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TT: Fachverband Tiefe Temperaturen

TT 18: Superconductivity: Poster

TT 18.37: Poster

Monday, March 18, 2024, 15:00–18:00, Poster C

Stability of Nishimori cat states and non-equilibrium entanglement transitions — •Malte Pütz, Guo-Yi Zhu, and Simon Trebst — Institute for Theoretical Physics, University of Cologne, Zülpicher Straße 77, 50937 Cologne, Germany

Shallow quantum circuits that combine unitary gates with non-unitary measurements, so-called monitored quantum circuits, can create long-range entanglement (LRE) in O(1) steps - substantially faster than local unitary circuits, where entanglement creation is bounded by an information lightcone (Lieb-Robinson bounds). An open question is the stability of such engineered LRE when the circuit itself exhibits imperfections (such as incomplete gate operations or shifted measurements). Here we build on recent work from our group discuss the preparation of 'Nishimori cat' states, which exhibit a robustness to such imperfections, and explore extensions to imperfect lattice geometries (interpolating between one and two spatial dimensions) and Gaussian coherent noise. We characterize the post-measurement quantum wavefunction by various entanglement quantities and show exotic quantum criticality induced by the inclusion of such circuit imperfections. Our work employs state-of-the-art numerical simulation techniques, including hybrid Monte Carlo / tensor network calculations.

Keywords: circuits; non-equilibrium; entanglement; Nishimori; tensor network