Optimal control of Raman pulse sequences for atom interferometry

Jack Saywell,Ilya Kuprov,Mohammad Belal,Tim Freegarde,Max Carey

doi:10.1088/1361-6455/ab6df6

Jack Saywell, Ilya Kuprov + Show 3 more

Open Access

https://doi.org/10.1088/1361-6455/ab6df6

Copy DOI

Abstract

We present the theoretical design and experimental implementation of mirror and beamsplitter pulses that improve the fidelity of atom interferometry and increase its tolerance of systematic inhomogeneities. These pulses are designed using the GRAPE optimal control algorithm and demonstrated experimentally with a cold thermal sample of 85Rb atoms. We first show a stimulated Raman inversion pulse design that achieves a ground hyperfine state transfer efficiency of 99.8(3)%, compared with a conventional π pulse efficiency of 75(3)%. This inversion pulse is robust to variations in laser intensity and detuning, maintaining a transfer efficiency of 90% at detunings for which the π pulse fidelity is below 20%, and is thus suitable for large momentum transfer interferometers using thermal atoms or operating in non-ideal environments. We then extend our optimization to all components of a Mach–Zehnder atom interferometer sequence and show that with a highly inhomogeneous atomic sample the fringe visibility is increased threefold over that using conventional π and π/2 pulses.

Highlights

Atom interferometers [1] are the matterwave analogues of optical interferometers
We present the theoretical design and experimental implementation of mirror and beamsplitter pulses that improve the fidelity of atom interferometry and increase its tolerance of systematic inhomogeneities
We first show a stimulated Raman inversion pulse design that achieves a ground hyperfine state transfer efficiency of 99.8(3)%, compared with a conventional π pulse efficiency of 75(3)%. This inversion pulse is robust to variations in laser intensity and detuning, maintaining a transfer efficiency of 90% at detunings for which the π pulse fidelity is below 20%, and is suitable for large momentum transfer interferometers using thermal atoms or operating in non-ideal environments

Summary

Introduction

Atom interferometers [1] are the matterwave analogues of optical interferometers. Slow, massive atomic wavepackets replace the photons that are divided to follow separate spatial paths before being recombined to produce interference; and, in place of the mirrors and beamsplitters, carefully-timed resonant laser pulses split, steer and recombine the wavepackets. 53 (2020) 085006 initial momentum distribution [15, 16], with Bloch oscillations [17,18,19] and Bragg diffraction [20,21,22] demonstrating the greatest separation, but filtering the atomic sample in this way to reduce the effects of inhomogeneities and cloud expansion involves lengthier preparation and causes a fall in the signal-tonoise ratio because fewer atoms are measured For applications such as inertial navigation where both the sensitivity and repetition rate are important, techniques are required that are more tolerant of experimental and environmental inhomogeneities in laser intensity, magnetic field, atom velocity and radiative coupling strength. This is, to our knowledge, the first demonstration of shaped individual beamsplitter pulses preparing momentum superpositions being used to improve the contrast of an atom interferometer

Theoretical system and optimization approach

Measures of pulse performance

Results of optimizations

Experimental procedure

Results