Quantum supremacy with spin squeezed atomic ensembles

TL;DR

This paper proposes a method to achieve quantum supremacy using atomic ensembles with spin squeezing, basis rotations, and measurements, demonstrating a complexity that surpasses classical capabilities.

Contribution

It introduces a novel approach leveraging atomic ensembles and spin squeezing to reach quantum supremacy, with a scalable complexity analysis.

Findings

Probability distribution approaches Porter-Thomas distribution

Sampling problem is #P-hard with complexity scaling as (N+1)^M

Implementation feasible with atomic ensembles, enabling quantum supremacy

Abstract

We propose a method to achieve quantum supremacy using ensembles of qubits, using only spin squeezing, basis rotations, and Fock state measurements. Each ensemble is assumed to be controllable only with its total spin. Using a repeated sequence of random basis rotations followed by squeezing, we show that the probability distribution of the final measurements quickly approaches a Porter-Thomas distribution. We show that the sampling probability can be related to a #P-hard problem with a complexity scaling as $(N+1)^M$, where $N$ is the number of qubits in an ensemble and $ M $ is the number of ensembles. The scheme can be implemented with hot or cold atomic ensembles. Due to the large number of atoms in typical atomic ensembles, this allows access to the quantum supremacy regime with a modest number of ensembles or gate depth.