Metastable Feshbach Molecules in High Rotational States

TL;DR

This paper reports the creation of metastable Cs2 Feshbach molecules in high rotational states that are stable for seconds and can be dissociated on demand by magnetic field tuning.

Contribution

It demonstrates the experimental realization of high rotational state Feshbach molecules with metastability due to centrifugal barriers, enabling controlled dissociation.

Findings

Molecules are stable for about one second against spontaneous decay.

Dissociation can be precisely controlled via magnetic field tuning.

Metastability arises from large centrifugal barriers and weak coupling to low rotational states.

Abstract

We experimentally demonstrate Cs2 Feshbach molecules well above the dissociation threshold, which are stable against spontaneous decay on the timescale of one second. An optically trapped sample of ultracold dimers is prepared in an l-wave state and magnetically tuned into a region with negative binding energy. The metastable character of these molecules arises from the large centrifugal barrier in combination with negligible coupling to states with low rotational angular momentum. A sharp onset of dissociation with increasing magnetic field is mediated by a crossing with a g-wave dimer state and facilitates dissociation on demand with a well defined energy.