Many-body kinetics of dynamic nuclear polarization by the cross effect

A Karabanov,I Lesanovsky,F Raimondi,W Köckenberger,D Wiśniewski

doi:10.1103/physreva.97.031404

Abstract

Dynamic nuclear polarization (DNP) is an out-of-equilibrium method for generating non-thermal spin polarization which provides large signal enhancements in modern diagnostic methods based on nuclear magnetic resonance. A particular instance is cross effect DNP, which involves the interaction of two coupled electrons with the nuclear spin ensemble. Here we develop a theory for this important DNP mechanism and show that the non-equilibrium nuclear polarization build-up is effectively driven by three-body incoherent Markovian dissipative processes involving simultaneous state changes of two electrons and one nucleus. Our theoretical approach allows for the first time simulations of the polarization dynamics on an individual spin level for ensembles consisting of hundreds of nuclear spins. The insight obtained by these simulations can be used to find optimal experimental conditions for cross effect DNP and to design tailored radical systems that provide optimal DNP efficiency.

Highlights

Dynamic nuclear polarization (DNP) is an out-of-equilibrium method for generating non-thermal spin polarization which provides large signal enhancements in modern diagnostic methods based on nuclear magnetic resonance
The sensitivity of nuclear magnetic resonance (NMR) can be significantly enhanced by dynamic nuclear polarization (DNP), an out-of-equilibrium method that involves the microwave driven transfer of the much stronger polarization of unpaired electrons to the nuclear spin ensemble via the electron nuclear hyperfine interaction [1,2,3]
We expect our insights to be applicable to the non-equilibrium dynamics of nitrogen-vacancies in diamond [32, 33], which is becoming a popular platform for the implementation of quantum sensing and diagnostics

Summary

Introduction

Dynamic nuclear polarization (DNP) is an out-of-equilibrium method for generating non-thermal spin polarization which provides large signal enhancements in modern diagnostic methods based on nuclear magnetic resonance. Under this condition the first electron is saturated more efficiently than the second and the arising polarization difference between the two is transferred to a coupled nuclear spin by a three-spin process.

Results

Conclusion