Frontiers of Physics

ISSN 2095-0462

ISSN 2095-0470(Online)

CN 11-5994/O4

2017 Impact Factor: 1.892

封面图片   2019年, 第14卷 第2期
The optomechanical system (OMS) can be used to couple the mechanical, optical, and electric degree of freedom. Although single-cavity OMS is much interesting, the integrated optomechanical systems provide a platform for on-chip optical architectures with added versatility, which may be useful in optical information processing and quantum communicat [展开] ...


2019年, 第14卷 第2期 出版日期:2019-04-15

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Logic Bell state concentration with parity check measurement
Jiu Liu, Lan Zhou, Wei Zhong, Yu-Bo Sheng
Frontiers of Physics. 2019, 14 (2): 21601-.

摘要   PDF (3241KB)

Logic qubit plays an important role in current quantum communication. In this paper, we propose an efficient entanglement concentration protocol (ECP) for a new kind of logic Bell state, where the logic qubit is the concatenated Greenber–Horne–Zeilinger (C-GHZ) state. Our ECP relies on the nondemolition polarization parity check (PPC) gates constructed with cross-Kerr nonlinearity, and can distill one pair of maximally entangled logic Bell state from two same pairs of less-entangled logic Bell states. Benefit from the nondemolition PPC gates, the concentrated maximally entangled logic Bell state can be remained for further application. Moreover, our ECP can be repeated to further concentrate the less-entangled logic Bell state. By repeating the ECP, the total success probability can be effectively increased. Based on above features, this ECP may be useful in future long-distance quantum communication.

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One-step implementation of a multi-target-qubit controlled phase gate with cat-state qubits in circuit QED
You-Ji Fan, Zhen-Fei Zheng, Yu Zhang, Dao-Ming Lu, Chui-Ping Yang
Frontiers of Physics. 2019, 14 (2): 21602-.

摘要   PDF (820KB)

We propose a single-step implementation of a muti-target-qubit controlled phase gate with one catstate qubit (cqubit) simultaneously controlling n–1 target cqubits. The two logic states of a cqubit are represented by two orthogonal cat states of a single cavity mode. In this proposal, the gate is implemented with n microwave cavities coupled to a superconducting transmon qutrit. Because the qutrit remains in the ground state during the gate operation, decoherence caused due to the qutrit’s energy relaxation and dephasing is greatly suppressed. The gate implementation is quite simple because only a single-step operation is needed and neither classical pulse nor measurement is required. Numerical simulations demonstrate that high-fidelity realization of a controlled phase gate with one cqubit simultaneously controlling two target cqubits is feasible with present circuit QED technology. This proposal can be extended to a wide range of physical systems to realize the proposed gate, such as multiple microwave or optical cavities coupled to a natural or artificial three-level atom.

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Entanglement measures of a new type pseudo-pure state in accelerated frames
Qian Dong, Ariadna J. Torres-Arenas, Guo-Hua Sun, Wen-Chao Qiang, Shi-Hai Dong
Frontiers of Physics. 2019, 14 (2): 21603-.

摘要   PDF (3909KB)

In this work we analyze the characteristics of quantum entanglement of the Dirac field in noninertial reference frames in the context of a new type pseudo-pure state, which is composed of the Bell states. This will help us to understand the relationship between the relativity and quantum information theory. Some states will be changed from entangled states into separable ones around the critical value F = 1/4, but there is no such a critical value for the variable y related to acceleration a. We find that the negativity NABI (ρTAABI) increases with F but decreases with the variable y, while the variation of the negativity NBIBII(ρTAABI) is opposite to that of the negativity NABI (ρTAABI). We also study the von Neumann entropies S(ρABI) and S(ρBIBII). We find that the S(ρABI) increases with variable y but S(ρBIBII) is independent of it. However, both S(ρABI) and S(ρBIBII) first decreases with F and then increases with it. The concurrences C(ρABI) and C(ρBIBII) are also discussed. We find that the former decreases with y while the latter increases with y but both of them first increase with F and then decrease with it.

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Optomechanical properties of a degenerate nonperiodic cavity chain
Miao-Miao Zhao, Zhuo Qian, Bang-Pin Hou, Yong Liu, Yong-Hong Zhao
Frontiers of Physics. 2019, 14 (2): 22601-.

摘要   PDF (1069KB)

The absorption of single-cavity and double-cavity optomechanical systems and periodic optomechanical lattices has previously been investigated extensively. In this paper, we present the absorption of a nonperiodic cavity chain, where the absorption value on the resonance point shows switchable dips or peaks, according to whether the optomechanical interaction is at an odd or even-numbered position in the chain. Meanwhile, the value of absorption due to the optomechanical interaction varies with the number of the bare cavities. The calculated results may have some novel applications, such as detecting the position of the movable mirror in a long cavity chain, which would be useful in quantum information processing based on optomechanical systems.

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Log-periodic quantum oscillations in topological or Dirac materials
Huichao Wang, Yanzhao Liu, Haiwen Liu, Jian Wang
Frontiers of Physics. 2019, 14 (2): 23201-.

摘要   PDF (4755KB)
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