Rotation-inspired circuit cut optimization

TL;DR

RICCO is a novel circuit cut optimization method that reduces classical post-processing overhead by applying unitary rotations at cut locations, demonstrated through classical simulation of VQE.

Contribution

It introduces a rotation-based optimization approach to improve circuit cutting efficiency, a new technique in quantum circuit decomposition.

Findings

RICCO reduces post-processing complexity compared to existing methods.

Classical simulation shows RICCO's effectiveness in VQE applications.

Rotation-based optimization improves quantum circuit decomposition efficiency.

Abstract

Recent works have demonstrated that large quantum circuits can be cut and decomposed into smaller clusters of quantum circuits with fewer qubits that can be executed independently on a small quantum computer. Classical post-processing then combines the results from each cluster to reconstruct the output of the original quantum circuit. However, the runtime for such hybrid quantum-classical algorithms is exponential in the number of cuts on a circuit. We propose Rotation-Inspired Circuit Cut Optimization (RICCO), an alternative method which reduces the post-processing overhead of circuit cutting, at the cost of having to solve an optimization problem. RICCO introduces unitary rotations at cut locations to rotate the quantum state such that expectation values with respect to one set of observables are maximized and others are set to zero. We demonstrate practical application of RICCO to VQE by classically simulating a small instance of VQE and comparing it to one of the existing circuit-cutting methods.