Wojciech, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Neven, Hartmut, Niu, Murphy Yuezhen, O'Brien, Thomas E., Ostby, Eric, Petukhov, Andre, Putterman, Harald, Quintana, Chris, Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Smelyanskiy, Vadim, Strain, Doug, Sung, Kevin J., Szalay, Marco, Takeshita, Tyler Y., Vainsencher, Amit, White, Theodore, Wiebe, Nathan, Yao, Z. Jamie, Yeh, Ping, and Zalcman, Adam
Subjects: Quantum Physics, Physics - Chemical Physics
Abstract: As the search continues for useful applications of noisy intermediate scale quantum devices, variational simulations of fermionic systems remain one of the most promising directions. Here, we perform a series of quantum simulations of chemistry the largest of which involved a dozen qubits, 78 two-qubit gates, and 114 one-qubit gates. We model the binding energy of ${\rm H}_6$, ${\rm H}_8$, ${\rm H}_{10}$ and ${\rm H}_{12}$ chains as well as the isomerization of diazene. We also demonstrate error-mitigation strategies based on $N$-representability which dramatically improve the effective fidelity of our experiments. Our parameterized ansatz circuits realize the Givens rotation approach to non-interacting fermion evolution, which we variationally optimize to prepare the Hartree-Fock wavefunction. This ubiquitous algorithmic primitive corresponds to a rotation of the orbital basis and is required by many proposals for correlated simulations of molecules and Hubbard models. Because non-interacting fermion evolutions are classically tractable to simulate, yet still generate highly entangled states over the computational basis, we use these experiments to benchmark the performance of our hardware while establishing a foundation for scaling up more complex correlated quantum simulations of chemistry., Comment: updated link to experiment code, new version containing expanded data sets and corrected figure label
Published: 2020
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20. Supplementary information for 'Quantum supremacy using a programmable superconducting processor'

Author: Arute, Frank, Arya, Kunal, Babbush, Ryan, Bacon, Dave, Bardin, Joseph C., Barends, Rami, Biswas, Rupak, Boixo, Sergio, Brandao, Fernando G. S. L., Buell, David A., Burkett, Brian, Chen, Yu, Chen, Zijun, Chiaro, Ben, Collins, Roberto, Courtney, William, Dunsworth, Andrew, Farhi, Edward, Foxen, Brooks, Fowler, Austin, Gidney, Craig, Giustina, Marissa, Graff, Rob, Guerin, Keith, Habegger, Steve, Harrigan, Matthew P., Hartmann, Michael J., Ho, Alan, Hoffmann, Markus R., Huang, Trent, Humble, Travis S., Isakov, Sergei V., Jeffrey, Evan, Jiang, Zhang, Kafri, Dvir, Kechedzhi, Kostyantyn, Kelly, Julian, Klimov, Paul V., Knysh, Sergey, Korotkov, Alexander N., Kostritsa, Fedor, Landhuis, David, Lindmark, Mike, Lucero, Erik, Lyakh, Dmitry, Mandra, Salvatore, McClean, Jarrod R., McEwen, Matt, Megrant, Anthony, Mi, Xiao, Michielsen, Kristel, Mohseni, Masoud, Mutus, Josh, Naaman, Ofer, Neeley, Matthew, Neill, Charles, Niu, Murphy Yuezhen, Ostby, Eric, Petukhov, Andre, Platt, John C., Quintana, Chris, Rieffel, Eleanor G., Roushan, Pedram, Rubin, Nicholas C., Sank, Daniel, Satzinger, Kevin J., Smelyanskiy, Vadim, Sung, Kevin J., Trevithick, Matthew D., Vainsencher, Amit, Villalonga, Benjamin, White, Theodore, Yao, Z. Jamie, Yeh, Ping, Zalcman, Adam, Neven, Hartmut, and Martinis, John M.
Subjects: Quantum Physics
Abstract: This is an updated version of supplementary information to accompany "Quantum supremacy using a programmable superconducting processor", an article published in the October 24, 2019 issue of Nature. The main article is freely available at https://www.nature.com/articles/s41586-019-1666-5. Summary of changes since arXiv:1910.11333v1 (submitted 23 Oct 2019): added URL for qFlex source code; added Erratum section; added Figure S41 comparing statistical and total uncertainty for log and linear XEB; new References [1,65]; miscellaneous updates for clarity and style consistency; miscellaneous typographical and formatting corrections., Comment: 67 pages, 51 figures
Published: 2019
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21. Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence

Author: Quintana, C. M., Chen, Yu, Sank, D., Petukhov, A. G., White, T. C., Kafri, Dvir, Chiaro, B., Megrant, A., Barends, R., Campbell, B., Chen, Z., Dunsworth, A., Fowler, A. G., Graff, R., Jeffrey, E., Kelly, J., Lucero, E., Mutus, J. Y., Neeley, M., Neill, C., O'Malley, P. J. J., Roushan, P., Shabani, A., Smelyanskiy, V. N., Vainsencher, A., Wenner, J., Neven, H., and Martinis, John M.
Subjects: Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract: By analyzing the dissipative dynamics of a tunable gap flux qubit, we extract both sides of its two-sided environmental flux noise spectral density over a range of frequencies around $2k_BT/h \approx 1\,\rm{GHz}$, allowing for the observation of a classical-quantum crossover. Below the crossover point, the symmetric noise component follows a $1/f$ power law that matches the magnitude of the $1/f$ noise near $1\,{\rm{Hz}}$. The antisymmetric component displays a 1/T dependence below $100\,\rm{mK}$, providing dynamical evidence for a paramagnetic environment. Extrapolating the two-sided spectrum predicts the linewidth and reorganization energy of incoherent resonant tunneling between flux qubit wells., Comment: paper + supplement
Published: 2016
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22. Tunable inductive coupling of superconducting qubits in the strongly nonlinear regime

Author: Kafri, Dvir, Quintana, Chris, Chen, Yu, Shabani, Alireza, Martinis, John M., and Neven, Hartmut
Subjects: Quantum Physics
Abstract: For a variety of superconducting qubits, tunable interactions are achieved through mutual inductive coupling to a coupler circuit containing a nonlinear Josephson element. In this paper we derive the general interaction mediated by such a circuit under the Born-Oppenheimer Approximation. This interaction naturally decomposes into a classical part, with origin in the classical circuit equations, and a quantum part, associated with the coupler's zero-point energy. Our result is non-perturbative in the qubit-coupler coupling strengths and in the coupler nonlinearity. This can lead to significant departures from previous, linear theories for the inter-qubit coupling, including non-stoquastic and many-body interactions. Our analysis provides explicit and efficiently computable series for any term in the interaction Hamiltonian and can be applied to any superconducting qubit type. We conclude with a numerical investigation of our theory using a case study of two coupled flux qubits, and in particular study the regime of validity of the Born-Oppenheimer Approximation., Comment: 44 pages, 22 figures; minor revisions
Published: 2016
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23. Dynamics of an Ion Coupled to a Parametric Superconducting Circuit

Author: Kafri, Dvir, Adhikari, Prabin, and Taylor, Jacob M.
Subjects: Quantum Physics
Abstract: Superconducting circuits and trapped ions are promising architectures for quantum information processing. However, the natural frequencies for controlling these systems -- radio frequency ion control and microwave domain superconducting qubit control -- make direct Hamiltonian interactions between them weak. In this paper we describe a technique for coupling a trapped ion's motion to the fundamental mode of a superconducting circuit, by applying to the circuit a carefully modulated external magnetic flux. In conjunction with a non-linear element (Josephson junction), this gives the circuit an effective time-dependent inductance. We then show how to tune the external flux to generate a resonant coupling between the circuit and ion's motional mode, and discuss the limitations of this approach compared to using a time-dependent capacitance., Comment: 10 pages, 4 figures
Published: 2015
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24. Distinguishing Quantum and Classical Many-Body Systems

Author: Kafri, Dvir and Taylor, Jacob
Subjects: Quantum Physics
Abstract: Controllable systems relying on quantum behavior to simulate distinctly quantum models so far rely on increasingly challenging classical computing to verify their results. We develop a general protocol for confirming that an arbitrary many-body system, such as a quantum simulator, can entangle distant objects. The protocol verifies that distant qubits interacting separately with the system can become mutually entangled, and therefore serves as a local test that excitations of the system can create non-local quantum correlations. We derive an inequality analogous to Bell's inequality which can only be violated through entanglement between distant sites of the many-body system. Although our protocol is applicable to general many-body systems, it requires finding system-dependent local operations to violate the inequality. A specific example in quantum magnetism is presented., Comment: 5 pages, 2 figures
Published: 2015

25. A noise inequality for classical forces

Author: Kafri, Dvir and Taylor, J. M.
Subjects: Quantum Physics
Abstract: Lorentz invariance requires local interactions, with force laws such as the Coulomb interaction arising via virtual exchange of force carriers such as photons. Many have considered the possibility that, at long distances or large mass scales, this process changes in some way to lead to classical behavior. Here we hypothesize that classical behavior could be due to an inability of some force carriers to convey entanglement, a characteristic measure of nonlocal, quantum behavior. We then prove that there exists a local test that allows one to verify entanglement generation, falsifying our hypothesis. Crucially, we show that noise measurements can directly verify entanglement generation. This provides a step forward for a wide variety of experimental systems where traditional entanglement tests are challenging, including entanglement generation by gravity alone between macroscopic torsional oscillators., Comment: 5 pages plus appendix, 2 figures
Published: 2013

26. Algorithmic Cooling of a Quantum Simulator

Author: Kafri, Dvir and Taylor, Jacob M.
Subjects: Quantum Physics, 81P68, 81Q10
Abstract: Controlled quantum mechanical devices provide a means of simulating more complex quantum systems exponentially faster than classical computers. Such "quantum simulators" rely heavily upon being able to prepare the ground state of Hamiltonians, whose properties can be used to calculate correlation functions or even the solution to certain classical computations. While adiabatic preparation remains the primary means of producing such ground states, here we provide a different avenue of preparation: cooling to the ground state via simulated dissipation. This is in direct analogy to contemporary efforts to realize generalized forms of simulated annealing in quantum systems., Comment: 41 pages, 2 figues
Published: 2012

27. Holevo's bound from a general quantum fluctuation theorem

Author: Kafri, Dvir and Deffner, Sebastian
Subjects: Quantum Physics, Condensed Matter - Statistical Mechanics
Abstract: We give a novel derivation of Holevo's bound using an important result from nonequilibrium statistical physics, the fluctuation theorem. To do so we develop a general formalism of quantum fluctuation theorems for two-time measurements, which explicitly accounts for the back action of quantum measurements as well as possibly non-unitary time evolution. For a specific choice of observables this fluctuation theorem yields a measurement-dependent correction to the Holevo bound, leading to a tighter inequality. We conclude by analyzing equality conditions for the improved bound., Comment: 5 pages
Published: 2012
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28. Quantum Simulation of Spin Models on an Arbitrary Lattice with Trapped Ions

Author: Korenblit, Simcha, Kafri, Dvir, Campbell, Wess C., Islam, Rajibul, Edwards, Emily E., Gong, Zhe-Xuan, Lin, Guin-Dar, Duan, Luming, Kim, Jungsang, Kim, Kihwan, and Monroe, Chris
Subjects: Quantum Physics
Abstract: A collection of trapped atomic ions represents one of the most attractive platforms for the quantum simulation of interacting spin networks and quantum magnetism. Spin-dependent optical dipole forces applied to an ion crystal create long-range effective spin-spin interactions and allow the simulation of spin Hamiltonians that possess nontrivial phases and dynamics. Here we show how appropriate design of laser fields can provide for arbitrary multidimensional spin-spin interaction graphs even for the case of a linear spatial array of ions. This scheme uses currently existing trap technology and is scalable to levels where classical methods of simulation are intractable., Comment: 5 pages, 4 figures
Published: 2012
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28 results on '"Kafri, Dvir"'

1. Observation of disorder-free localization and efficient disorder averaging on a quantum processor

2. Visualizing Dynamics of Charges and Strings in (2+1)D Lattice Gauge Theories

3. Quantum error correction below the surface code threshold

4. Thermalization and Criticality on an Analog-Digital Quantum Simulator

5. Incoherent Approximation of Leakage in Quantum Error Correction

6. Learning to Decode the Surface Code with a Recurrent, Transformer-Based Neural Network

7. Measurement-induced entanglement and teleportation on a noisy quantum processor

8. Overcoming leakage in scalable quantum error correction

9. Non-Abelian braiding of graph vertices in a superconducting processor

10. Suppressing quantum errors by scaling a surface code logical qubit

11. Formation of robust bound states of interacting microwave photons

12. Noise-resilient Edge Modes on a Chain of Superconducting Qubits

13. Simulations of Quantum Circuits with Approximate Noise using qsim and Cirq

14. Observation of Time-Crystalline Eigenstate Order on a Quantum Processor

15. Exponential suppression of bit or phase flip errors with repetitive error correction

16. Information Scrambling in Computationally Complex Quantum Circuits

17. Observation of separated dynamics of charge and spin in the Fermi-Hubbard model

18. Quantum Approximate Optimization of Non-Planar Graph Problems on a Planar Superconducting Processor

19. Hartree-Fock on a superconducting qubit quantum computer

20. Supplementary information for 'Quantum supremacy using a programmable superconducting processor'

21. Observation of classical-quantum crossover of 1/f flux noise and its paramagnetic temperature dependence

22. Tunable inductive coupling of superconducting qubits in the strongly nonlinear regime

23. Dynamics of an Ion Coupled to a Parametric Superconducting Circuit

24. Distinguishing Quantum and Classical Many-Body Systems

25. A noise inequality for classical forces

26. Algorithmic Cooling of a Quantum Simulator

27. Holevo's bound from a general quantum fluctuation theorem

28. Quantum Simulation of Spin Models on an Arbitrary Lattice with Trapped Ions

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