Long rotational coherence times of molecules in a magnetic trap

TL;DR

This paper demonstrates that certain laser-coolable molecules, like CaF, can maintain long rotational coherence times in magnetic traps due to their insensitivity to magnetic field fluctuations, enabling potential quantum applications.

Contribution

The study identifies and experimentally verifies rotational transitions in molecules with exceptionally low magnetic sensitivity, achieving coherence times of several milliseconds in magnetic traps.

Findings

CaF exhibits a transition with sensitivity below 5 Hz G$^{-1}$

Achieved a rotational coherence time of 6.4 ms in a magnetic trap

Simulations indicate potential extension of coherence time to over 1 second

Abstract

Polar molecules in superpositions of rotational states exhibit long-range dipolar interactions, but maintaining their coherence in a trapped sample is a challenge. We present calculations that show many laser-coolable molecules have convenient rotational transitions that are exceptionally insensitive to magnetic fields. We verify this experimentally for CaF where we find a transition with sensitivity below 5 Hz G$^{-1}$ and use it to demonstrate a rotational coherence time of 6.4(8) ms in a magnetic trap. Simulations suggest it is feasible to extend this to more than 1 s using a smaller cloud in a biased magnetic trap.