发表机构
Joint Quantum Institute, NIST/University of Maryland; Joint Center for Quantum Information and Computer Science, NIST/University of Maryland; Department of Physics and Astronomy, Center for Quantum Research and Technology, University of Oklahoma（联合量子研究所，美国国家标准与技术研究院/马里兰大学; 联合量子信息与计算机科学中心，美国国家标准与技术研究院/马里兰大学; 俄克拉荷马大学物理与天文学系、量子研究与技术中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文通过引入幂律长程量子信道，在一维系统中诱导出强到弱自发对称破缺相变，构建了包含平凡、混合SPT和SW-SSB相的相图，并建立了逻辑信息丢失与SW-SSB的联系，且所提混合态可调至高纯度以利于实验实现。
AI 中文摘要
开放量子系统可以表现出固有的混合量子序，例如强到弱自发对称破缺（SW-SSB），这种序在纯态中没有对应物。通常预期，在一维空间中，有限深度的局域量子信道无法诱导向SW-SSB的相变。我们通过引入一种长程量子信道来规避这一障碍，该信道对位点对实施两体退相干，其概率随位点间距按幂律衰减。将此信道应用于一个插值于平凡相和对称保护拓扑（SPT）相之间的单参数矩阵乘积态族，我们构建了一个相图，该相图相对于Rényi-2诊断，拥有平凡相、混合SPT相和SW-SSB相。值得注意的是，混合SPT相不同于先前研究的退相干SPT相：它拥有两个逻辑量子比特，并表现出非零的Rényi-2弦序，尽管常规弦序消失。通过一系列映射到经典统计力学模型，我们建立了该模型中逻辑信息丢失与SW-SSB出现之间的直接联系。最后，我们考虑了所研究现象的实验实现的可行性。我们强调，我们的混合态族可以调节到高纯度区域，大幅减少测量开销，并使其在近期量子硬件上的实验实现和检测成为可能。
英文摘要
Open quantum systems can exhibit inherently mixed quantum orders, such as strong-to-weak spontaneous symmetry breaking (SW-SSB), which have no analogue in pure states. It is generally expected that a finite-depth local quantum channel cannot induce a phase transition to SW-SSB in one spatial dimension. We circumvent this obstruction by introducing a long-range quantum channel, which implements two-body dephasing on pairs of sites with probability falling off according to a power-law in the site separation. Applying this channel to a one-parameter family of matrix product states interpolating between trivial and symmetry-protected topological (SPT) phases, we construct a phase diagram that hosts trivial, mixed SPT, and SW-SSB phases with respect to Rényi-2 diagnostics. Notably, the mixed SPT phase is distinct from previously studied decohered SPT phases: it hosts two logical qubits and exhibits nonvanishing Rényi-2 string order, despite vanishing conventional string order. Through a series of mappings to a classical statistical mechanics model, we establish a direct connection between the loss of logical information and the onset of SW-SSB in this model. Finally, we consider the feasibility of experimental realization of the phenomena we have studied. We emphasize that our family of mixed states can be tuned to regimes of high purity, substantially reducing measurement overhead and enabling their experimental realization and detection on near-term quantum hardware.
Comments20+18 pages, 5+4 figures
