Controlling collisional decoherence of ultracold molecules in superposition states by an external magnetic field

TL;DR

This paper demonstrates how external magnetic fields can control collisional decoherence in ultracold molecules by tuning scattering lengths near Feshbach resonances, enabling suppression or enhancement of decoherence.

Contribution

It provides analytical expressions for decoherence suppression and proposes a method to measure scattering lengths in excited states using Feshbach resonances.

Findings

Decoherence can be suppressed when real and imaginary parts of scattering lengths are equal.

Magnetic fields near Feshbach resonances can dramatically alter decoherence rates.

A new measurement method for scattering lengths in excited states is proposed.

Abstract

We present expressions demonstrating that collisional decoherence of ultracold atoms or molecules in a coherent superposition of non-degenerate quantum states is suppressed when both the real and imaginary parts of the scattering lengths for the states in the coherent superposition are equal. We show that the rate of collisional decoherence can be enhanced or suppressed by varying an external magnetic field near a Feshbach resonance. For some resonances, the suppression is very dramatic. We propose a method for measuring the scattering length of ultracold particles in excited quantum states exhibiting Feshbach resonances.