Quantum Many-Body Scars in Dual-Unitary Circuits

TL;DR

This paper introduces a method to embed quantum many-body scars into dual-unitary circuits, creating systems that defy typical thermalization despite being chaotic, with potential for experimental realization.

Contribution

The authors develop a novel approach to construct dual-unitary circuits with embedded scars, challenging the assumption that such circuits always thermalize.

Findings

Scar states exhibit slower entanglement growth compared to nonscar states.

Embedded scars prevent thermalization in maximally chaotic dual-unitary circuits.

Numerical simulations confirm the analytic predictions.

Abstract

Dual-unitary circuits are a class of quantum systems for which exact calculations of various quantities are possible, even for circuits that are nonintegrable. The array of known exact results paints a compelling picture of dual-unitary circuits as rapidly thermalizing systems. However, in this Letter, we present a method to construct dual-unitary circuits for which some simple initial states fail to thermalize, despite the circuits being "maximally chaotic," ergodic and mixing. This is achieved by embedding quantum many-body scars in a circuit of arbitrary size and local Hilbert space dimension. We support our analytic results with numerical simulations showing the stark contrast in the rate of entanglement growth from an initial scar state compared to nonscar initial states. Our results are well suited to an experimental test, due to the compatibility of the circuit layout with the native structure of current digital quantum simulators.