Passive error correction with a qubit-oscillator system in noisy environment Passive error correction with a qubit-oscillator

• Published in: Journal of the Korean Physical Society Vol. 85; no. 11; pp. 890 - 897
• Main Authors: Zhu, Yanzhang, Hwang, Myung-Joong
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Physical Society 01.12.2024
• Subjects: Mathematical and Computational Physics; Molecules and Optics; Original Paper - Atoms; Particle and Nuclear Physics; Physics; Physics and Astronomy; Theoretical; Cat qubit; Open quantum system; Dissipative phase transition; Quantum error correction
• ISSN: 0374-4884; 1976-8524
• DOI: 10.1007/s40042-024-01216-2

In this paper, we study an open quantum system consisting of a qubit coupled to a harmonic oscillator subject to two-photon relaxation and demonstrate that such a system can be utilized to construct a cat qubit capable of passive error correction. To this end, we first show that the steady state of the qubit-oscillator system, described by the open quantum Rabi model with two-photon relaxation, undergoes a super-radiant phase transition that breaks the strong symmetry of the Lindblad master equation. In the strong symmetry-broken phase, we show that a cat qubit can be stabilized in the steady state by tuning the qubit-oscillator coupling strength and demonstrate that passive error correction can be realized against errors due to fluctuations in the system frequencies. Our study deepens the understanding of dissipative phases in a qubit-oscillator system with strong symmetry and paves the way to utilize them for passive error correction.