Coherent cancellation of geometric phase for the OH molecule in external fields

TL;DR

This paper calculates the geometric phases of the OH molecule in oscillating magnetic and electric fields, identifying conditions where these phases cancel, which is crucial for reducing errors in precision measurements.

Contribution

It provides an exact calculation of geometric phases for the OH molecule in time-varying fields using an analytic Hamiltonian solution, revealing conditions for phase cancellation.

Findings

Geometric phases depend richly on field rotation rates.

Certain rotation rates lead to zero or canceled relative geometric phases.

Results help improve accuracy in precision spectroscopy of OH.

Abstract

The OH molecule in its ground state presents a versatile platform for precision measurement and quantum information processing. These applications depend vitally on the accurate measurement of transition energies between the OH levels. Significant sources of systematic errors in these measurements are shifts based on the geometric phase arising from the magnetic and electric fields used for manipulating OH. In this article, we present these geometric phases for fields that vary harmonically in time, as in the Ramsey technique. Our calculation of the phases is exact within the description provided by our recent analytic solution of an effective Stark-Zeeman Hamiltonian for the OH ground state. This Hamiltonian has earlier been shown to model experimental data accurately. We find that the OH geometric phases exhibit rich structure as a function of the field rotation rate. Remarkably, we find rotation rates where the geometric phase accumulated by a specific state is zero, or where the relative geometric phase between two states vanishes. We expect these findings to be of importance to precision experiments on OH involving time-varying fields. More specifically, our analysis quantitatively characterizes an important item in the error budget for precision spectroscopy of ground state OH.