Generalized multichannel optical theorem: Coherent control of the total scattering cross section

TL;DR

This paper extends the optical theorem to superposition states, enabling quantum interference control of total scattering cross sections in ultracold molecular and atomic collisions, with potential for experimental realization.

Contribution

It introduces a generalized optical theorem accounting for superposition states, revealing new interference effects and control mechanisms in quantum scattering.

Findings

Control index shows extensive manipulation of scattering cross sections is possible.

Theoretical framework applies to ultracold oxygen and rubidium collisions.

Potential for first experimental demonstration of quantum interference control.

Abstract

The optical theorem is a fundamental aspect of quantum scattering theory. Here, we generalize this theorem to the case where the incident scattering state is a superposition of internal states of the collision partners, introducing additional interference contributions and, e.g., providing a route to control the total integral cross section. As in its standard form, forward scattering plays an essential role in the generalized optical theorem, but with interference terms being related to the inelastic forward scattering amplitudes between states in the initial superposition. Using the resultant control index, we show that extensive control is possible over ultracold collisions of oxygen molecules in their rovibrational ground states, and of 85Rb-85Rb collisions, promising systems for the first experimental demonstration of the quantum interference control of the total scattering cross section.