Magnetic dipolar interaction between hyperfine clock states in a planar alkali Bose gas

TL;DR

This paper demonstrates that hyperfine clock states in a planar alkali Bose gas exhibit magnetic dipole-dipole interactions, which are tunable and have implications for precision measurements, despite their low magnetic sensitivity.

Contribution

It reveals the presence and tunability of magnetic dipole interactions between non-magnetic clock states in a Bose gas, a novel finding in atomic physics.

Findings

Magnetic dipole-dipole interactions are observable between clock states.

Interactions are isotropic and extensively tunable.

Constraints on s-wave scattering lengths involving clock states are established.

Abstract

In atomic systems, clock states feature a zero projection of the total angular momentum and thus a low sensitivity to magnetic fields. This makes them widely used for metrological applications like atomic fountains or gravimeters. Here, we show that a mixture of two such non-magnetic states still display magnetic dipole-dipole interactions. Using high resolution spectroscopy of a planar gas of $^{87}$Rb atoms with a controlled in-plane shape, we explore the effective isotropic and extensive character of these interactions and demonstrate their tunability. Our measurements set strong constraints on the relative values of the s-wave scattering lengths $a_{ij}$ involving the two clock states.