Quantum gates in mesoscopic atomic ensembles based on adiabatic passage and Rydberg blockade

TL;DR

This paper introduces robust quantum gate protocols for atomic ensembles using adiabatic passage techniques and Rydberg blockade, enabling reliable quantum operations regardless of atom number variations.

Contribution

It develops geometric phase compensation schemes for adiabatic passage, allowing universal quantum gates in atomic ensembles with arbitrary atom counts.

Findings

Protocols achieve atom-number independent state transfer.

Double pulse sequences enable universal single- and two-qubit gates.

Phase and amplitude control ensures high-fidelity quantum operations.

Abstract

We present schemes for geometric phase compensation in adiabatic passage which can be used for the implementation of quantum logic gates with atomic ensembles consisting of an arbitrary number of strongly interacting atoms. Protocols using double sequences of stimulated Raman adiabatic passage (STIRAP) or adiabatic rapid passage (ARP) pulses are analyzed. Switching the sign of the detuning between two STIRAP sequences, or inverting the phase between two ARP pulses, provides state transfer with well defined amplitude and phase independent of atom number in the Rydberg blockade regime. Using these pulse sequences we present protocols for universal single-qubit and two-qubit operations in atomic ensembles containing an unknown number of atoms.