Cavity cooling to the ground state of an ensemble quantum system

TL;DR

This paper introduces a collective cavity cooling method combined with dissipative perturbation theory to efficiently initialize large ensemble quantum systems in their ground state, even with local dephasing noise.

Contribution

It develops a dissipative perturbation approach using average Hamiltonian theory and SU(4) algebra to analytically solve the dynamics of ensemble qubits under cavity cooling.

Findings

Effective dissipator causes local T1 relaxation to ground state

Method enables parallel high-purity state initialization

Analytical solution applicable to large ensembles

Abstract

We describe a method for initializing an ensemble of qubits in a pure ground state by applying collective cavity cooling techniques in the presence of local dephasing noise on each qubit. To solve the dynamics of the ensemble system we introduce a method for dissipative perturbation theory that applies average Hamiltonian theory in an imaginary-time dissipative interaction frame to find an average effective dissipator for the system dynamics. We use SU(4) algebra generators to analytically solve the first order perturbation for an arbitrary number of qubits in the ensemble. We find that to first order the effective dissipator describes local $T_1$ thermal relaxation to the ground state of each qubit in the ensemble at a rate equal to the collective cavity cooling dissipation rate. The proposed technique should permit the parallel initialization of high purity states in large ensemble quantum systems based on solid-state spins.