Regular Article

Probabilistic motional averaging^★

¹ B. Verkin Institute for Low Temperature Physics and Engineering, Kharkov, Ukraine
² Leibniz Institute of Photonic Technology, Jena, Germany
³ ARC Centre of Excellence for Engineered Quantum Systems, St. Lucia, Queensland 4072, Australia
⁴ Okinawa Institute of Science and Technology Graduate University, Onna, 904-0495 Okinawa, Japan
⁵ School of Mathematics and Physics, University of Queensland, St Lucia, Queensland 4072, Australia
⁶ Novosibirsk State Technical University, Novosibirsk, Russia
⁷ V. N. Karazin Kharkov National University, Kharkov, Ukraine

^a e-mail: karpov@ilt.kharkov.ua

Received: 22 October 2019
Received in final form: 3 December 2019
Published online: 11 March 2020

Abstract

In a continuous measurement scheme a spin-1/2 particle can be measured and simultaneously driven by an external resonant signal. When the driving is weak, it does not prevent the particle wave-function from collapsing and a detector randomly outputs two responses corresponding to the states of the particle. In contrast, when driving is strong, the detector returns a single response corresponding to the mean of the two single-state responses. This situation is similar to a motional averaging, observed in nuclear magnetic resonance spectroscopy. We study such quantum system, being periodically driven and probed, which consists of a qubit coupled to a quantum resonator. It is demonstrated that the transmission through the resonator is defined by the interplay between driving strength, qubit dissipation, and resonator linewidth. We demonstrate that our experimental results are in good agreement with numerical and analytical calculations.