# 0.5 Petabyte Simulation of a 45-Qubit Quantum Circuit

## TL;DR

This paper demonstrates the largest classical simulation of a 45-qubit quantum circuit, utilizing advanced optimization and scheduling to significantly outperform previous methods in simulation speed and scale.

## Contribution

It introduces a novel simulation approach with optimized compute kernels and scheduling, enabling the simulation of the largest quantum circuit to date on supercomputers.

## Key findings

- Simulated a 45-qubit quantum circuit using 0.5 petabytes of memory.
- Achieved over an order of magnitude improvement in simulation time.
- Demonstrated the largest quantum circuit simulation to date.

## Abstract

Near-term quantum computers will soon reach sizes that are challenging to directly simulate, even when employing the most powerful supercomputers. Yet, the ability to simulate these early devices using classical computers is crucial for calibration, validation, and benchmarking. In order to make use of the full potential of systems featuring multi- and many-core processors, we use automatic code generation and optimization of compute kernels, which also enables performance portability. We apply a scheduling algorithm to quantum supremacy circuits in order to reduce the required communication and simulate a 45-qubit circuit on the Cori II supercomputer using 8,192 nodes and 0.5 petabytes of memory. To our knowledge, this constitutes the largest quantum circuit simulation to this date. Our highly-tuned kernels in combination with the reduced communication requirements allow an improvement in time-to-solution over state-of-the-art simulations by more than an order of magnitude at every scale.