Closing the "Quantum Supremacy" Gap: Achieving Real-Time Simulation of a Random Quantum Circuit Using a New Sunway Supercomputer

TL;DR

This paper presents a high-performance tensor-based simulator for random quantum circuits on the Sunway supercomputer, achieving unprecedented simulation speed and reducing Google's Sycamore sampling time from years to minutes.

Contribution

It introduces novel slicing, parallelization, and mixed-precision techniques that significantly enhance classical simulation capabilities for large quantum circuits.

Findings

Simulates 10x10 qubit circuits with depth 42+1 using 42 million cores.

Achieves 1.2 Eflops performance in single-precision.

Reduces Google Sycamore sampling time from 10,000 years to 304 seconds.

Abstract

We develop a high-performance tensor-based simulator for random quantum circuits(RQCs) on the new Sunway supercomputer. Our major innovations include: (1) a near-optimal slicing scheme, and a path-optimization strategy that considers both complexity and compute density; (2) a three-level parallelization scheme that scales to about 42 million cores; (3) a fused permutation and multiplication design that improves the compute efficiency for a wide range of tensor contraction scenarios; and (4) a mixed-precision scheme to further improve the performance. Our simulator effectively expands the scope of simulatable RQCs to include the 10*10(qubits)*(1+40+1)(depth) circuit, with a sustained performance of 1.2 Eflops (single-precision), or 4.4 Eflops (mixed-precision)as a new milestone for classical simulation of quantum circuits; and reduces the simulation sampling time of Google Sycamore to 304 seconds, from the previously claimed 10,000 years.