# Forbidden coherent transfer observed between two realizations of quasi-harmonic spin system

## TL;DR

This paper demonstrates forbidden coherent transfer between two quasi-harmonic spin system realizations using $^{55}$Mn$^{2+}$, showing Rabi oscillations and potential for fast quantum information exchange.

## Contribution

It introduces a method to induce and observe forbidden coherent transfer between two pseudo-harmonic levels in a multi-level spin system.

## Key findings

- Observed Rabi oscillations between two coupled quasi-harmonic spin systems.
- Coupling strength exceeds decoherence rate, enabling fast information exchange.
- Used crystalline anisotropy to induce forbidden nuclear transitions.

## Abstract

The multi-level system $^{55}$Mn$^{2+}$ is used to generate two pseudo-harmonic level systems, as representations of the same electronic sextuplet at different nuclear spin projections. The systems are coupled using a forbidden nuclear transition induced by the crystalline anisotropy. We demonstrate Rabi oscillations between the two representations in conditions similar to two coupled quasi-harmonic quantum oscillators. Rabi oscillations are performed at a detuned pumping frequency which matches energy difference between electro-nuclear states of different oscillators. We measure a coupling stronger than the decoherence rate, to indicate the possibility fast information exchange between the systems.