Decoherence and Landauer’s principle in qubit-cavity quantum-field-theory interaction

Abstract

We consider quantum decoherence and Landauer’s principle in qubit-cavity quantum field theory (QFT) interaction, treating the qubit as the system and cavity QFT as the environment. In particular, we investigate the changes that occur in the system with a pure initial state and environment during the decoherence process, with or without energy dissipation, and compare the results with the case in which the initial state of the system is a mixed state and thus decoherence is absent. When we choose an interaction Hamiltonian such that the energy and coherence of the system change simultaneously, the population change of the system and the energy change are the same when the initial state is mixed. However, the decoherence terms increase the von Neumann entropy of the system. In this case the energy change and decoherence of the system are not independent physical processes. The decoherence process maintains unitarity. On the other hand, if the interaction Hamiltonian does not change the energy of the system, there is only the decoherence effect. The environment will be a distribution in the basis of the displaced number state and always increases the energy. Landauer’s principle is satisfied in both cases.

Decoherence and thermalization of Unruh-DeWitt detector in arbitrary dimensions

“…They directly relate the nature of the detector and the quantum field theory, which may provide JHEP03(2023)179 clues for future experiments, especially in the future spacebased experiments Recently it was found that the decoherence rate can be used to measure the Unruh effect [39]. We can also study the exchange of energy and information during the interaction between the detector and quantum field theory [40][41][42], which may help us to understand the feedback and back-reaction obtained from the measurements, as well as the connection between gravity and quantum theory. In [41] we also investigated the decoherence of the qubit coupled to a thermal quantum field theory in a cavity, and the results are also consistent with our Theorem 1.…”

“…We can also study the exchange of energy and information during the interaction between the detector and quantum field theory [40][41][42], which may help us to understand the feedback and back-reaction obtained from the measurements, as well as the connection between gravity and quantum theory. In [41] we also investigated the decoherence of the qubit coupled to a thermal quantum field theory in a cavity, and the results are also consistent with our Theorem 1. Of course, when we consider the thermal state instead of the Unruh effect, the Fermi-Dirac distribution does not appear in odd dimensions.…”

“…When the time tends to infinity, the former reduces to the latter. In the present work we study the decoherence rate and thermalization rate, where the integration range is always infinite, while in [41] we investigated a situation similar to the [43]. Interested readers can find a more detailed discussion in these papers.…”

Decoherence and thermalization of Unruh-DeWitt detector in arbitrary dimensions

“…Recently it was found that the decoherence rate can be used to measure the Unruh effect [38]. We can also study the exchange of energy and information during the interaction between the detector and quantum field theory [39][40][41], which may help us to understand the feedback and back-reaction obtained from the measurements, as well as the connection between gravity and quantum theory. In [40] we also investigated the decoherence of the qubit coupled to a thermal quantum field theory in a cavity, and the results are also consistent with our Theorem 1.…”

“…We can also study the exchange of energy and information during the interaction between the detector and quantum field theory [39][40][41], which may help us to understand the feedback and back-reaction obtained from the measurements, as well as the connection between gravity and quantum theory. In [40] we also investigated the decoherence of the qubit coupled to a thermal quantum field theory in a cavity, and the results are also consistent with our Theorem 1. Of course, when we consider the thermal state instead of the Unruh effect, the Fermi-Dirac distribution does not appear in odd dimensions.…”