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MP: Fachverband Theoretische und Mathematische Grundlagen der Physik

MP 2: Quantum Information and Gravity

MP 2.1: Talk

Monday, March 18, 2024, 10:00–10:20, HL 102

Overlapping qubits from non-isometric maps and de Sitter tensor networks — ChunJun Cao¹, Wissam Chemissany², •Alexander Jahn³, and Zoltan Zimboras⁴ — ¹Virginia Tech, Blacksburg, VA, USA — ²University of Pennsylvania, Philadelphia, PA, USA — ³Freie Universität Berlin, Berlin, Germany — ⁴Wigner Research Centre, Budapest, Hungary

We construct approximately local observables, or “overlapping qubits”, using non-isometric maps and show that processes in local effective theories can be spoofed with a quantum system with fewer degrees of freedom, similar to our expectation in holography. Furthermore, the spoofed system naturally deviates from an actual local theory in ways that can be identified with features in quantum gravity. For a concrete example, we construct two MERA toy models of de Sitter space-time and explain how the exponential expansion in global de Sitter can be spoofed with many fewer quantum degrees of freedom and that local physics may be approximately preserved for an exceedingly long time before breaking down. We highlight how approximate overlapping qubits are conceptually connected to Hilbert space dimension verification, degree-of-freedom counting in black holes and holography, and approximate locality in quantum gravity.

Keywords: De Sitter spacetime; Quantum gravity; Tensor networks