



01489nas a2200133   4500008004100000245007300041210006900114260001300183520106500196100001601261700001601277700002501293856003701318       2023                        eng d00aCandidate for a passively protected quantum memory in two dimensions0 aCandidate for a passively protected quantum memory in two dimens  c3/2/20233 a<p>An interesting problem in the field of quantum error correction involves finding a physical system that hosts a ``passively protected quantum memory,&#39;&#39; defined as an encoded qubit coupled to an environment that naturally wants to correct errors. To date, a quantum memory stable against finite-temperature effects is only known in four spatial dimensions or higher. Here, we take a different approach to realize a stable quantum memory by relying on a driven-dissipative environment. We propose a new model, the photonic-Ising model, which appears to passively correct against both bit-flip and phase-flip errors in two dimensions: A square lattice composed of photonic ``cat qubits&#39;&#39; coupled via dissipative terms which tend to fix errors locally. Inspired by the presence of two distinct Z2-symmetry-broken phases, our scheme relies on Ising-like dissipators to protect against bit flips and on a driven-dissipative photonic environment to protect against phase flips. We also discuss possible ways to realize the photonic-Ising model.</p>1 aLieu, Simon1 aLiu, Yu-Jie1 aGorshkov, Alexey, V.  uhttps://arxiv.org/abs/2205.09767