214 citations · 524 across the 16 of their papers we have counts for
11 papers · 1 filter
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…
Information dynamics in decohered quantum memory with repeated syndrome measurements: a dual approach
Jacob Hauser, Yimu Bao, Shengqi Sang +3
Measurements can detect errors in a decohered quantum memory allowing active error correction to increase the memory time. Previous understanding of this mechanism has focused on e…
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…
Stability of mixed-state quantum phases via finite Markov length
Shengqi Sang, Timothy H. Hsieh
For quantum phases of Hamiltonian ground states, the energy gap plays a central role in ensuring the stability of the phase as long as the gap remains finite. We propose Markov len…
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…
Random insights into the complexity of two-dimensional tensor network calculations
Sofia Gonzalez-Garcia, Shengqi Sang, Timothy H. Hsieh +4
Projected entangled pair states (PEPS) offer memory-efficient representations of some quantum many-body states that obey an entanglement area law, and are the basis for classical s…
Channeling quantum criticality
Yijian Zou, Shengqi Sang, Timothy H. Hsieh
We analyze the effect of decoherence, modelled by local quantum channels, on quantum critical states and we find universal properties of the resulting mixed state's entanglement, b…
Probing sign structure using measurement-induced entanglement
Cheng-Ju Lin, Weicheng Ye, Yijian Zou +2
The sign structure of quantum states is closely connected to quantum phases of matter, yet detecting such fine-grained properties of amplitudes is subtle. Here we employ as a diagn…
Entanglement Dynamics of Noisy Random Circuits
Zhi Li, Shengqi Sang, Timothy H. Hsieh
The process by which open quantum systems thermalize with an environment is both of fundamental interest and relevant to noisy quantum devices. As a minimal model of this process,…