Quantum Simulation via Stochastic Combination of Unitaries

TL;DR

This paper introduces a new quantum simulation framework that uses ensembles of low-depth circuits to efficiently simulate quantum channels and open systems, reducing resource requirements significantly.

Contribution

The authors propose a stochastic combination of unitaries approach for quantum simulation, enabling efficient simulation of open systems and Hamiltonian dynamics with fewer resources.

Findings

Successfully prepared damped GHZ states on ibm_hanoi.

Developed two Hamiltonian simulation algorithms with reduced resource needs.

Achieved asymptotic independence of spectral precision in simulations.

Abstract

Quantum simulation algorithms often require numerous ancilla qubits and deep circuits, prohibitive for near-term hardware. We introduce a framework for simulating quantum channels using ensembles of low-depth circuits in place of many-qubit dilations. This naturally enables simulations of open systems, which we demonstrate by preparing damped many-qubit GHZ states on ibm_hanoi. The technique further inspires two Hamiltonian simulation algorithms with asymptotic independence of the spectral precision, reducing resource requirements by several orders of magnitude for a benchmark system.