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Decoherence of the Radiation from an Accelerated Quantum Source
摘要： Decoherence is the process via which quantum superposition states are reduced to classical mixtures. Decoherence has been predicted for relativistically accelerated quantum systems; however, examples to date have involved restricting the detected field modes to particular regions of space-time. If the global state over all space-time is measured, then unitarity returns and the decoherence is removed. Here, we study a decoherence effect associated with accelerated systems that cannot be explained in this way. In particular, we study a uniformly accelerated source of a quantum field state—a single-mode squeezer. Even though the initial state of the field is vacuum (a pure state) and the interaction with the quantum source in the accelerated frame is unitary, we find that the final state detected by inertial observers appears to be decohered, i.e., in a mixed state. This unexpected result may indicate new directions in resolving inconsistencies between relativity and quantum theory. We extend this result to a two-mode state and find that entanglement is also decohered.
关键词： Unruh Effect,Quantum Field Theory,Accelerated Systems,Decoherence,Quantum Source
更新于2025-09-23 15:22:29
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Continuous-variable quantum teleportation with vacuum-entangled Rindler modes
摘要： We consider a continuous-variable quantum teleportation protocol between a uniformly accelerated sender in the right Rindler wedge, a conformal receiver restricted to the future light cone, and an inertial observer in the Minkowski vacuum. Using a nonperturbative quantum circuit model, the accelerated observer interacts unitarily with the Rindler modes of the field, thereby accessing entanglement of the vacuum as a resource. We find that a Rindler-displaced Minkowski vacuum state prepared and teleported by the accelerated observer appears mixed according to the inertial observer, despite a reduction of the quadrature variances below classical limits. This is a surprising result, since the same state transmitted directly from the accelerated observer appears as a pure coherent state to the inertial observer. The decoherence of the state is caused by an interplay of opposing effects as the acceleration increases: the reduction of vacuum noise in the output state for a stronger entanglement resource, constrained by the amplification of thermal noise due to the presence of Unruh radiation.
关键词： quantum circuit model,Rindler modes,Unruh effect,continuous-variable quantum teleportation,vacuum entanglement
更新于2025-09-23 15:19:57
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Collective transitions of two entangled atoms and the Fulling-Davies-Unruh effect
摘要： We calculate respectively, from the viewpoints of an instantaneously/locally inertial observer and a coaccelerated observer, the transition rates of the two-atom system in the symmetric/antisymmetric entangled state [jψ (cid:2)i]. The scalar fields to which the atoms are coupled are respectively assumed to be in the vacuum state and a thermal state in the instantaneously inertial frame and in the coaccelerated frame. We show that both the upward transition jψ (cid:2)i → jgAgBi and the downward transition jψ (cid:2)i → jeAeBi take place, where jgAgBi and jeAeBi represent two collective eigenstates of the two-atom system with both atoms in their ground state and excited state respectively, and the transition rates observed in the two frames are identical only if there exists a thermal bath at the Fulling-Davies-Unruh temperature in the coaccelerated frame. Though both the downward and upward transition rates are characterized by the Plankian factor, this factor does not show up in the average variation rate of energy of the two-atom system, as a result of the perfect cancellation of the terms in the transition rates in the instantaneously inertial frame multiplied by the Plankian factor which corresponds to the Unruh thermal bath, and the cancellation of the temperature-dependent terms in the transition rates observed in the coaccelerated frame. A comparison of the transition rates of a static two-atom system in interaction with the massless scalar field in a thermal state at an arbitrary temperature with those of a uniformly accelerated two-atom system in interaction with the vacuum massless scalar field shows that the equivalence between the thermal bath and the uniform acceleration, which is well known to be valid for the single atom case, no longer holds for the two-atom system in the symmetric/antisymmetric entangled state. The effect of atomic uniform acceleration in the transition rates of the two-atom system, and the roles of both the downward and the upward transitions in the disentanglement of the two-atom system are also discussed.
关键词： Fulling-Davies-Unruh effect,Collective transitions,transition rates,thermal bath,uniform acceleration,entangled atoms
更新于2025-09-23 15:19:57
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Quantum Coherence Behaviors for a Uniformly Accelerated Atom Immersed in Fluctuating Vacuum Electromagnetic Field with a Boundary
摘要： We investigate the dynamics of quantum coherence (QC) for a uniformly accelerated atom interacting with fluctuating electromagnetic field subject to a conductor boundary. We firstly derive the master equation that the atom evolution obeys. We find that without boundary, QC declines under the effect of Unruh thermal bath and vacuum fluctuation. However, with a boundary, the degradation, fluctuation, and preservation of QC are closely related to boundary effect, atomic polarization, and acceleration. Furthermore, in the presence of a boundary, QC can effectively be protected under the influence of the vacuum fluctuation and Unruh thermal effect when the atom is transversely polarizable and near this boundary, and the presence of boundary gives us more freedom of controlling the QC behaviors.
关键词： Dynamics,Unruh effect,Electromagnetic field,Quantum coherence
更新于2025-09-19 17:15:36