Fast universal two-qubit gate for neutral fermionic atoms in optical tweezers

TL;DR

This paper introduces a fast, high-fidelity two-qubit gate for neutral fermionic atoms in optical tweezers, overcoming coupling limitations and enabling scalable quantum computation.

Contribution

It proposes a novel method to perform a universal square-root-SWAP gate using controlled atomic collisions in a harmonic potential, achieving microsecond operation times.

Findings

Gate fidelity approaches unity in broad wave-packet limit

Operation time is on the microsecond scale with high fidelity

Gate duration is independent of initial atom separation

Abstract

An array of ultracold neutral atoms held in optical micro-traps is a promising platform for quantum computation. One of the major bottlenecks of this platform is the weak coupling strength between adjacent atoms, which limits the speed of two-qubit gates. Here, we present a method to perform a fast universal square-root-SWAP gate with fermionic atoms. The basic idea of the gate is to release the atoms into a harmonic potential positioned in between the two atoms. By properly tailoring the interaction parameter, the collision process between the atoms generates entanglement and yields the desired gate. We prove analytically that in the limit of broad atomic wave-packets, the fidelity of the gate approaches unity. We demonstrate numerically that with typical experimental parameters, our gate can operate on a microsecond timescale and achieves a fidelity higher than 0.998. Moreover, the gate duration is independent of the initial distance between the atoms. A gate with such features is an important milestone towards all-to-all connectivity and fault tolerance in quantum computation with neutral atoms.