Two-qubit quantum gates with minimal pulse sequences

TL;DR

This paper presents a method for implementing high-fidelity two-qubit entangling gates using minimal pulse sequences in trapped atom systems, with analysis of errors and optimization strategies.

Contribution

It introduces a novel approach using single and structured pulses for entangling gates, optimizing parameters via Diophantine equations, and analyzing error sources.

Findings

Fidelity can be improved by stronger fields despite inherent limitations.

Two-pulse sequences offer more mechanisms for high-fidelity gates.

Main error source is fluctuations in peak intensity affecting gate fidelity.

Abstract

Working with trapped atoms at close distance to each other, we show that one can implement entangling gates based on non-independent qubits using a single pulse per qubit, or a single structured pulse. The optimal parameters depend on approximate solutions of Diophantine equations, causing the fidelity to never be exactly perfect, even under ideal conditions, although the errors can be made arbitrarily smaller at the cost of stronger fields. We fully characterize the mechanism by which the gates operate, and show that the main source of error in realistic implementations comes from fluctuations in the peak intensity, which especially damages the fidelity of the gates that use stronger fields. Working with two-pulse sequences, instead of one, enables the use of a plethora of mechanisms and a broad range of optimal parameters to choose from, to achieve high-fidelity gates.