论文标题
开放量子系统中的对称破坏和误差校正
Symmetry breaking and error correction in open quantum systems
论文作者
论文摘要
破坏对称性的过渡是量子光学,冷凝物和高能量物理学中封闭量子系统的一种充分理解的现象。但是,在开放系统中破坏对称性的部分是由于这种系统所具有的较丰富的稳态和对称结构。对于原型开放系统---林德布拉德式---可以以“弱”或“强”方式强加的单一对称性。我们表征了两种情况下可能的$ \ mathbb {z} _n $对称破坏过渡。在$ \ mathbb {z} _2 $的情况下,一个弱对称性的相位最多可以保证经典的位稳态结构,而强度对称性的相位相位则是部分受到保护的稳态量子量子。通过强度对称性破裂的镜头查看光子猫量子矩,我们展示了如何在任何具有GAP的强度对称误差后动态恢复逻辑信息;这种恢复在光子的数量中迅速呈指数指数级别。我们的研究建立了驱动驱动相变和误差校正之间的联系。
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 $\mathbb{Z}_n$ symmetry breaking transitions for both cases. In the case of $\mathbb{Z}_2$, 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 correction.