Shaped pulses for transient compensation in quantum-limited electron spin resonance spectroscopy.

Sebastian Probst,Bartolo Albanese,Steffen J Glaser,Denis Vion,Daniel Esteve,Patrice Bertet,Quentin Ansel,Reinier Heeres,Emanuele Albertinale,Vishal Ranjan,Dominique Sugny

doi:10.1016/j.jmr.2019.04.008

Abstract

In high sensitivity inductive electron spin resonance spectroscopy, superconducting microwave resonators with large quality factors are employed. While they enhance the sensitivity, they also distort considerably the shape of the applied rectangular microwave control pulses, which limits the degree of control over the spin ensemble. Here, we employ shaped microwave pulses compensating the signal distortion to drive the spins faster than the resonator bandwidth. This translates into a shorter echo, with enhanced signal-to-noise ratio. The shaped pulses are also useful to minimize the dead-time of our spectrometer, which allows to reduce the wait time between successive drive pulses.

Highlights

Electron spin resonance (ESR) spectroscopy allows to analyze the composition and structure of paramagnetic samples [1]
We show that shaped pulses enable cavity ringdown suppression, wide-band spin manipulation, as well as signal-to-noise-ratio enhancement
Shaped pulse characterization In NMR and ESR experiments using shaped pulses, the intracavity field is often characterized by inserting a pickup coil in the resonator [3,9,17], or by using the Rabi nutation of the spins [5]

Summary

Introduction

Electron spin resonance (ESR) spectroscopy allows to analyze the composition and structure of paramagnetic samples [1]. In the inductive detection method, the sample is coupled to a resonant microwave cavity of frequency x0. After being driven by appropriate microwave pulse sequences, their Larmor precession dynamics induces the subsequent emission of weak microwave spin-echo signals, which carry information on the properties of the paramagnetic species present in the sample. The cavity has several roles in this pproffiffifficffi ess. It amplifies the B1 driving field by a factor proportional to Q (Q being the resonator quality factor), which lowers the incident microwave power requirements. It amplifies the emitted spin-echo signals by the same factor, which enhances detection sensitivity

Methods

Results

Conclusion