Vector spin polarization evolution determined in an entangled muon-fluorine system under pulsed excitation

TL;DR

This paper introduces a novel RF muon technique that enables three-dimensional vector readout of muon spin polarization in an entangled fluorine system, allowing detailed control and observation of spin dynamics.

Contribution

It presents a new RF muon method for three-dimensional vector readout and control of entangled muon-fluorine spins, surpassing traditional NMR capabilities.

Findings

Demonstrated muon spin echo controlled by dipolar coupling

Achieved double resonance addressing both muon and fluorine spins

Showed advantages of RF muon techniques over single NMR experiments

Abstract

A spin-polarized muon implanted into a fluoride forms a coupled F--$\mu$--F complex in which the muon spin and neighbouring fluorine nuclear spins become entangled. Here we apply radio-frequency (RF) excitation to this coupled system and use the three-dimensional distribution of emitted positrons to reconstruct the time-dependent evolution of the muon spin polarization. This three-dimensional readout, using single spin detection, is not possible in a single NMR experiment and demonstrates significant advantages that are achieved by using RF muon techniques. We demonstrate the application of this vector-readout method to the experimental observation of a muon spin echo signal that is controlled by the dipolar coupling to fluorine, as well as to a double resonance experiment, in which we use pulses tuned to separate frequencies to address both the muon and fluorine spins. This targeted approach, in which selective RF pulses can control the muon spin and other spins to which it is coupled, provides a novel route for probing systems of entangled spins.