Demonstration of Open Quantum System Optimal Control in Dynamic Nuclear Polarization

TL;DR

This paper applies optimal control theory within an open quantum system framework to enhance dynamic nuclear polarization in NMR, achieving significantly improved nuclear spin polarization by selectively controlling DNP mechanisms.

Contribution

It introduces a quantum description of DNP and demonstrates the use of OCT to selectively enhance desired polarization transfer processes.

Findings

Order of magnitude improvement in DNP enhancement with OCT pulses

Selective suppression of competing DNP mechanisms

Experimental validation of the quantum control approach

Abstract

Dynamic nuclear polarization (DNP) is used in nuclear magnetic resonance (NMR) to transfer polarization from electron spins to nuclear spins. The resulting nuclear polarization enhancement can, in theory, be two or three orders of magnitude depending on the sample. In solid state systems, however, there are competing mechanisms of DNP, which, when occurring simultaneously, reduce the net polarization enhancement of the nuclear spin. We present a simple quantum description of DNP and apply optimal control theory (OCT) with an open quantum system framework to design pulses that select one DNP process and suppress the others. We demonstrate experimentally an order of magnitude improvement in the DNP enhancement using OCT pulses.