arXiv subjects

Ye-Qi Zhang

Publications and source records attributed to Ye-Qi Zhang.

6 recordsLinked to original sources

arXiv2024

The transfer of nonlocality between two- and three-qubit dissipative systems with counter-rotating-wave terms

We investigate the effect of counter-rotating-wave terms on nonlocality and entanglement for three qubits coupled with a common bath for strong and ultrastrong coupling regimes beyond the traditional treatment of Born-Markovian, perturbative and rotating wave approximations by employing the numerical hierarchical equations of motion approach. Our findings are as follows: (i) In the strong coupling regime, the counter-rotating terms accelerate the decay of genuine three-party correlations, and the obvious sudden birth of BN is found; (ii) In the ultrastrong coupling regime, we observe a novel phenomenon where nonlocality is consistently transferred between a three-qubit and its subsystem. Besides, the inclusion of counter-rotating wave terms obviously enhances genuine tripartite nonlocality; and (iii) These counter-rotating terms cannot effectively generate genuine three-party correlations in zero-excitation cases, which differs from previous studies involving only two qubits.

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arXiv2024

Quantum Zeno Effect on Genuine Tripartite Nonlocality and Entanglement in Quantum Dissipative System

As a precious global resource in quantum information, genuine tripartite nonlocality(GTN) can be quantified by violating Svetlichny inequality. However, there is still no analytical expression for the general three-qubit states due to the difficulty of theoretical calculations. In this paper, we achieve highly accurate quantization of GTN for arbitrary three-qubit quantum states numerically. As an example, we study the dynamics of GTN and genuine tripartite entanglement(GTE) for the W state. Moreover, the complementarity of GTN is verified by examining the nonlocality between the tripartite and the bipartite. Finally, we also find a useful strategy to protect the correlation of GTN and GTE under decoherence by utilizing the Zeno effect.

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arXiv2019

Comments on "Quantum theory cannot consistently describe the use of itself"

Recently, a delicately designed Gedankenexperiment was proposed to check the self-consistence of quantum theory in the description of the agents who are using this theory. It was demonstrated that the quantum theory is inconsistent. Here a critical improvement is presented, which can lead to a consistent explanation of the Gedankenexperiment by using quantum theory.

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arXiv2014

Sudden transitions of trace distance discord of dipole-dipole coupled two qubits

We investigate the exact dynamics of trace distance discord by considering two qubits under dephasing whose states belong to a class of $X$ states beyond Bell diagonal form. The necessary condition for the occurrence of freezing trace distance discord is found and compared with that of entropic discord. For an illustration, we consider two interacting qubits coupled to independent reservoirs and demonstrate these dynamical properties of trace distance discord. It is interesting to find that the freezing trace distance discord exists even for $X$ states without maximally mixed marginals and can be tuned by dipole-dipole coupling of two qubits. Moreover, we consider the initial extended Werner-like states and investigate the differences between trace distance discord and entanglement. The influences of initial state and the dipole-dipole coupling of the two qubits on the dynamics of nonclassical correlations are explored.

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arXiv2014

Negativity of quantumness and non-Markovianity in a qubit coupled to a thermal Ising spin bath system

We propose a scheme to characterize the non-Markovian dynamics and quantify the non-Markovianity via the non-classicality measured by the negativity of quantumness. By considering a qubit in contact with a critical Ising spin bath and introducing an ancilla, we show that revivals of negativity of quantumness indicate the non-Markovian dynamics. Furthermore, a normalized measure of non-Markovianity based on the negativity of quantumness is introduced and the influences of bath criticality, bath temperature and bath size on the non-Markovianity are discussed. It is shown that, at the critical point, the decay of non-Markovianity versus the size of spin bath is fastest and the non-Markovianity is exactly zero only in the thermodynamic limit. Besides, non-trivial behaviours of negativity of quantumness such as sudden change, double sudden changes and keeping constant are found for different relations between parameters of the initial state. Finally, how the non-classicality of the system is affected by a series of bang-bang pulses is also examined.

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arXiv2011

Sudden transition between classical and quantum decoherence in dissipative cavity QED and stationary quantum discord

We investigate the phenomenon of sudden transition between classical and quantum decoherence in the study of quantum discord for a dissipative cavity QED system, which consists of two noninteracting two-level atoms, each trapped in a dissipative cavity. It is found that the quantum discord between two atoms, which are prepared initially in the X-type quantum states, is not destroyed by the dissipation of the cavities for a finite time interval and the stationary quantum discord can arise in the interaction of atoms with cavities as the time approach to infinite. The transition time is sensitive to the initial state parameter of the two atoms and the mean photon number of the coherent field. Interestingly, the quantum discord between the two atoms is completely unaffected by the dissipation of the cavities if we choose the suitable value of the ratio, which depends on the decay rate of two cavities and the atom-field coupling constant.

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