Photon creation from vacuum and interactions engineering in nonstationary circuit QED

TL;DR

This paper theoretically investigates how nonstationary circuit QED systems with periodically modulated parameters can generate photons from vacuum, simulating the dynamical Casimir effect and producing entangled photon states.

Contribution

It introduces a theoretical framework for photon creation in nonstationary circuit QED via periodic modulation, highlighting the effective Hamiltonians and regimes where the dynamical Casimir effect occurs.

Findings

Photon creation from vacuum is possible in nonstationary circuit QED.

Resonant modulation leads to dynamical Casimir and Jaynes-Cummings effects.

Entangled photon states can be generated from vacuum.

Abstract

We study theoretically the nonstationary circuit QED system in which the artificial atom transition frequency, or the atom-cavity coupling, have a small periodic time modulation, prescribed externally. The system formed by the atom coupled to a single cavity mode is described by the Rabi Hamiltonian. We show that, in the dispersive regime, when the modulation periodicity is tuned to the `resonances', the system dynamics presents the dynamical Casimir effect, resonant Jaynes-Cummings or resonant Anti-Jaynes-Cummings behaviors, and it can be described by the corresponding effective Hamiltonians. In the resonant atom-cavity regime and under the resonant modulation, the dynamics is similar to the one occurring for a stationary two-level atom in a vibrating cavity, and an entangled state with two photons can be created from vacuum. Moreover, we consider the situation in which the atom-cavity coupling, the atomic frequency, or both have a small nonperiodic time modulation, and show that photons can be created from vacuum in the dispersive regime. Therefore, an analog of the dynamical Casimir effect can be simulated in circuit QED, and several photons, as well as entangled states, can be generated from vacuum due to the anti-rotating term in the Rabi Hamiltonian.