We study the dynamics of quantum coherence under Unruh thermal noise and seek under which condition the coherence can be frozen in a relativistic setting. We find that the frozen condition is either (i) the initial state is prepared as an incoherence state or (ii) the detectors have no interaction with the external field. That is to say, the decoherence of the detectors' quantum state is irreversible under the influence of thermal noise induced by Unruh radiation. It is shown that quantum coherence approaches zero only in the limit of an infinite acceleration, while quantum entanglement could reduce to zero for a finite acceleration. It is also demonstrated that the robustness of quantum coherence is better than entanglement under the influence of the atom-field interaction for an extremely large acceleration. Therefore, quantum coherence is more robust than entanglement in an accelerating system and the coherence-type quantum resources are more accessible for relativistic quantum information processing tasks.
We study the dynamics of quantum coherence under Unruh thermal noise and seek under which condition the coherence can be frozen in a relativistic setting. We find that the frozen condition is either (i) the initial state is prepared as an incoherence state or (ii) the detectors have no interaction with the external field. That is to say, the decoherence of the detectors' quantum state is irreversible under the influence of thermal noise induced by Unruh radiation. It is shown that quantum coherence approaches zero only in the limit of an infinite acceleration, while quantum entanglement could reduce to zero for a finite acceleration. It is also demonstrated that the robustness of quantum coherence is better than entanglement under the influence of the atom-field interaction for an extremely large acceleration. Therefore, quantum coherence is more robust than entanglement in an accelerating system and the coherence-type quantum resources are more accessible for relativistic quantum information processing tasks.
In this paper, we investigate the influence of the Unruh effect on the achievement of the nonlocal advantage of quantum coherence for a two-qubit system under a relativistic frame. The results show that with the increase of acceleration, it is difficult to realize the nonlocal advantage of quantum coherence and when the acceleration exceeds a certain value, nonlocal advantage of quantum coherence cannot be realized. In addition, we explore the dynamics of Bell nonlocality, steering, quantum coherence, entanglement and quantum discord (QD) under Unruh thermal noise. It is shown that nonlocal advantage of quantum coherence, Bell nonlocality, steering and entanglement experience “sudden death” for a finite acceleration, while quantum coherence and QD vanish only in the limit of an infinite acceleration. We also find that not all nonlocal states can achieve the nonlocal advantage of quantum coherence. It is also demonstrated that the robustness of Bell nonlocality is better than nonlocal advantage of quantum coherence under the influence of the Unruh noise.
Abstract Recent studies have increasingly focused on the effect of relativistic motion on quantum coherence. Prior research predominantly examined the influence of relative motion on basis-dependent quantum coherence, underscoring its susceptibility to decoherence under accelerated conditions. Yet, the effect of relativistic motion on basis-independent quantum coherence, which is critical for understanding the intrinsic quantum features of a system, remains an interesting open question. This paper addresses this question by examining how total, collective, and localized coherence are affected by acceleration and coupling strength. Our analysis reveals that both total and collective coherence significantly decrease with increasing acceleration and coupling strength, ultimately vanishing at high levels of acceleration. This underscores the profound impact of Unruh thermal noise. Conversely, localized coherence exhibits relative stability, decreasing to zero only under the extreme condition of infinite acceleration. Moreover, we demonstrate that collective, localized, and basis-independent coherence collectively satisfy the triangle inequality. These findings are crucial for enhancing our understanding of quantum information dynamics in environments subjected to high acceleration and offer valuable insights on the behavior of quantum coherence under relativistic conditions.
Abstract Quantum coherence of the tripartite W state and Greenberger–Horne–Zeilinger (GHZ) state under the Unruh effect are explored based on the model of a two‐level detector qubit coupled to a massless scalar field. The results reveal that Unruh thermal noise really destroys tripartite quantum resources. It is worth mentioning that the quantum coherence of the GHZ state reaches zero in the infinite acceleration limit, but that of the W‐state always remains nonzero. Coherence of the GHZ state displays a sudden death as the coupling parameter grows, while coherence freezing can be witnessed for the W state. It can be concluded that the W state is more robust than the GHZ state against Unruh radiation. Moreover, the related investigation can be expanded to N‐qubit quantum systems and the corresponding analytical solution is obtained. It indicates that the larger number W‐type entangled qubit can be as a better quantum resource for quantum information tasks under the Unruh effect.
It is well known that the quantum fluctuation of entanglement (QFE) between Unruh–De Witt detector (modeled by a two-level atom) is always investigated in a relativistic setting. However, both of the Unruh radiation and quantum fluctuation effects play an important role in precise measurements of quantum entanglement. In this paper, we have quantitatively analyzed how the relativistic motion affects the QFE for two entangled Unruh–De Witt detectors, one of which is accelerated and interacting with the neighbor external scalar field. Our results show that the QFE, which initially increases by the Unruh thermal noise, will suddenly decay when the acceleration reaches to a considerably large value. Therefore, the relativistic effect will lead to non-negligible QFE effect. We also find that the initial QFE (without acceleration effect) reaches its minimum value at the maximally entangled state and the separable state. More importantly, our analysis demonstrates that although the QFE has a huge decay when the acceleration is greater than ∼0.96, the ratio of ΔE/C is still very large, due to the simultaneous decay of concurrence to a very low value. Finally, enlightened by the well-known equivalence principle, we discuss the possibility of applying the above findings to the dynamics of QFE under the influence of gravitation field.
We study a uniformly accelerated detector coupled to a massless scalar field for a finite time interval. By considering the detector initially prepared in a superposition state, qubit state, we find that the acceleration induces decoherence on the qubit. Our results suggest the dependence of loss of coherence on the polar angle of qubit state on a Bloch sphere and the time interaction. The adjust those parameters can significantly improve the conditions to estimate the degree of decoherence induced by Unruh radiation.
We investigate the relativistic dynamics of quantum entanglement in a four-qubit cluster (CL4) state using a fully operational Unruh-DeWitt detector framework. Contrary to the widely held expectation that the Unruh effect inevitably degrades initially maximal entanglement, we demonstrate that the 1−3 bipartite entanglement of the CL4 state remains strictly maximal for all accelerations, including the infinite-acceleration limit. This result uncovers a previously unexplored phenomenon, namely the ``complete freezing of initially maximal entanglement" under relativistic motion. To the best of our knowledge, this is the first identification and systematic characterization of such a phenomenon within a relativistic framework. These findings overturn the conventional view that acceleration universally diminishes maximal entanglement and establish the CL4 state as a promising resource for quantum information processing in non-inertial or curved-spacetime settings.