Dynamics of mesoscopic qubit ensemble coupled to cavity: role of collective dark states

TL;DR

This paper investigates how collective dark states influence the dynamics of a disordered mesoscopic qubit ensemble coupled to a cavity, revealing quantum interference effects and potential applications in quantum technologies.

Contribution

It demonstrates the persistence of quantum interference and the role of dark states in mesoscopic qubit-cavity systems, bridging few-qubit and many-qubit regimes with exact solutions.

Findings

Quantum interference effects survive in mesoscopic regimes.

Dark states slow down relaxation of entangled states.

Photon excitations are absorbed and released quasiperiodically.

Abstract

We consider dynamics of a disordered ensemble of qubits interacting with single mode photon field, which is described by exactly solvable inhomogeneous Dicke model. In particular, we concentrate on the crossover from few-qubit systems to the system of many qubits and analyze how collective behavior of coupled qubits-cavity system emerges despite of the broadening. We show that quantum interference effects survive in the mesoscopic regime -- dynamics of an entangled Bell state encoded into the qubit subsystem remains highly sensitive to the symmetry of the total wave function. Moreover, relaxation of these states is slowed down due to the formation of collective dark states weakly coupled to light. Dark states also significantly influence dynamics of excitations of photon subsystem by absorbing them into the qubit subsystem and releasing quasiperiodically in time. We argue that predicted phenomena can be useful in quantum technologies based on superconducting qubits. For instance, they provide tools to deeply probe both collective and quantum properties of such artificial macroscopic systems.