TY - JOUR T1 - Symmetry breaking and error correction in open quantum systems JF - Phys. Rev. Lett. Y1 - 2020 A1 - Simon Lieu A1 - Ron Belyansky A1 - Jeremy T. Young A1 - Rex Lundgren A1 - Victor V. Albert A1 - Alexey V. Gorshkov AB -

Symmetry-breaking transitions are a well-understood phenomenon of closed quantum systems in quantum optics, condensed matter, and high energy physics. However, symmetry breaking in open systems is less thoroughly understood, in part due to the richer steady-state and symmetry structure that such systems possess. For the prototypical open system---a Lindbladian---a unitary symmetry can be imposed in a "weak" or a "strong" way. We characterize the possible Zn symmetry breaking transitions for both cases. In the case of Z2, a weak-symmetry-broken phase guarantees at most a classical bit steady-state structure, while a strong-symmetry-broken phase admits a partially-protected steady-state qubit. Viewing photonic cat qubits through the lens of strong-symmetry breaking, we show how to dynamically recover the logical information after any gap-preserving strong-symmetric error; such recovery becomes perfect exponentially quickly in the number of photons. Our study forges a connection between driven-dissipative phase transitions and error correctio

VL - 125 U4 - 240405 UR - https://arxiv.org/abs/2008.02816 U5 - https://doi.org/10.1103/PhysRevLett.125.240405 ER -