Interplay between dressed and strong-axial-field states in nitrogen vacancy centers for quantum sensing and computation G. Zanelli, E. Moreva, E. Bernardi, E. Losero, S. Ditalia Tchernij, et al. Physical Review B, 2025 The nitrogen vacancy (NV) center in diamond is an intriguing electronic spin system with applications in quantum radiometry, sensing, and computation. In those experiments, a bias magnetic field is commonly applied along the NV symmetry axis to eliminate the triplet ground-state manifold's degeneracy ( S = 1 ). In this configuration, the eigenvectors of the NV spin's projection along its axis are called strong-axial-field states. Conversely, in some experiments, a weak magnetic field is applied orthogonally to the NV symmetry axis, leading to eigenstates that are balanced linear superpositions of strong-axial-field states, referred to as dressed states. The latter are sensitive to environmental magnetic noise at the second order, allowing to perform magnetic field protected measurements while providing increased coherence times. However, if a small axial magnetic field is added in this regime, the linear superposition of strong-axial-field states becomes unbalanced. This paper presents a comprehensive study of free induction decay (FID) measurements performed on an NV center ensemble in the presence of strain and weak orthogonal magnetic field, as a function of a small magnetic field applied along the NV symmetry axis. The simultaneous detection of dressed states and unbalanced superpositions of strong-axial-field states in a single FID measurement is shown, gaining insight into coherence time, nuclear spin, and the interplay between temperature and magnetic field sensitivity. The discussion concludes by describing how the simultaneous presence of magnetically sensitive and insensitive states opens up appealing possibilities for both sensing and quantum computation applications.
Effects of Thermal Oxidation and Proton Irradiation on Optically Detected Magnetic Resonance Sensitivity in Sub-100 nm Nanodiamonds Pietro Aprà, Gabriele Zanelli, Elena Losero, Nour-Hanne Amine, Greta Andrini, et al. ACS Applied Materials and Interfaces, 2025 In recent decades, nanodiamonds (NDs) have emerged as innovative nanotools for weak magnetic fields and small temperature variation sensing, especially in biological systems. At the basis of the use of NDs as quantum sensors are nitrogen-vacancy center lattice defects, whose electronic structures are influenced by the surrounding environment and can be probed by the optically detected magnetic resonance technique. Ideally, limiting the NDs' size as much as possible is important to ensure higher biocompatibility and provide higher spatial resolution. However, size reduction typically worsens the NDs' sensing properties. This study endeavors to obtain sub-100 nm NDs suitable to be used as quantum sensors. Thermal processing and surface oxidations were performed to purify NDs and control their surface chemistry and size. Ion irradiation techniques were also employed to increase the concentration of the nitrogen-vacancy centers. The impact of these processes was explored in terms of surface chemistry (diffuse reflectance infrared Fourier transform spectroscopy), structural and optical properties (Raman and photoluminescence spectroscopy), dimension variation (atomic force microscopy measurements), and optically detected magnetic resonance temperature sensitivity. Our results demonstrate how surface optimization and defect density enhancement can reduce the detrimental impact of size reduction, opening to the possibility of minimally invasive high-performance sensing of physical quantities in biological environments with nanoscale spatial resolution.
Quantum photonics sensing in biosystems Ekaterina Moreva, Valeria Cimini, Ilaria Gianani, Ettore Bernardi, Paolo Traina, et al. APL Photonics, 2025 Quantum sensors emerged among quantum technologies as the ones with promising potential applications in the near future. This perspective reviews two leading quantum sensing platforms and their advancements toward biological applications: quantum light sources and color centers in diamonds. Quantum light, including squeezed states and N00N states, allows enhanced phase measurements by surpassing the classical shot noise limits. This advantage can be exploited in several contexts, enabling improved resolution and sensitivity, which are particularly valuable in biological contexts where traditional high-intensity illumination could damage or alter delicate samples. In parallel, color centers in diamonds, specifically nitrogen-vacancy and silicon-vacancy centers, also emerged as promising for sensing applications due to their high sensitivity and biocompatibility. These sensors enable detailed intracellular measurements, such as temperature detection, and show potential for measuring magnetic fields of biological origin. Despite these advancements, significant challenges remain in translating these technologies from a controlled laboratory environment to practical, widely applicable devices for diverse biological applications. Overcoming these challenges is crucial for unlocking the full potential of quantum sensors in the biological field.
Enhanced Temperature Sensing with Nitrogen-Vacancy Spin Ensembles in Diamond E Moreva, E Bernardi, G Zanelli, P Traina, V Pugliese, et al. Journal of Physics Conference Series, 2025 We present advancements in an enhanced temperature measurement technique using NV centers in diamond with an orthogonal orientation of bias magnetic file. This approach reduces magnetic noise interference and improves sensitivity, particularly in biocompatible conditions. We systematically evaluate the sensitivity of the diamond-based temperature sensor and demonstrate up one order improved sensitivity at low laser power for the “super transverse” bias magnetic field (S-TBMF) regime. This approach simplifies the experimental setup, provides remarkable magnetic noise decoupling, and can be extended to temperature sensing using nanodiamonds (NDs).
Activation of telecom emitters in silicon upon ion implantation and ns pulsed laser annealing Greta Andrini, Gabriele Zanelli, Sviatoslav Ditalia Tchernij, Emilio Corte, Elena Nieto Hernández, et al. Communications Materials, 2024 Recent demonstrations of optically active telecom emitters show that silicon is a compelling candidate for solid-state quantum photonic platforms. In particular, the fabrication of a defect known as the G center has been shown in carbon-rich silicon upon conventional thermal annealing. However, the high-yield controlled fabrication of these emitters at the wafer scale still requires the identification of a suitable thermodynamic pathway enabling its activation following ion implantation. Here we demonstrate the activation of G centers in high-purity silicon substrates upon nanosecond pulsed laser annealing. The proposed method enables non-invasive, localized activation of G centers by the supply of short non-stationary pulses, thus overcoming the limitations of conventional rapid thermal annealing related to the structural metastability of the emitters. A finite-element analysis highlights the strong non-stationarity of the technique, offering radically different defect-engineering capabilities with respect to conventional longer thermal treatments, paving the way to the direct and controlled fabrication of emitters embedded in integrated photonic circuits and waveguides.
Limitations of Bulk Diamond Sensors for Single-Cell Thermometry Andrea Alessio, Ettore Bernardi, Ekaterina Moreva, Ivo Pietro Degiovanni, Marco Genovese, et al. Sensors, 2024 The present paper reports on a Finite Element Method (FEM) analysis of the experimental situation corresponding to the measurement of the temperature variation in a single cell plated on bulk diamond by means of optical techniques. Starting from previous experimental results, we have determined—in a uniform power density approximation and under steady-state conditions—the total heat power that has to be dissipated by a single cell plated on a glassy substrate in order to induce the typical maximum temperature increase ΔTglass=1 K. While keeping all of the other parameters constant, the glassy substrate has been replaced by a diamond plate. The FEM analysis shows that, in this case, the maximum temperature increase is expected at the diamond/cell interface and is as small as ΔTdiam=4.6×10−4 K. We have also calculated the typical decay time in the transient scenario, which resulted in τ≈ 250 μs. By comparing these results with the state-of-the-art sensitivity values, we prove that the potential advantages of a longer coherence time, better spectral properties, and the use of special field alignments do not justify the use of diamond substrates in their bulk form.
Correction to: Nanodiamond–Quantum Sensors Reveal Temperature Variation Associated to Hippocampal Neurons Firing (Advanced Science, (2022), 9, 28, (2202014), 10.1002/advs.202202014) Giulia Petrini, Giulia Tomagra, Ettore Bernardi, Ekaterina Moreva, Paolo Traina, et al. Advanced Science, 2023 Adv. Sci. 2022, 9, 2202014 DOI: 10.1002/advs.202202014 In the originally published article, one affiliation for P. Cígler is missing. Please find the correct affiliations below: G. Petrini, E. Bernardi, E. Moreva, P. Traina, I. P. Degiovanni, M. Genovese Istituto Nazionale di Ricerca Metrologica Strada delle cacce 91, Torino 10135, Italy E-mail: m.genovese@inrim.it G. Petrini, F. Picollo Physics Department, University of Torino via P. Giuria 1, Torino 10125, Italy G. Petrini, G. Tomagra, A. Marcantoni, V. Carabelli Department of Drug and Science Technology, University of Torino Corso Raffaello 30, Torino 10125, Italy G. Tomagra, A. Marcantoni, V. Carabelli NIS Inter-departmental Centre via G. Quarello 15, Torino 10135, Italy F. Picollo, I. P. Degiovanni, M. Genovese Istituto Nazionale di Fisica Nucleare (INFN) Sez. Torino via P. Giuria 1, Torino 10125, Italy
Magnesium-Vacancy Optical Centers in Diamond Emilio Corte, Greta Andrini, Elena Nieto Hernández, Vanna Pugliese, Ângelo Costa, et al. ACS Photonics, 2023 We provide the first systematic characterization of the structural and photoluminescence properties of optically active defect centers fabricated upon implantation of 30-100 keV Mg+ ions in artificial diamond. The structural configurations of Mg-related defects were studied by the emission channeling technique for 27Mg implantations performed both at room-temperature and 800 °C, which allowed the identification of a major fraction of Mg atoms (~30-42%) in sites which are compatible with the split-vacancy structure of the MgV complex. A smaller fraction of Mg atoms (~13-17%) was found on substitutional sites. The photoluminescence emission was investigated both at the ensemble and individual defect level in a temperature range comprised between 5 K and 300 K, offering a detailed picture of the MgV-related emission properties and revealing the occurrence of previously unreported spectral features. The optical excitability of the MgV center was also studied as a function of the optical excitation wavelength enabling to identify the optimal conditions for photostable and intense emission. The results are discussed in the context of the preliminary experimental data and the theoretical models available in the literature, with appealing perspectives for the utilization of the tunable properties of the MgV center for quantum information processing applications. * Corresponding authors: jacopo.forneris@unito.it, uwahl@ctn.tecnico.ulisboa.pt § These authors contributed equally to the work.
High sensitivity nitrogen-vacancy-assisted magnetic/electric field sensing at INRIM 24th Imeko Tc4 International Symposium and 22nd International Workshop on ADC and DAC Modelling and Testing, 2020
