Population Inversion Induced by Landau-Zener Transition in a Strongly Driven rf-SQUID

TL;DR

This paper reports microwave-induced population inversion in a strongly driven rf-SQUID flux qubit, achieved through Landau-Zener transitions, enabling new methods for qubit initialization and potential applications in micromaser technology.

Contribution

It demonstrates microwave resonance phenomena and population inversion in a driven rf-SQUID flux qubit, utilizing Landau-Zener transitions for qubit control.

Findings

Observation of microwave resonances in a driven rf-SQUID

Generation of population inversion at low flux bias

Modulation of resonance peaks by microwave power

Abstract

Microwave resonances between discrete macroscopically distinct quantum states with single photon and multiphoton absorption are observed in a strongly driven radio frequency superconducting quantum interference device flux qubit. The amplitude of the resonant peaks and dips are modulated by the power of the applied microwave irradiation and a population inversion is generated at low flux bias. These results, which can be addressed with Landau-Zener transition, are useful to develop an alternative means to initialize and manipulate the flux qubit, as well as to do a controllable population inversion used in a micromaser.