Micro-integrated crossed-beam optical dipole trap system with long-term alignment stability for mobile atomic quantum technologies

TL;DR

This paper introduces a compact, highly stable micro-integrated optical dipole trap system for cold atom experiments, demonstrating long-term stability, robustness, and effective atom trapping in a miniaturized setup suitable for mobile quantum technologies.

Contribution

The paper presents a novel micro-integrated crossed-beam optical dipole trap with long-term stability and robustness, optimized for mobile quantum applications, with detailed design and testing.

Findings

Achieved stable beam overlap with <3.4 μm difference

Demonstrated trapping of 3×10^5 atoms from a cold cloud

System remained operational with no degradation after two years

Abstract

Quantum technologies extensively use laser light for state preparation, manipulation, and readout. For field applications, these systems must be robust and compact, driving the need for miniaturized and highly stable optical setups and system integration. In this work, we present a micro-integrated crossed-beam optical dipole trap setup, the $\mu$XODT, designed for trapping and cooling $^{87}\text{Rb}$. This fiber-coupled setup operates at $1064\,\text{nm}$ wavelength with up to $2.5\,\text{W}$ optical power and realizes a free-space crossed beam geometry. The $\mu$XODT precisely overlaps two focused beams ($w_0 \approx 33\,\mu\text{m}$) at their waists in a $45^\circ$ crossing angle, achieving a position difference $\leq 3.4\,\mu\text{m}$ and 0.998 power ratio between both beams with long-term stability. We describe the design and assembly process in detail, along with optical and thermal tests with temperatures of up to $65\,^\circ C$. The system's volume of $25\,\text{ml}$ represents a reduction of more than two orders of magnitude compared to typically used macroscopic setups, while demonstrating exceptional mechanical robustness and thermal stability. The $\mu$XODT is integrated with a $^{87}\text{Rb}$ 3D MOT setup, trapping $3 \times 10^5$ atoms from a laser-cooled atomic cloud, and has shown no signs of degradation after two years of operation.