Effective Landau-Zener transitions in circuit dynamical Casimir effect with time-varying modulation frequency

TL;DR

This paper demonstrates how controlled Landau-Zener transitions in a circuit QED setup can enable efficient photon generation from vacuum, even with short frequency sweeps and without precise resonance tuning.

Contribution

It introduces a method to achieve effective Landau-Zener transitions in circuit QED with time-varying modulation frequency, facilitating photon creation without exact frequency knowledge.

Findings

Almost complete state transitions are possible with short frequency sweeps.

Photon generation can be achieved within microseconds using current technology.

The scheme is robust against the lack of precise resonance frequency knowledge.

Abstract

We consider the dissipative single-qubit circuit QED architecture in which the atomic transition frequency undergoes a weak external time-modulation. For sinusoidal modulation with linearly varying frequency we derive effective Hamiltonians that resemble the Landau-Zener problem of finite duration associated to a two- or multi-level systems. The corresponding off-diagonal coupling coefficients originate either from the rotating or the counter-rotating terms in the Rabi Hamiltonian, depending on the values of the modulation frequency. It is demonstrated that in the dissipation less case one can accomplish almost complete transitions between the eigenstates of the bare Rabi Hamiltonian even for relatively short duration of the frequency sweep. To assess the experimental feasibility of our scheme we solved numerically the phenomenological and the microscopic quantum master equations in the Markovian regime at zero temperature. Both models exhibit qualitatively similar behavior and indicate that photon generation from vacuum via effective Landau-Zener transitions could be implemented with the current technology on the timescales of a few microseconds. Moreover, unlike the harmonic dynamical Casimir effect implementations, our proposal does not require the precise knowledge of the resonant modulation frequency to accomplish meaningful photon generation.