Exponential Error Suppression for Near-Term Quantum Devices

Suppressing noise in physical systems is of fundamental importance. As quantum computers mature, error correcting codes (QECs) will be adopted order to suppress errors any desired level. However the noisy, intermediate-scale (NISQ) era, complexity and scale required adopt even smallest QEC prohibitive: a single logical qubit needs encoded into many thousands qubits. Here we show that, for crucial case estimating expectation values observables (key almost all NISQ algorithms) one can indeed achieve an effective exponential suppression. We take n independently prepared circuit outputs create state whose symmetries prevent from contributing bias expected value. The approach very well suited current near-term devices as it modular main computation requires only shallow that bridges copies immediately prior measurement. Using no more than four copies, confirm suppression below 10?6 circuits consisting several hundred noisy gates (2-qubit gate 0.5%) numerical simulations validating our approach.5 MoreReceived 1 February 2021Revised 3 June 2021Accepted 30 July 2021DOI:https://doi.org/10.1103/PhysRevX.11.031057Published by American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution this work must maintain attribution author(s) published article’s title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasQuantum algorithmsQuantum computationQuantum Information