Emission spectrum of a qubit under its deep strong driving in the high-frequency dispersive regime

TL;DR

This paper investigates the emission spectrum of a strongly driven qubit in the high-frequency dispersive regime, deriving analytical expressions and revealing how the spectrum's features depend on driving strength and decoherence rates.

Contribution

It provides closed-form formulas for the emission spectrum of a qubit under deep strong driving in a high-frequency dispersive regime, highlighting the dependence on decoherence.

Findings

Spectrum contains narrow delta-like lines and Lorenzian peaks.

Line widths oscillate with driving strength.

Features are governed by qubit dephasing and relaxation rates.

Abstract

We study the emission spectrum of a qubit under deep strong driving in the high-frequency dispersive regime when the driving frequency and strength exceed significantly the qubit transition frequency. Closed-form expressions for the steady-state first-order field correlation function and the multiphoton emission spectrum are obtained. The spectrum comprises a series of narrow delta-like lines that stem from coherent processes and Lorenzian peaks that result from the incoherent scattering of photons. The oscillating dependence of the widths of the emission lines on the driving strength is predicted. We show how the features of this dependence are governed by the qubit dephasing and relaxation rates.