Measurement-protected quantum phases

By Shengqi Sang, Timothy H. Hsieh. Physical Review Research, 2020

175 citations recorded by the source corpus.

We introduce a class of hybrid quantum circuits, with random unitaries and projective measurements, which host long-range order in the area law entanglement phase of the steady state. Our primary example is circuits with unitaries respecting a global Ising symmetry and two competing types of measurements. The phase diagram has an area law phase with spin glass order, which undergoes a direct transition to a paramagnetic phase with volume law entanglement, as well as a critical regime. Using mutual information diagnostics, we find that such entanglement transitions preserving a global symmetry are in new universality classes. We analyze generalizations of such hybrid circuits to higher dimensions, which allow for coexistence of order and volume law entanglement, as well as topological order without any symmetry restrictions.

Subfields: Atomic and Molecular Physics, and Optics

View Paper: https://www.semanticscholar.org/paper/00533bc487d09e368b12bebf9a1e81082f946c43

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In Atomic and Molecular Physics, and Optics

1. Matthew Fisher
2. A. Nahum
3. V. Khemani
4. B. Skinner
5. J. Ruhman
6. S. Vijay
7. Sthitadhi Roy
8. Mario Motta

Citations in the corpus

• Measurement and Entanglement Phase Transitions in All-To-All Quantum Circuits, on Quantum Trees, and in Landau-Ginsburg Theory (2020, background): “One could also consider, say, measurement dynamics with an Ising symmetry [37, 40].”
• Random Quantum Circuits (2022, background): “Monitored many-body systems have been the subject of much recent progress (58, 59, 60, 61, 62, 54, 55, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 57, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84).”
• Measurement-induced entanglement phase transition on a superconducting quantum processor with mid-circuit readout (2022, background): “More generally, mid-circuit measurements can reduce the resources required to prepare novel entangled quantum states of matter [22, 28].”
• Measurement-induced quantum criticality under continuous monitoring (2020, unknown): “Such measurement-induced entanglement transitions have been studied in different setups of circuit models and from various physical aspects [16–30].”