1 research outputs found
Gauged cooling of topological excitations and emergent fermions on quantum simulators
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
system's 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 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