arXiv subjects

Emilie Bourgeois

Publications and source records attributed to Emilie Bourgeois.

7 recordsLinked to original sources

arXiv2026

Irradiation-Induced Spin Bath Evolution and as-Grown Hydrogen Defects in CVD Diamond Revealed by NV-Based DEER Spectroscopy

The aim of this paper is to provide the reader with a review and current state of the art of the fabrication of high T2 coherence diamond, optimised by the use of double electron-electron resonance (DEER) spectroscopy. Using DEER, we study the formation, transformation, and annealing of paramagnetic defects in as-grown CVD diamond and after post-processing. Electron irradiation leads to the formation of an additional S = 1/2 resonance in the DEER spectrum, which we consider to be a composite X ensemble. By tracking the concentrations of X and P1 point defects during annealing from 650C to 1200C, we find that the X ensemble initially consists of a mixture of V- spins and interstitial spins, which disappear at about 650C. Vacancies migrate during annealing, forming clusters that persist to 1000C and disappear upon annealing at 1200C, contributing to the X ensemble signal. We have developed a model of the influence of the mixed spin bath on the coherence of NV centers, which includes independent couplings with P1 centers, V-, divacancies, and interstitials. Detailed DEER studies allowed us to reveal and resolve a weak signal from two additional S = 1/2 species associated with hydrogen: NVH- and consistent with a substitutional hydrogen defect, which overlaps the vacancy spectral line. Taken together, these results show that the NV-DEER method is a powerful tool for investigating paramagnetic defects in diamond with high precision and nanoscale resolution, essential for material optimisation. The achieved high T2 coherence time is consistent with the spin bath model, and the crystals reach the quality required for advanced quantum sensing applications.

quant-ph↗

arXiv2026

High PDMR contrast in single NV centres and related photocurrent properties

This paper aims to extend the understanding of the mechanism of photo-electrical detection of magnetic resonance (PDMR) in nitrogen-vacancy (NV) centres. This technique is particularly important for development of solid-state quantum computing platforms. In particular, we report on the new insight in the photocurrent (PC) generation and charge cycling in the single NV centre, which is related to PDMR contrast reaching 50\% and above. We develop a technique to locate PC related features. We find that electrons generated at the NV centre are stored in interface trap levels and establish that the interface states serve as an amplifier that can be driven by introducing a second laser into our confocal setup. We show that controlling these interface states allows one to significantly enhance the PDMR contrast. We develop a model that consistently explains observed amplification effects even without the application of a bias voltage.

quant-ph↗

arXiv2025

Modelling and experimental verification of photoelectrical response of NV diamond spin centres

We report on a mathematical model of the photoelectric response of NV colour centres in diamond, that can be employed for sensing and quantum science information applications. Although the model applies to NV centre in diamond, it can be applied with small modifications to other semiconducting solid state qubits. In our model, we include the drift and collection of charge carriers as well as the presence of other defects via generation and recombination dynamics. Though the photoluminescence readout and the associated dynamics of the NV defect has been extensively studied experimentally and theoretically, so far, there has been no precise model for photocurrent readout, including these effects. In our description, we use a multilevel-level system including mS=0, mS=+-1 ground and excited states, singlet state and the NV0 neutral state. Also, the presence of substitutional nitrogen (NS), which for example determines the spin coherence via the paramagnetic spin bath, is discussed together with presence of acceptor defects. We model the time-dependent occupation of all electronic sublevels and also consider the electronic charge transport from the Boltzmann transport equation, leading to information about the charge state transitions and recombination dynamics. ODMR and PDMR response as well as their quantum efficiencies, are calculated. On this basis, we determine an optimal parameter space for qubit operations, including the highest spin contrast and especially relate those to NS presence. The model is confirmed experimentally and can become a useful tool for optimisation of the performance of NV qubit photoelectric readout.

quant-ph↗

arXiv2025

Electrical Readout of Spin Environments in Diamond for Quantum Sensing

Nitrogen-vacancy (NV) centres in diamond are a key platform for quantum sensing and quantum information, combining long coherence times with controllable spin-spin interactions. Most of current quantum algorithms rely on optical access, which limit device integration and applicability in opaque or miniaturized settings. Here we demonstrate an all-electrical approach, photocurrent double electron-electron resonance (PC-DEER), permitting exploiting local dipolar interactions between individual NV spin qubits or ensembles and nearby paramagnetic defects with sub-confocal resolution. PC-DEER extends photocurrent NV readout from single-spin to spin-bath control and coherent manipulation, enabling characterization of bath-induced noise and effective deployment of noise-reduction protocols. We resolve the signatures of substitutional nitrogen (P1) and NVH centers with reproducible contrast by using electrical signals. Our results establish a scalable, optical-free spin readout strategy that bridges fundamental studies of spin environments with deployable quantum technologies, advancing the integration of diamond-based sensors into solid-state quantum devices.

quant-ph↗

arXiv2022

Electrical readout microwave-free sensing with diamond

While nitrogen-vacancy (NV-) centers have been extensively investigated in the context of spin-based quantum technologies, the spin-state readout is conventionally performed optically, which may limit miniaturization and scalability. Here, we report photoelectric readout of ground-state cross-relaxation features, which serves as a method for measuring electron spin resonance spectra of nanoscale electronic environments and also for microwave-free sensing. As a proof of concept, by systematically tuning NV centers into resonance with the target electronic system, we extracted the spectra for the P1 electronic spin bath in diamond. Such detection may enable probing optically inactive defects and the dynamics of local spin environment. We also demonstrate a magnetometer based on photoelectric detection of the ground-state level anticrossings (GSLAC), which exhibits a favorable detection efficiency as well as magnetic sensitivity. This approach may offer potential solutions for determining spin densities and characterizing local environment.

physics.app-ph↗

arXiv2021

Room-temperature control and electrical readout of individual nitrogen-vacancy nuclear spins

Nuclear spins in semiconductors are leading candidates for quantum technologies, including quantum computation, communication, and sensing. Nuclear spins in diamond are particularly attractive due to their extremely long coherence lifetime. With the nitrogen-vacancy (NV) centre, such nuclear qubits benefit from an auxiliary electronic qubit, which has enabled entanglement mediated by photonic links. The transport of quantum information by the electron itself, via controlled transfer to an adjacent centre or via the dipolar interaction, would enable even faster and smaller processors, but optical readout of arrays of such nodes presents daunting challenges due to the required sub-diffraction inter-site distances. Here, we demonstrate the electrical readout of a basic unit of such systems - a single 14N nuclear spin coupled to the NV electron. Our results provide the key ingredients for quantum gate operations and electrical readout of nuclear qubit registers, in a manner compatible with nanoscale electrode structures. This demonstration is therefore a milestone towards large-scale diamond quantum devices with semiconductor scalability.

cond-mat.mes-hall↗

arXiv2016

Pulsed photoelectric coherent manipulation and detection of NV centre spins in diamond

Hybrid photoelectric detection of NV magnetic resonances (PDMR) is anticipated to lead to scalable quantum chip technology. To achieve this goal, it is crucial to prove that PDMR readout is compatible with the coherent spin control. Here we present PDMR MW pulse protocols that filter background currents related to ionization of NS0 defects and achieve a high contrast and S/N ratio. We demonstrate Rabi and Ramsey protocols on shallow nitrogen-implanted electronic grade diamond and the coherent readout of ~ 5 NV spins, as a first step towards the fabrication of scalable photoelectric quantum devices.

cond-mat.mes-hall↗