A simplified M{\o}lmer-S{\o}rensen gate for the trapped ion quantum computer

TL;DR

This paper introduces a simplified version of the Molmer-Sorensen gate for trapped ion quantum computers, using monochromatic light to create entanglement more robustly against thermal fluctuations.

Contribution

The authors propose a new method for implementing the MS gate with monochromatic light, reducing sensitivity to thermal phonon fluctuations compared to the original scheme.

Findings

The proposed gate has comparable execution time to the original MS gate.

Numerical calculations show increased robustness against thermal fluctuations.

The scheme simplifies implementation by using individual monochromatic light fields.

Abstract

We discuss how to simplify the Molmer-Sorensen (MS) gate which is used for the trapped ion quantum computer. The original MS gate is implemented by illuminating two ions with bichromatic coherent light fields separately at the same time. In this paper, we propose a method for transforming a separable state of two ions into one of the Bell states by illuminating the two ions with monochromatic coherent light fields individually and this point is the advantage of our scheme over the original MS gate. The length of the execution time of our proposed gate is comparable to that of the original MS gate, however, numerical calculations show that our proposed gate is weakly sensitive to thermal fluctuations of the phonons. By giving another example of a simple two-ion gate that can generate entanglement but is strongly vulnerable to thermal fluctuations, we show that our simplified MS gate is more marked than usual.