Chinese Physics B

Guo, Meng-Li; Li, Bo; Wang, Zhi-Xi; Fei, Shao-Ming

doi: 10.1088/1674-1056/ab8e2epmid: N/A

Quantum entanglement plays essential roles in quantum information processing. The monogamy and polygamy relations characterize the entanglement distributions in the multipartite systems. We present a class of monogamy inequalities related to the μ-th power of the entanglement measure based on Rényi-α entropy, as well as polygamy relations in terms of the μ-th power of Rényi-α entanglement of assistance. These monogamy and polygamy relations are shown to be tighter than the existing ones.

Liu, Bo-Yang; Zhao, Xin; Dai, Hong-Yi; Zhang, Ming; Liao, Ying; Guo, Xiao-Feng; Gao, Wei

doi: 10.1088/1674-1056/ab8c3cpmid: N/A

To explore the influence of quantum information on the common social problem of honesty and trickery, we propose a Bayesian model for the quantum prisoners’ dilemma game. In this model, the players’ strategy formation is regarded as a negotiation of their move contract based on their types of decision policies, honesty or trickery. Although the implementation of quantum information cannot eliminate tricky players, players in our model can always end up with higher payoffs than in the classical game. For a good proportion of a credibility parameter value, a rational player will take an honest action, which is in remarkable contrast to the observation that players tend to defect in the classical prisoners’ dilemma game. This research suggests that honesty will be promoted to enhance cooperation with the assistance of quantum information resources.

Liu, Fu-Long; Yang, Wan-Sha; Wei, Ji-Hong; Wu, Di; He, Yang-Fan; Li, Yu-Chen; Ma, Tian-Li; Shen, Yang-Ping; Fan, Qi-Wen; He, Chuang-Ye; Guo, Bing; Wang, Nai-Yan

doi: 10.1088/1674-1056/ab96a0

Chen, Fu-Zhou; Cheng, Chen; Luo, Hong-Gang

doi: 10.1088/1674-1056/ab8a42pmid: N/A

We propose a new heterogeneous parallel strategy for the density matrix renormalization group (DMRG) method in the hybrid architecture with both central processing unit (CPU) and graphics processing unit (GPU). Focusing on the two most time-consuming sections in the finite DMRG sweeps, i.e., the diagonalization of superblock and the truncation of subblock, we optimize our previous hybrid algorithm to achieve better performance. For the former, we adopt OpenMP application programming interface on CPU and use our own subroutines with higher bandwidth on GPU. For the later, we use GPU to accelerate matrix and vector operations involving the reduced density matrix. Applying the parallel scheme to the Hubbard model with next-nearest hopping on the 4-leg ladder, we compute the ground state of the system and obtain the charge stripe pattern which is usually observed in high temperature superconductors. Based on simulations with different numbers of DMRG kept states, we show significant performance improvement and computational time reduction with the optimized parallel algorithm. Our hybrid parallel strategy with superiority in solving the ground state of quasi-two dimensional lattices is also expected to be useful for other DMRG applications with large numbers of kept states, e.g., the time dependent DMRG algorithms.

Duan, Liwei; Chen, Qing-Hu

doi: 10.1088/1674-1056/ab90eepmid: N/A

We study the single-photon transport in the coupled-resonator waveguide (CRW) controlled by an imperfect cavity. A Lorentzian spectrum is introduced to describe the dissipation. We find that the probability current conservation can be broken, although the imperfect cavity is a Hermitian system. The coupling strength between the imperfect cavity and the CRW has significant influences near the resonant frequency. With the increase of the coupling strength, the transmission coefficient becomes smaller. The spectral width plays a dominant role under the off-resonant condition, where the transmission coefficient is greatly suppressed with the increase of the spectral width. We also observe an abrupt jump of the transmission and reflection coefficients when the hopping amplitude is large enough. All the distinctive behaviors are closely related to the complex effective potential induced by the imperfect cavity.

Yang, Yi; Cai, Shao-Hong; Long, Zheng-Wen; Chen, Hao; Long, Chao-Yun

doi: 10.1088/1674-1056/ab888epmid: N/A

We study a two-dimensional generalized Kemmer oscillator in the cosmic string spacetime with the magnetic field to better understand the contribution from gravitational field caused by topology defects, and present the exact solutions to the generalized Kemmer equation in the cosmic string with the Morse potential and Coulomb-liked potential through using the Nikiforov–Uvarov (NU) method and biconfluent Heun equation method, respectively. Our results give the topological defect’s correction for the wave function, energy spectrum and motion equation, and show that the energy levels of the generalized Kemmer oscillator rely on the angular deficit α connected with the linear mass density m of the cosmic string and characterized the metric’s structure in the cosmic string spacetime.

Li, Xiang; Yuan, Hua-Wei; Zhang, Chun-Mei; Wang, Qin

doi: 10.1088/1674-1056/ab90f6pmid: N/A

Reference-frame-independent quantum key distribution (RFI-QKD) has been proven to be very useful and practical under realistic environment. Here, we present a scheme for one-decoy state RFI-QKD based on the work of Rusca et al. [Appl. Phys. Lett. 112, 171104 (2018)], and carry out investigation on its performance under realistic experimental conditions. Numerical simulation results show that the one-decoy state RFI-QKD can achieve comparable performance in terms of secret key rate and transmission distance as the two-decoy state correspondence under practical experimental conditions. On contrast, it does not need to prepare the vacuum state in the former case, substantially reducing the experimental complexity and random number consumptions. Therefore, our present proposal seems very promising in practical implementations of RFI-QKD.

Duan, Wei-Tao; He, Chuan; Yan, Si-Tong; Ji, Yu-Hang; Zhou, Lin; Chen, Xi; Wang, Jin; Zhan, Ming-Sheng

doi: 10.1088/1674-1056/ab969apmid: N/A

Coriolis effect is an important error source in the weak equivalence principle (WEP) test using atom interferometer. In this paper, the problem of Coriolis error in WEP test is studied theoretically and experimentally. In theoretical simulation, the Coriolis effect is analyzed by establishing an error model. The measurement errors of Eötvös coefficient (η) in WEP test related to experimental parameters, such as horizontal-velocity difference and horizontal-position difference of atomic clouds, horizontal-position difference of detectors, and rotation compensation of Raman laser’s mirror are calculated. In experimental investigation, the position difference between 85Rb and 87Rb atomic clouds is reduced to 0.1 mm by optimizing the experimental parameters, an alternating detection method is used to suppress the error caused by detection position difference, thus the Coriolis error related to the atomic clouds and detectors is reduced to 1.1× 10−9. This Coriolis error is further corrected by compensating the rotation of Raman laser’s mirror, and the total uncertainty of η measurement related to the Coriolis effect is reduced as δη = 4.4 × 10−11.

Meng, Ya; Mei, Feng; Chen, Gang; Jia, Suo-Tang

doi: 10.1088/1674-1056/ab8893pmid: N/A

We present a protocol to realize topological discrete-time quantum walks, which comprise a sequence of spin-dependent flipping displacement operations and quantum coin tossing operations, with a single trapped ion. It is demonstrated that the information of bulk topological invariants can be extracted by measuring the average projective phonon number when the walk takes place in coherent state space. Interestingly, the specific chiral symmetry owned by our discrete-time quantum walks simplifies the measuring process. Furthermore, we prove the robustness of such bulk topological invariants by introducing dynamical disorder and decoherence. Our work provides a simple method to measure bulk topological features in discrete-time quantum walks, which can be experimentally realized in the system of single trapped ions.

Wang, Li-Li; Liu, Wen-Jun

doi: 10.1088/1674-1056/ab90eapmid: N/A

A coupled (2 + 1)-dimensional variable coefficient Ginzburg–Landau equation is studied. By virtue of the modified Hirota bilinear method, the bright one-soliton solution of the equation is derived. Some phenomena of soliton propagation are analyzed by setting different dispersion terms. The influences of the corresponding parameters on the solitons are also discussed. The results can enrich the soliton theory, and may be helpful in the manufacture of optical devices.