Abstract Via using l 1-norm of quantum coherence and π–tangle, we investigate influences of amplitude-damping and depolarizing channels on quantum coherence and entanglement for W state of Dirac fields when two observers are in accelerating motion. We find that quantum entanglement vanishes for all values of acceleration if at least one qubit is under noisy channels. But quantum coherence does not vanish even at infinite acceleration if only one subsystem is under noisy channels. We also find that, unlike the depolarizing environment, the amplitude-damping environment can destroy symmetric properties of quantum entanglement with respect to two accelerated observers. These results will further enrich our understanding on the relation between quantum coherence and entanglement.
In this paper, we investigate the entanglement dynamics of a two-qubit entangled state coupled with its noisy environment, and plan to utilize weak measurement and quantum reversal measurement to study the entanglement dynamics under different decoherence channels in noninertial frames. Through the calculations and analyses, it is shown that the weak measurement can prevent entanglement from coupling to the amplitude damping channel, while the system is under the phase damping and flip channels. This protection protocol cannot prevent entanglement but will accelerate the death of entanglement. In addition, if the system is in the noninertial reference frame, then the effect of weak measurement will be weakened for the amplitude damping channel. Nevertheless, for other decoherence channels, the Unruh effect does not affect the quantum weak measurement, the only exception is that the maximum value of entanglement is reduced to √2/2 of the original value in the inertial frames.
We study the effects of decoherence on the entanglement generated by Unruh effect in accelerated frames by using various combinations of an amplitude damping channel, a phase damping channel and a depolarizing channel in the form of multilocal and collective environments. Using concurrence as entanglement quantifier, we show that the occurrence of entanglement sudden death (ESD) depends on different combinations of the channels. The ESD can be avoided under a particular configuration of the channels. We show that the channels can be used to distinguish between a moving and a stationary frame.
We study the effects of decoherence on the entanglement generated by the Unruh effect in noninertial frames by using phase flip, phase damping and depolarizing channels. It is shown that decoherence strongly influences the initial state entanglement. Entanglement sudden death can occur irrespective of the acceleration of the noninertial frame under the action of phase flip and phase damping channels. It is investigated that an early sudden death occurs for large acceleration under the depolarizing environment. Moreover, entanglement increases for a highly decohered phase flip channel.
Abstract The inherent association between real quantum systems and their surrounding environment invariably results in decoherence, leading to the loss of entanglement. This diminution in entanglement coincides with a decline in the fidelity of transmitted information using the entangled quantum resource. This study scrutinizes the impact of the squeezed generalized amplitude damping (SGAD) channel on quantum Fisher information (QFI) parameters. The SGAD channel model, a versatile framework, is also employed to simulate other dissipative channels, including amplitude damping (AD) and generalized amplitude damping (GAD). Kraus operators facilitate the modeling of noisy channels. The results reveal that, within the SGAD channel, the QFI remains impervious to the squeezing variables (r and
Φ Φ ). In the GAD channel,
FθGAD F θ GAD undergoes enhancement to a constant value with an upswing in temperature (T), while the
ϕ ϕ parameter in the GAD channel,
FϕGAD F ϕ GAD , akin to the SGAD channel, surges around T = 2 before complete loss ensues. Concerning the AD channel, the
θ θ component of the QFI initially experiences decoherence with an augmentation in the AD noise parameter (
λ λ ). Subsequently, it is restored to its initial value with a further escalation in
λ λ . Conversely, the
ϕ ϕ component of the QFI in the AD channel experiences decoherence with an elevation in the AD noise parameter (
λ λ ).
The fluctuation and relative fluctuation of entanglement entropy of a bipartite system for Dirac fields in noninertial frames are investigated. It is shown that the fluctuation and relative fluctuation of entanglement entropy are observer-dependent, which depend on their observed frames. It is found that both the fluctuation and relative fluctuation of entanglement entropy become more noticeable with the increasing of the subsystem's acceleration. We also find that the entanglement entropy always has fluctuation regardless of the initial state parameter and for any magnitude of the acceleration. We argue that the statistical mean for the measurement of entanglement entropy relates to the accelerated motion of the observer.