Loading atoms from a large magnetic trap to a small intra-cavity dipole trap

TL;DR

This paper demonstrates an efficient method for loading cold rubidium-87 atoms from a magnetic trap into a small intra-cavity optical dipole trap, overcoming volume mismatch issues and enabling stable, state-independent trapping for hundreds of milliseconds.

Contribution

The authors introduce an optimized technique for transferring atoms from a magnetic trap to a high-Q optical cavity trap, including controlled transport and evaporation, with real-time atom number monitoring.

Findings

High loading efficiency despite trap volume mismatch

Stable trapping of atoms for several hundred milliseconds

Demonstration of state-independent trapping using a repumper laser

Abstract

We show that an optimized loading of a cold ensemble of rubidium-87 atoms from a magnetic trap into an optical dipole trap sustained by a single, far-red-detuned mode of a high-Q optical cavity can be efficient despite the large volume mismatch of the traps. The magnetically trapped atoms are magnetically transported to the vicinity of the cavity mode and released from the magnetic trap in a controlled way meanwhile undergoing an evaporation period. Large number of atoms get trapped in the dipole potential for several hundreds of milliseconds. We monitor the number of atoms in the mode volume by a second tone of the cavity close to the atomic resonance. While this probe tone can pump atoms to another ground state uncoupled to the probe, we demonstrate state-independent trapping by applying a repumper laser.