Dark Periods in Rabi Oscillations of Superconducting Phase Qubit Coupled to a Microscopic Two-Level System

TL;DR

This paper demonstrates macroscopic quantum jumps in a superconducting qubit coupled to a two-level system, revealing dark periods in Rabi oscillations that impact quantum information processing.

Contribution

The authors propose a scheme to observe quantum jumps in a superconducting qubit and develop an analytical model for dark period widths, supported by numerical simulations.

Findings

Identification of dark and bright periods in Rabi oscillations

Analytical model accurately describes dark period widths

Implications for quantum error correction in superconducting qubits

Abstract

We proposed a scheme to demonstrate macroscopic quantum jumps in a superconducting phase qubit coupled to a microscopic two-level system in the Josephson tunnel junction. Irradiated with suitable microwaves, the Rabi oscillations of the qubit exhibit signatures of quantum jumps: a random telegraph signal with long intervals of intense macroscopic quantum tunneling events (bright periods) interrupted by the complete absence of tunneling events (dark periods). An analytical model was developed to describe the width of the dark periods quantitatively. The numerical simulations indicate that our analytical model captured underlying physics of the system. Besides calibrating the quality of the microscopic two-level system, our results have significance in quantum information process since dark periods in Rabi oscillations are also responsible for errors in quantum computing with superconducting qubits.