Dipolar atomic spin ensembles in a double-well potential

TL;DR

This paper experimentally investigates the spin dynamics of ultracold chromium atom ensembles in a double-well trap, revealing metastable spin domains, classical dipolar behavior, and measuring the s-wave scattering length for chromium atoms.

Contribution

It demonstrates the creation of metastable spin domains in a double-well setup and measures the s-wave scattering length for chromium in a new molecular channel.

Findings

Engineered spin domains are metastable due to dipolar interactions.

No inter-cloud dipolar spin-exchange observed, indicating classical behavior.

Measured s-wave scattering length for 52Cr atoms as a_0=13.5^{+11}_{-10.5}a_B.

Abstract

We experimentally study the spin dynamics of mesoscopic ensembles of ultracold magnetic spin-3 atoms located in two separated wells of an optical dipole trap. We use a radio-frequency sweep to selectively flip the spin of the atoms in one of the wells, which produces two separated spin domains of opposite polarization. We observe that these engineered spin domains are metastable with respect to the long-range magnetic dipolar interactions between the two ensembles. The absence of inter-cloud dipolar spin-exchange processes reveals a classical behavior, in contrast to previous results with atoms loaded in an optical lattice. When we merge the two subsystems, we observe spin-exchange dynamics due to contact interactions which enable the first determination of the s-wave scattering length of 52Cr atoms in the S=0 molecular channel a_0=13.5^{+11}_{-10.5}a_B (where a_B is the Bohr radius).