Inducing Resonant Interactions in Ultracold Atoms with a Modulated Magnetic Field

TL;DR

This paper introduces a novel method to resonantly enhance interactions in ultracold atoms using a modulated magnetic field, bypassing traditional Feshbach resonances and allowing precise control over atom interactions and losses.

Contribution

The work demonstrates a new mechanism for controlling ultracold atom interactions via oscillating magnetic fields, providing tunable resonance parameters without relying on Feshbach resonances.

Findings

Resonant enhancement of the real part of the scattering length without significant atom loss.

Control of resonance parameters through oscillation amplitude.

Universal behavior of resonance parameters for shallow bound states.

Abstract

In systems of ultracold atoms, pairwise interactions can be resonantly enhanced by a new mechanism which does not rely upon a magnetic Feshbach resonance. In this mechanism, interactions are controlled by tuning the frequency of an oscillating parallel component of the magnetic field close to the transition frequency between the scattering atoms and a two-atom bound state. The real part of the resulting s-wave scattering length $a$ is resonantly enhanced when the oscillation frequency is close to the transition frequency. The resonance parameters can be controlled by varying the amplitude of the oscillating field. The amplitude also controls the imaginary part of $a$ which arises because the oscillating field converts atom pairs into molecules. The real part of $a$ can be made much larger than the background scattering length without introducing catastrophic atom losses from the imaginary part. For the case of a shallow bound state in the scattering channel, the dimensionless resonance parameters are universal functions of the dimensionless oscillation amplitude.