Enhanced coupling of electron and nuclear spins by quantum tunneling resonances

TL;DR

This paper proposes a mechanism leveraging quantum tunneling resonances to significantly accelerate electron-nuclear spin transfer in noble gases, potentially improving their practical usability.

Contribution

It introduces a controllable method to enhance spin transfer rates via resonant binary collisions, demonstrating a universal and substantial increase in spin-exchange efficiency.

Findings

Resonant enhancement of spin-exchange cross section by up to six orders of magnitude.

Two orders of magnitude increase in polarization rate-coefficient.

Universal applicability across various noble gases.

Abstract

Noble-gas spins feature hours long coherence times owing to their great isolation from the environment, and find practical usage in various applications. However, this isolation leads to extremely slow preparation times, relying on weak spin transfer from an electron-spin ensemble. Here we propose a controllable mechanism to enhance this transfer rate. We analyze the spin dynamics of helium-3 atoms with hot, optically-excited potassium atoms and reveal the formation of quasi-bound states in resonant binary collisions. We find a resonant enhancement of the spin-exchange cross section by up to six orders of magnitude and two orders of magnitude enhancement for the thermally averaged, polarization rate-coefficient. We further examine the effect for various other noble gases and find that the enhancement is universal. We outline feasible conditions under which the enhancement may be experimentally observed and practically utilized.