Quasienergies and dynamics of superconducting qubit in time-modulated field

TL;DR

This paper investigates the complex dynamics of superconducting qubits under bichromatic, time-modulated fields, revealing quantum effects beyond monochromatic excitation and identifying regimes of regular population oscillations.

Contribution

It introduces a detailed analysis of quasienergies and Floquet states for superconducting qubits driven by bichromatic fields, extending understanding beyond traditional monochromatic models.

Findings

Identification of quasienergy zeros and their dependence on field amplitude

Demonstration of aperiodic and periodic population oscillations

Analysis of Floquet states in various resonant regimes

Abstract

We analyze the dynamics of a superconducting qubit and the phenomenon of multiorder Rabi oscillations in the presence of a time-modulated external field. Such a field is also presented as a bichromatic field consisting of two spectral components, which are symmetrically detuned from the qubit resonance frequency. This approach leads to obtaining qualitative quantum effects beyond those for the case of monochromatic excitation of qubits. We calculate Floquet states and quasienergies of the composite system "superconducting qubit plus time-modulated field" for various resonant regimes. We analyze the dependence of quasienergies from the amplitude of an external field, demonstrating the zeros of difference between quasienergies. We show that, as a rule, populations of qubit states exhibit aperiodic oscillations, but we demonstrate the specific important regimes in which dynamics of populations becomes periodically regular.