Broadband excitation by chirped pulses: application to single electron spins in diamond

I Niemeyer,H Abe,S Onoda,J Zhang,J Isoya,T Yamamoto,T Taniguchi,F Jelezko,T Ohshima,T Teraji,J H Shim,D Suter

doi:10.1088/1367-2630/15/3/033027

Abstract

Pulsed excitation of broad spectra requires very high field strengths if monochromatic pulses are used. If the corresponding high power is not available or not desirable, the pulses can be replaced by suitable low-power pulses that distribute the power over a wider bandwidth. As a simple case, we use microwave pulses with a linear frequency chirp. We use these pulses to excite spectra of single nitrogen–vacancy centres in a Ramsey experiment. Compared to the conventional Ramsey experiment, our approach increases the bandwidth by at least an order of magnitude. Compared to the conventional continuous wave-ODMR experiment, the chirped Ramsey experiment does not suffer from power broadening and increases the resolution by at least an order of magnitude. As an additional benefit, the chirped Ramsey spectrum contains not only ‘allowed’ single quantum transitions, but also ‘forbidden’ zero- and double quantum transitions, which can be distinguished from the single quantum transitions by phase-shifting the readout pulse with respect to the excitation pulse or by variation of the external magnetic field strength.

Highlights

Nitrogen-vacancy (NV) defect centers in diamond are promising candidates for quantum information processing [1], magnetometry [2] and electrometry [3]
In each spectrum of the figure, we list the splitting between the single quantum transitions, which corresponds to the magnetic field component along the symmetry axis of the center, measured in frequency units
We have introduced a new experimental technique for measuring broad spectra of single electron spins

Summary

Introduction

Nitrogen-vacancy (NV) defect centers in diamond are promising candidates for quantum information processing [1], magnetometry [2] and electrometry [3]. The strength of the hyperfine interaction depends on the position of the nuclear spin [9] and reaches a maximum of 130 MHz for a 13C in a nearest-neighbor lattice site [1, 10] Measuring these couplings requires the recording of spectra that cover a frequency range larger than the sum of all hyperfine coupling constants. We present an experimental scheme that avoids power broadening by using the Ramsey approach of free precession and avoids the requirement of strong microwave fields by using excitation pulses that cover the full bandwidth with very low power We achieve this by scanning the frequency over the full spectral range. Different types of transitions can be distinguished by appropriate shifts in the relative phases of the excitation and readout pulses

Mathematical Descriptions

Setup and Samples

Conclusions