Electric field-dependent dynamic polarizability and "magic" conditions for optical trapping of polar molecules

TL;DR

This paper explores how electric fields and laser light influence the trapping potential of ultracold polar molecules, identifying conditions where the Stark shift becomes independent of external fields, which could improve precision in quantum applications.

Contribution

It introduces a method to control the AC Stark shift of rotational states in ultracold polar molecules using electric and laser fields, revealing 'magic' conditions for trapping.

Findings

Identification of 'magic' electric field strengths

Discovery of a 'magic angle' for trapping

Control of Stark shift independence from external fields

Abstract

Selection of "magic" trapping conditions with ultracold atoms or molecules, where pairs of internal states experience identical trapping potentials, brings substantial benefits to precision measurements and quantum computing schemes. Working at such conditions could ensure that detrimental effects of inevitable inhomogeneities across an ultracold sample are significantly reduced. However, this aspect of confinement remains unexplored for ultracold polar molecules. Here, we present means to control the AC Stark shift of rotational states of ultracold polar molecules, when subjected to both trapping laser light and an external electric field. We show that both the strength and relative orientation of the two fields influence the trapping potential. In particular, we predict "magic electric field strengths" and a "magic angle", where the Stark shift is independent of the DC external field and rotational states of the molecule.