Two-photon cooling of a nonlinear quantum oscillator

TL;DR

This paper investigates how a nonlinear quantum oscillator can be cooled below thermal background through its interaction with a qubit, considering environmental effects and nonlinearity, with potential applications across quantum systems.

Contribution

It introduces a general analytical formalism for two-photon cooling of nonlinear oscillators interacting with qubits, accounting for environmental dissipation and nonlinearity.

Findings

Effective cooling below thermal background achieved under certain conditions.

Distinct behaviors of photon coherence functions for even and odd photon states.

Formalism applicable to a wide range of quantum systems.

Abstract

The cooling effects of a nonlinear quantum oscillator via its interaction with an artificial atom (qubit) are investigated. The quantum dissipations through the environmental reservoir of the nonlinear oscillator are included, taking into account the nonlinearity of the qubit-oscillator interaction. For appropriate bath temperatures and the resonator's quality factors, we demonstrate effective cooling below the thermal background. As the photon coherence functions behave differently for even and odd photon number states, we describe a mechanism distinguishing those states. The analytical formalism developed is general and can be applied to a wide range of systems.