Anti-dynamical Casimir effect with an ensemble of qubits

Abstract We consider the interaction between a single cavity mode and N ≫ 1 identical qubits, assuming that any system parameter can be rapidly modulated in situ by external bias. It is shown that, for the qubits initially in the ground states, three photons can be coherently annihilated in the dispersive regime for harmonic modulation with frequency 3 ω 0 − Ω 0 , where ω 0 ( Ω 0 ) is the bare cavity (qubit) frequency. This phenomenon can be called “Anti-dynamical Casimir effect”, since a pair of excitations is destroyed without dissipation due to the external modulation. For the initial vacuum cavity state, three qubit excitations can also be annihilated for the modulation frequency 3 Ω 0 …