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1.
The decoherence of two initially entangled qubits coupled with a
squeezed vacuum cavity separately is investigated exactly. The
results show that, first, in principle, the disentanglement time
decreases with the increase of squeeze parameter r, due to the
augmenting of average photon number of every mode in the squeezed
vacuum cavity. Second, there appear entanglement revivals after the
complete disentanglement for the case of even parity initial Bell
state, while there occur the entanglement decrease and the
entanglement revival before the complete disentanglement for the
case of odd parity initial Bell state. The results are quite
different from those for the case of qubits in a vacuum cavity. 相似文献
2.
《Physics letters. A》2020,384(16):126309
We study the relationship between the quantum speed limit (QSL) time of a three-qubit system, and the quantum phase transitions (QPTs) of a spin-chain environment with the three-spin interaction. We find that the three-spin interaction can effectively manipulate the critical value of the QSL time. It makes the QSL time mark more clearly the quantum phase transition of the one-dimensional spin-chain models, especially the XX model. The dynamical evolution of the QSL time presents a periodic behavior in quantum-critical environment, whereas the three-spin interaction and external magnetic field can destroy this periodicity. 相似文献
3.
J. L. Guo Y. J. Mi H. S. Song 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2012,66(1):24
We study the dynamics of quantum discord of two-qubit system in a quantum spin
environment at finite temperature in the thermodynamics limit. Special attention is paid
to the difference between the entanglement and quantum discord when considering the
influences of the environment temperature and the initial system states. We show that in
the same range of the physical parameters, when the system states behave no entanglement
or entanglement sudden death, the quantum discord keeps nonzero. So the quantum discord is
more robust than entanglement under this decoherence environment. Furthermore, we also
illustrate that we can tune the parameters related to the system and the environment to
suppress the decay of quantum discord. 相似文献
4.
X.-F. Cao H. Zheng 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(2):209-219
The disentanglement of a pair of identical qubits, sharing a dissipative environment, is investigated. We proposed a new non-Markovian
analytical method to study the model, which takes into account the counter-rotating term in the qubit-environment interaction.
It is shown that when the qubits sufficiently separate from each other, the model is equivalent to each subsystem interacts
independently with its local environment. The effects of the dissipative environment and the interqubit distance on the time
evolution of the concurrence for four bell states are examined in detail. And point out some new features appearing in the
case of the two qubits close together. 相似文献
5.
Josep Batle Mymona Abutalib Soliman Abdalla Ahmed Farouk 《The European Physical Journal B - Condensed Matter and Complex Systems》2016,89(11):247
Quantum correlations in a physical system are usually degraded whenever there is aninteraction with the environment. Here we consider the action of a XY spin-chain interactingwith a system of two qubits. Results are surprising for particular families of statessince their evolution does not destroy the presence of either entanglement or nonlocality,that is, those correlations persist for any possible configuration of theenvironment. In addition, we unveil the form of those states which, although being mixed,their entanglement implies nonlocality and vice versa. This finding constitutes anextension of the well-known Gisin Theorem for pure states of two qubits.The ensuing form will enable us to find the evolved entanglement and nonlocality in ananalytical fashion. 相似文献
6.
We investigate the entanglement dynamics and decoherence of a two-qubit system under a quantum spin environment at finite temperature in the thermodynamics limit. For the case under study, we find different initial states will result in different entanglement evolution, what deserves mentioning here is that the state |Ψ=cosα|01+sinα|10 is most robust than other states when π/2<α<π, since the entanglement remains unchanged or increased under the spin environment. In addition, we also find the anisotropy parameter Δ can suppress the destruction of decoherence induced by the environment, and the undesirable entanglement sudden death arising from the process of entanglement evolution can be efficiently controlled by the inhomogeneous magnetic field ζ. 相似文献
7.
Entanglement dynamics of two non-interacting atoms in a squeezed vacuum reservoir is studied. Several examples with different initial entangled states are investigated, and it is found that entangled atoms become disentangled faster in squeezed vacuum than in ordinary vacuum, and larger squeezing results in faster entanglement decay. The time evolution of the concurrence and the separability "distance" A can be used to explain this novel entanglement sudden death phenomenon. 相似文献
8.
The decoherence process characterized by Loschmidt echo (LE) in a two-level system dephasingly coupled to a fermion environment with phase transitions is studied in this Letter. The results show that the LE of the two-level system may act as a witness of the environment's phase transitions, which is similar to the relation between quantum phase transitions and the LE. 相似文献
9.
Avoiding the decay of entanglement for coupling two-qubit system interacting with a non-Markov environment 下载免费PDF全文
The entanglement evolution of the coupled qubits interacting with a non-Markov environment is investigated in terms of concurrence.The results show that the entanglement of the quantum systems depends not only on the initial state of the system but also on the coupling between the qubit and the environment.For the initial state (|00 ± |11) /21/2,the coupled qubits will always been in the maximum entangled state under an asymmetric coupling.For the initial state (|01 ± |10) /21/2,in contrast,the entangling degree of the coupled qubits is always equal to unity and does not depend on the evolving time under the symmetric coupling.We find that the stronger the interaction between the qubits is,the better the struggle against the entanglement sudden death is. 相似文献
10.
Correlation dynamics of a qubit–qutrit system in a spin-chain environment with Dzyaloshinsky–Moriya interaction 下载免费PDF全文
We study the dynamics of correlations for a hybrid qubit-qutrit system in an XY spin-chain environment with Dzyaloshinsky-Moriya interaction. Our discussion involves a comparative analysis of negativity, quantum discord, and measurement-induced disturbance. It is found that the quantum discord is optimal of the three quantum correlations to de- tect the critical point of quantum phase transition. Only when the qubit interacts with the environment, is the phenomenon of sudden transition between the classical correlation and the quantum discord observed. Moreover, the Dzyaloshinsky- Moriya interaction enhances the decay of quantum correlations. 相似文献
11.
The quantum entanglement,discord,and coherence dynamics of two spins in the model of a spin coupled to a spin bath through an intermediate spin are studied.The effects of the important physical parameters including the coupling strength of two spins,the interaction strength between the intermediate spin and the spin bath,the number of bath spins and the temperature of the system on quantum coherence and correlation dynamics are discussed in different cases.The frozen quantum discord can be observed whereas coherence does not when the initial state is the Bell-diagonal state.At finite temperature,we find that coherence is more robust than quantum discord,which is better than entanglement,in terms of resisting the influence of environment.Therefore,quantum coherence is more tenacious than quantum correlation as an important resource. 相似文献
12.
研究了由光子增减叠加操作作用于相干态而得量子态的非经典性及其在热环境中的退相干问题.通过解析导出了Mandel's Q参数、光子数分布、Wigner函数等,讨论其非经典性.研究表明一阶光子增减相干叠加相干态在相空间总是取负值,只要满足条件∣2z* +α-α*∣2<1.基于Wigner函数的演化积分公式,解析地推导出了在热环境中Wigner函数的简洁表达式.研究首次表明:如果κt<1/2ln[(2(η)+2)/(2(η)+1)]得以满足,一阶光子增减相干叠加相干态在相空间最小值点处Wigner函数分布总存在负部.此外,根据Wigner函数负部体积讨论了其非经典特性. 相似文献
13.
We present a simple equation to predict the sudden death time of two-qubit entanglement in a noisy environment. This result is valid for all two-qubit systems, no matter what kind of noise is considered. 相似文献
14.
L. C. Wang H. Y. Sun X. X. Yi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):723-728
Starting from the assumption that rod cells are sensitive to single photons, we propose a method to verify the existence of
a quantum superposition in the retina, observing the Rabi oscillations in the quantum interaction of a coherent laser light
with the rod cells. The computer simulation shows that the oscillations visibility is a robust parameter, so that it would
be possible to observe the fringes also in presence of strong decoherence. The feasibility of the experiment is ensured by
the new MEA (microelectrode array) technology, that allows to record the transretinal voltage change of a single retinal segment. 相似文献
15.
M. Ban 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(3):415-421
Decoherence of interacting two qubits placed
under the influence of a common environment
is studied by means of the quantum master equation,
where the two qubits interact with each other
via the XY-coupling and the two-qubit system
has the dephasing coupling with the environment.
It is shown that when the asymmetry of the
interaction between the two-qubit system and environment
is not small,
the qubit-qubit interaction significantly affects
the dephasing of the two-qubit system.
To examine such an interaction effect,
the decay of two-qubit entanglement is calculated.
It is found that the qubit-qubit interaction makes not only
the decay of entanglement small
but also the period of the oscillatory behaviour short. 相似文献
16.
Braun D 《Physical review letters》2006,96(23):230502
I show that the decoherence in a system of degenerate two-level atoms interacting with a bosonic heat bath is for any number of atoms governed by a generalized Hamming distance (called "decoherence metric") between the superposed quantum states, with a time-dependent metric tensor that is specific for the heat bath. The decoherence metric allows for the complete characterization of the decoherence of all possible superpositions of many-particle states, and can be applied to minimize the overall decoherence in a quantum memory. For qubits which are far apart, the decoherence is given by a function describing single-qubit decoherence times the standard Hamming distance. I apply the theory to cold atoms in an optical lattice interacting with blackbody radiation. 相似文献
17.
X. S. Ma H. S. Cong J. Y. Zhang A. M. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(2):285-292
The entanglement dynamics of three-qubit states under a general XY
spin-chain environment which can exhibit a quantum phase transition
is investigated by using negativity as entanglement measure. Our
results imply that the entanglement evolution depends not only on
the states of concern but also on the system-environment coupling,
the anisotropy parameter, the size of the environment, and the
strength of the external field applied to the environment. For the cases
under study, we find that the entanglement decay
is enhanced by quantum phase transition under weak coupling. The
conditions to identify quantum decoherence-free subspaces have been
discussed. 相似文献
18.
Nikola Buri? 《Physics letters. A》2010,374(40):4090-4098
Quantum state diffusion approach to open system dynamics is used to study decoherence and dynamics of the pointer observable of an angular momentum system in interaction with a macroscopic nonlinear and dissipative environment. It is shown that dispersion of the pointer observable in the mixed state of the open system is clearly larger if the environment is classically chaotic then in the case of the environment with regular dynamics. 相似文献
19.
20.
Kudasov YB 《Physical review letters》2006,96(2):027212
Because of a ferromagnetic in-chain coupling between Co3+ ions at trigonal sites, Co2O6 chains are considered as large rigid spin moments. The antiferromagnetic Ising model on the triangular lattice is applied to describe an interchain ordering. An evolution of metastable states in a sweeping magnetic field is investigated by the single-flip technique. At the first approximation two steps in the magnetization curve and a plateau at 1/3 of the saturation magnetization are found. Four steps in magnetization are determined in high-order approximations in agreement with experimental results. 相似文献