Pilot-Wave Simulator: Exact Classical Sampling from Ideal and Noisy Quantum Circuits up to Hundreds of Qubits

TL;DR

This paper introduces an exact classical sampling method for large-scale quantum circuits, including noisy ones, using tensor networks and Markov processes, enabling simulation of up to hundreds of qubits.

Contribution

It presents a novel exact sampling algorithm combining tensor networks and Markov processes, capable of simulating large quantum circuits with noise.

Findings

Successfully sampled from ideal and noisy QAOA circuits with up to 476 qubits.

Enabled validation of quantum algorithm assumptions at unprecedented scale.

Expanded the scope of classical simulation for quantum circuit research.

Abstract

Quantum circuit simulators running on classical computers offer a vital platform for designing, testing, and optimizing quantum algorithms, driving innovation despite limited access to real quantum hardware. However, their scalability is inherently constrained by exponential memory and computational overhead, which restricts accurate simulation of large-scale quantum circuits and often results in approximate output distributions. Here, we propose an exact sampling algorithm that integrates tensor network contraction techniques with a Markov process, wherein a classical state evolves according to the local structure of the quantum circuit. As a demonstration, we target the challenge of generating samples from ideal and noisy QAOA circuits with up to 476 qubits, incorporating both depolarizing and amplitude damping noise models. These results enable further validation of several assumptions and conjectures at a scale previously out of reach, significantly expanding the scope of classical simulation in quantum algorithm research.