1. Realization of high-fidelity CZ and ZZ-free iSWAP gates with a tunable coupler
- Author
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Sung, Youngkyu, Ding, Leon, Braumüller, Jochen, Vepsäläinen, Antti, Kannan, Bharath, Kjaergaard, Morten, Greene, Ami, Samach, Gabriel O., McNally, Chris, Kim, David, Melville, Alexander, Niedzielski, Bethany M., Schwartz, Mollie E., Yoder, Jonilyn L., Orlando, Terry P., Gustavsson, Simon, and Oliver, William D.
- Subjects
Quantum Physics - Abstract
High-fidelity two-qubit gates at scale are a key requirement to realize the full promise of quantum computation and simulation. The advent and use of coupler elements to tunably control two-qubit interactions has improved operational fidelity in many-qubit systems by reducing parasitic coupling and frequency crowding issues. Nonetheless, two-qubit gate errors still limit the capability of near-term quantum applications. The reason, in part, is the existing framework for tunable couplers based on the dispersive approximation does not fully incorporate three-body multi-level dynamics, which is essential for addressing coherent leakage to the coupler and parasitic longitudinal ($ZZ$) interactions during two-qubit gates. Here, we present a systematic approach that goes beyond the dispersive approximation to exploit the engineered level structure of the coupler and optimize its control. Using this approach, we experimentally demonstrate CZ and $ZZ$-free iSWAP gates with two-qubit interaction fidelities of $99.76 \pm 0.07$% and $99.87 \pm 0.23$%, respectively, which are close to their $T_1$ limits., Comment: 34 pages, 39 figures
- Published
- 2020
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