Gauged cooling of topological excitations and emergent fermions on quantum simulators

Abstract

Simulated cooling is a robust method for preparing low-energy states of many-body Hamiltonians on near-term quantum simulators. In such schemes, a subset of the simulator's spins (or qubits) are treated as a ``bath,'' which extracts energy and entropy from the system of interest. However, such protocols are inefficient when applied to systems whose excitations are highly non-local in terms of the microscopic degrees of freedom, such as topological phases of matter; such excitations are difficult to extract by a local coupling to a bath. We explore a route to overcome this obstacle by encoding of the microscopic degrees of freedom into those of the quantum simulator in a non-local manner. To illustrate the approach, we show how to efficiently cool the ferromagnetic phase of the quantum Ising model, whose excitations are domain walls, via a ``gauged cooling'' protocol in which the Ising spins are coupled to a $Z_2$ gauge field that simultaneously acts as a reservoir for removing excitations. We show that our protocol can prepare the ground states of the ferromagnetic and paramagnetic phases equally efficiently. The gauged cooling protocol naturally extends to (interacting) fermionic systems, where it is equivalent to cooling by coupling to a fermionic bath via single-fermion hopping.

This version matches the published version in Phys. Rev. Lett. DOI: https://doi.org/10.1103/PhysRevLett.134.086503

References in corpus (10)

• Simulated Quantum Computation of Molecular Energies
• The Variational Quantum Eigensolver: a review of methods and best practices
• Engineered Dissipation for Quantum Information Science
• Real- and imaginary-time evolution with compressed quantum circuits
• Hierarchy of topological order from finite-depth unitaries, measurement and feedforward
• Quantum Circuits assisted by LOCC: Transformations and Phases of Matter
• Stable Quantum-Correlated Many Body States through Engineered Dissipation
• Deterministic constant-depth preparation of the AKLT state on a quantum processor using fusion measurements
• An Alternative Approach to Quantum Imaginary Time Evolution
• Stirring by Staring: Measurement Induced Chirality

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