Probe spectroscopy of quasienergy states

TL;DR

This paper investigates the quasienergy states of a driven qubit using Floquet theory, combining analytical and numerical methods, and compares the results with recent experiments to advance understanding of probe spectroscopy in quantum systems.

Contribution

It introduces a Floquet-based approach to analyze probe spectroscopy of quasienergy states in driven qubits, including realistic parameters and experimental comparisons.

Findings

Floquet method effectively describes quasienergy states in driven qubits.

Analytical and numerical results agree with experimental data.

Longitudinal drive components significantly influence quasienergy spectra.

Abstract

The present qubit technology, in particular in Josephson qubits, allows an unprecedented control of discrete energy levels. This motivates a new study of the old pump-probe problem, where a discrete quantum system is driven by a strong drive and simultaneously probed by a weaker one. The strong drive is included by the Floquet method and the resulting quasienergy states are then studied with the probe. We study a qubit where the harmonic drive has a significant longitudinal component relative to the static equilibrium state of the qubit. Both analytical and numerical methods are used to solve the problem. We present calculations with realistic parameters and compare the results with recent experimental results. A short introduction to the Floquet method and the probe absorption is given.