Efficient Electrical Spin Readout ofNV−Centers in Diamond

Abstract

Using pulsed photoionization the coherent spin manipulation and echo formation of ensembles of NV -centers in diamond are detected electrically realizing contrasts of up to 17 %. The underlying spin-dependent ionization dynamics are investigated experimentally and compared to Monte-Carlo simulations. This allows the identification of the conditions optimizing contrast and sensitivity which compare favorably with respect to optical detection.The nitrogen vacancy center NV -in diamond is a promising candidate for quantum applications, since its coherence time at room temperature is in the range of ms [1] and its spin can be read out by optical fluorescence detection [2]. These features have enabled the use of NV -centers, e.g., as a quantum sensor for magnetic fields [3,4] and temperature [5] , for scanning-probe spin imaging [6] and structure determination of single biological molecules [7]. Despite its apparent simplicity, however, optical spin readout has drawbacks: it is highly inefficient, requiring several 100 repetitions for a single spin readout, and cumbersome to implement in many applications. Electric readout of spin in a suitable diamond semiconductor device appears as an attractive way to surmount these limitations. It could enable access to NV -centers in dense arrays, with a spacing limited by the few-nm-small feature size of electron beam lithography [8] rather than the optical wavelength. It might, moreover, provide a way to read out other spin defects [9-11], potentially including optically inactive ones.Two methods for electric readout of NV -centers have been demonstrated. The method in Ref. 12 uses nonradiative energy transfer to graphene and detects the spin signal in the current through the graphene sheet generated by this transfer. In contrast, the method presented in Ref. 13 uses the charge carriers generated directly in the diamond host crystal by photoionization of the NV -centers (photocurrent detection of magnetic resonance, PDMR). Both methods, however, have until now only been used with continuous wave (cw) spin manipulation and have therefore remained limited to NV -detection. Here we demonstrate a scheme based on both pulsed spin manipulation and pulsed photoionization to truely read out the spin state of NV -centers electrically after coherent control, using Rabi oscillations and echo experiments as examples. We employ this scheme to establish a quantitative model of photoionization, simulate the readout efficiency and predict, that under optimized conditions pulsed electric readout could outperform optical fluorescence detection.The spin-dependent photoionization cycle can be understood as an effective four-photon process, whose spin dependence relies on the NV -center's inter-system crossing (ISC) which is also key to the classic optical readout ( Fig. 1 a)) [13]. A first photon (green arrows) triggers shelving (black arrow) of NV -centers in spin state |2 (corresponding to the m S = ±1 spin quantum numbers of NV -) into the long-lived metastable singlet state |5 by this ISC. Si...

Spin Readout Techniques of the Nitrogen-Vacancy Center in Diamond

“…Initial experiments demonstrated electrical detection of continuous-wave electron spin resonance for ensembles of NV centers [ 129 , 130 ]. Recent advances in device design, lock-in detection, pulsed measurements, and multi-color pump beams have lead to improved contrast [ 131 , 132 ] and a current detection limit of only five NV centers [ 133 ].…”

Negative charge enhancement of near-surface nitrogen vacancy centers by multicolor excitation

“…We neglect possible contributions of two-photon processes originating from the ground-state to these dynamics, as suggested in Ref. [20] (see also [23,27]). The internal NV − /NV 0 transition rates considered in this model were taken from Ref.…”

Enhanced photoelectric detection of NV magnetic resonances in diamond under dual-beam excitation

“…1). The compatibility of this readout method with coherent manipulations of NV spin ensembles was recently reported [12]. Enhancing the photocurrent signal and MR contrast is critical to reach a high sensitivity of magnetic resonance (MR) detection [4,13] To explore the photophysics behind the PDMR scheme and optimize its performances, we performed ab initio calculations of N 0 s , NV -, and NV 0 ionization cross sections, and compared the results to experimental characterizations of the ionization bands.…”