9 results on '"Chuan-Feng Li"'
Search Results
2. Taking tomographic measurements for photonic qubits 88 ns before they are created*
- Author
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Guo-Yong Xiang, Chao Zhang, Chuan-Feng Li, Guang-Can Guo, Anthony Laing, Geoff J. Pryde, Han-Sen Zhong, Zhibo Hou, and Qi Yin
- Subjects
Physics ,Quantum Physics ,Process tomography ,Photon ,business.industry ,FOS: Physical sciences ,General Physics and Astronomy ,02 engineering and technology ,Quantum channel ,021001 nanoscience & nanotechnology ,01 natural sciences ,Teleportation ,Computational physics ,Qubit ,0103 physical sciences ,Tomography ,Photonics ,Quantum Physics (quant-ph) ,010306 general physics ,0210 nano-technology ,business ,Quantum teleportation - Abstract
We experimentally demonstrate that tomographic measurements can be performed for states of qubits before they are prepared. A variant of the quantum teleportation protocol is used as a channel between two instants in time, allowing measurements for polarisation states of photons to be implemented 88 ns before they are created. Measurement data taken at the early time and later unscrambled according to the results of the protocol's Bell measurements, produces density matrices with an average fidelity of $0.90 \pm 0.01$ against the ideal states of photons created at the later time. Process tomography of the time-reverse quantum channel finds an average process fidelity of $0.84 \pm 0.02$. While our proof-of-principle implementation necessitates some post-selection, the general protocol is deterministic and requires no post-selection to sift desired states and reject a larger ensemble., Comments welcome
- Published
- 2021
3. Detection and quantification of entanglement with measurement-device-independent and universal entanglement witness*
- Author
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Zhi-Jin Ke, Chuan-Feng Li, Jin-Shi Xu, Yi-Tao Wang, Wei Liu, Jian-Shun Tang, Shang Yu, Guang-Can Guo, Qiang Li, Hang Wang, Ya Xiao, Zhi-Peng Li, and Yu Meng
- Subjects
Computer science ,General Physics and Astronomy ,Concurrence ,02 engineering and technology ,State (functional analysis) ,Quantum entanglement ,021001 nanoscience & nanotechnology ,01 natural sciences ,Measure (mathematics) ,Outcome (probability) ,0103 physical sciences ,Quantum system ,Bipartite graph ,Statistical physics ,010306 general physics ,0210 nano-technology ,Entanglement witness - Abstract
Entanglement is the key resource in quantum information processing, and an entanglement witness (EW) is designed to detect whether a quantum system has any entanglement. However, prior knowledge of the target states should be known first to design a suitable EW, which weakens this method. Nevertheless, a recent theory shows that it is possible to design a universal entanglement witness (UEW) to detect negative-partial-transpose (NPT) entanglement in unknown bipartite states with measurement-device-independent (MDI) characteristic. The outcome of a UEW can also be upgraded to be an entanglement measure. In this study, we experimentally design and realize an MDI UEW for two-qubit entangled states. All of the tested states are well-detected without any prior knowledge. We also show that it is able to quantify entanglement by comparing it with concurrence estimated through state tomography. The relation between them is also revealed. The entire experimental framework ensures that the UEW is MDI.
- Published
- 2020
4. Experimental demonstration of tight duality relation in three-path interferometer*
- Author
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Wei Liu, Jian-Shun Tang, Hang Wang, Shang Yu, Zhi-Jin Ke, Zhi-Peng Li, Yu Meng, Qiang Li, Jin-Shi Xu, Guo Guang-Can, Yi-Tao Wang, and Chuan-Feng Li
- Subjects
Physics ,Interferometry ,Path (graph theory) ,General Physics and Astronomy ,Topology ,Duality relation - Abstract
Bohr’s principle of complementarity has a long history and it is an important topic in quantum theory, among which the famous example is the duality relation. The relation between visibility C and distinguishability D, C 2 + D 2 ≤ 1 , has long been recognized as the only representative of the duality relation. However, recent researches have shown that this inequality is not good enough because it is not tight for multipath interferometers. Meanwhile, a tight bound for the multipath interferometer has been put forward. Here we design and experimentally implement a three-path interferometer coupling with path indicator states. The wave property of photons is characterized by l 1-norm coherence measure, and the particle property is based on distinguishability of the indicator states. The new duality relation of the three-path interferometer is demonstrated in our experiment, which bounds the union of a right triangle and a part of elliptical area inside the quadrant of a unit circle. Data analysis confirms that the new bound is tight for photons in three-path interferometers.
- Published
- 2020
5. Dipole–dipole interactions enhance non-Markovianity and protect information against dissipation*
- Author
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Chuan-Feng Li, Munsif Jan, Yong-Jian Han, Qin-Qin Wang, Zhe Chen, Xiao-Ye Xu, and Guang-Can Guo
- Subjects
Physics ,Quantum decoherence ,Computer Science::Information Retrieval ,General Physics and Astronomy ,Markov process ,02 engineering and technology ,Quantum entanglement ,Dissipation ,021001 nanoscience & nanotechnology ,Quantum information processing ,01 natural sciences ,symbols.namesake ,Dipole ,0103 physical sciences ,symbols ,Statistical physics ,010306 general physics ,0210 nano-technology ,Amplitude damping channel ,Coherence (physics) - Abstract
Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies. In this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping channel. We also consider dipole-dipole interactions (DDIs) between the system and ancilla, which are responsible for strong correlations. We investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different environments. We show that DDIs are not only better than detuning at protecting the information (without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian dynamics. In contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian dynamics. In addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing detuning. We also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information.
- Published
- 2019
6. Quantum light storage in rare-earth-ion-doped solids
- Author
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Chuan-Feng Li, Zong-Quan Zhou, Yi-Lin Hua, and Guang-Can Guo
- Subjects
Physics ,Rare earth ,Doping ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,Ion ,Light storage ,0103 physical sciences ,Atomic physics ,010306 general physics ,0210 nano-technology ,Quantum - Published
- 2018
7. Linear optical approach to supersymmetric dynamics.
- Author
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Yong-Tao Zhan, Xiao-Ye Xu, Qin-Qin Wang, Wei-Wei Pan, Munsif Jan, Fu-Ming Chang, Kai Sun, Jin-Shi Xu, Yong-Jian Han, Chuan-Feng Li, and Guang-Can Guo
- Subjects
PARTICLE physics ,QUANTUM mechanics ,OPTICS ,SUPERSYMMETRY ,PHYSICS ,UNITARY operators ,OPTICAL diffraction - Abstract
The concept of supersymmetry developed in particle physics has been applied to various fields of modern physics. In quantum mechanics, the supersymmetric systems refer to the systems involving two supersymmetric partner Hamiltonians, whose energy levels are degeneracy except one of the systems has an extra ground state possibly, and the eigenstates of the partner systems can be mapped onto each other. Recently, an interferometric scheme has been proposed to show this relationship in ultracold atoms [Phys. Rev. A96 043624 (2017)]. Here this approach is generalized to linear optics for observing the supersymmetric dynamics with photons. The time evolution operator is simulated approximately via Suzuki–Trotter expansion with considering the realization of the kinetic and potential terms separately. The former is realized through the diffraction nature of light and the later is implemented using a phase plate. Additionally, we propose an interferometric approach which can be implemented perfectly using an amplitude alternator to realize the non-unitary operator. The numerical results show that our scheme is universal and can be realized with current technologies. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
8. Dipole–dipole interactions enhance non-Markovianity and protect information against dissipation.
- Author
-
Munsif Jan, Xiao-Ye Xu, Qin-Qin Wang, Zhe Chen, Yong-Jian Han, Chuan-Feng Li, and Guang-Can Guo
- Subjects
DIPOLE-dipole interactions ,QUANTUM entanglement ,INFORMATION sharing ,INFORMATION technology - Abstract
Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing technologies. In this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping channel. We also consider dipole-dipole interactions (DDIs) between the system and ancilla, which are responsible for strong correlations. We investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different environments. We show that DDIs are not only better than detuning at protecting the information (without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian dynamics. In contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian dynamics. In addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing detuning. We also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
9. Quantum light storage in rare-earth-ion-doped solids.
- Author
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Yi-Lin Hua, Zong-Quan Zhou, Chuan-Feng Li, and Guang-Can Guo
- Subjects
QUANTUM theory ,QUANTUM networks (Optics) ,QUANTUM states ,QUANTUM information science ,PHOTONS - Abstract
The reversible transfer of unknown quantum states between light and matter is essential for constructing large-scale quantum networks. Over the last decade, various physical systems have been proposed to realize such quantum memory for light. The solid-state quantum memory based on rare-earth-ion-doped solids has the advantages of a reduced setup complexity and high robustness for scalable application. We describe the methods used to spectrally prepare the quantum memory and release the photonic excitation on-demand. We will review the state of the art experiments and discuss the perspective applications of this particular system in both quantum information science and fundamental tests of quantum physics. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
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