Circuit connectivity boosts by quantum-classical-quantum interfaces

Author(s)

Wiersema, Roeland ; Guerini, Leonardo ; Carrasquilla, Juan Felipe ; Aolita, Leandro

• Document type: Journal article
• Source: PHYSICAL REVIEW RESEARCH; v. 4, n. 4, p. 14-pg., 2022-12-29.

Abstract

High-connectivity circuits are a major roadblock for current quantum hardware. We propose a hybrid classical-quantum algorithm to simulate such circuits without SWAP-gate ladders. As the main technical tool, we introduce quantum-classical-quantum interfaces. These replace an experimentally problematic gate (e.g., a long-range one) with single-qubit random measurements followed by state preparations sampled according to a classical quasiprobability simulation of the noiseless gate. Each interface introduces a multiplicative statistical overhead which, remarkably, is independent of the on-chip qubit distance. Hence, by applying interfaces to the longest-range gates in a target circuit, significant reductions in circuit depth and gate infidelity can be attained. We numerically show the efficacy of our method for a Bell-state circuit for two increasingly distant qubits and a variational ground-state solver for the transverse-field Ising model on a ring. Our findings provide a versatile toolbox for error-mitigation and circuit boosts tailored for noisy, intermediate-scale quantum computation. (AU)

• FAPESP's process: 18/04208-9 - Quantum measurement simulability and applications to Bell nonlocality
• Grantee: Leonardo Guerini de Souza
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 16/01343-7 - ICTP South American Institute for Fundamental Research: a regional center for theoretical physics
• Grantee: Nathan Jacob Berkovits
• Support Opportunities: Special Projects