5 papers
Mixed-state Quantum Phases: Renormalization and Quantum Error Correction
Shengqi Sang, Yijian Zou, Timothy H. Hsieh
Open system quantum dynamics can generate a variety of long-range entangled mixed states, yet it has been unclear in what sense they constitute phases of matter. To establish that…
Circuit-based characterization of finite-temperature quantum phases and self-correcting quantum memory
Ruochen Ma, Vedika Khemani, Shengqi Sang
Quantum phases at zero temperature can be characterized as equivalence classes under local unitary transformations: two ground states within a gapped phase can be transformed into…
Mixed-state phases from local reversibility
Shengqi Sang, Leonardo A. Lessa, Roger S. K. Mong +3
We propose a refined definition of mixed-state phase equivalence based on locally reversible channel circuits. We show that such circuits preserve topological degeneracy and the lo…
Higher-form anomaly and long-range entanglement of mixed states
Leonardo A. Lessa, Shengqi Sang, Tsung-Cheng Lu +2
In open quantum systems, we directly relate anomalies of higher-form symmetries to the long-range entanglement of any mixed state with such symmetries. First, we define equivalence…
Approximate quantum error correcting codes from conformal field theory
Shengqi Sang, Timothy H. Hsieh, Yijian Zou
The low-energy subspace of a conformal field theory (CFT) can serve as a quantum error correcting code, with important consequences in holography and quantum gravity. We consider g…