arXiv subjects

Dasika Shishir

Publications and source records attributed to Dasika Shishir.

6 recordsLinked to original sources

arXiv2024

Real-time Simultaneous Dual Sensing of Temperature and Magnetic Field using NV-based Nano-diamonds

Quantum sensors based on Nitrogen Vacancy (NV) centers in diamond are highly capable of sensing multiple physical quantities. In this study, we use amplitude-modulated lock-in detection of optically detected magnetic resonance of NV nanodiamonds (NVND) to investigate the link between temperature (T) and the zero-field splitting parameter (D) and also the relationship between magnetic field values and the difference of resonance frequencies. We also present NVNDs' capacity to simultaneously sense both thermal and magnetic fields in real time. This dual-sensing approach is beneficial for studying magnetic materials whose magnetization depends on temperature and the applied magnetic field, such as certain ferromagnetic and ferrimagnetic materials. Integrating real-time thermal and magnetic field measurements provides unique opportunities for failure analysis in the integrated circuit (IC) industry and for studying thermodynamic processes in cell physiology. The ability to concurrently monitor temperature and magnetic field variations offers a powerful toolset for advancing precision diagnostics and monitoring in these fields.

quant-ph↗

arXiv2024

Phase-Based Approaches for Rapid Construction of Magnetic Fields in NV Magnetometry

With the second quantum revolution underway, quantum-enhanced sensors are moving from laboratory demonstrations to field deployments, providing enhanced and even new capabilities. Signal processing and operational software is becoming integral parts of these emerging sensing systems to reap the benefits of this progress. This paper looks into widefield Nitrogen Vacancy Center-based magnetometry and focuses on estimating the magnetic field from the Optically Detected Magnetic Resonances (ODMR) signal, a crucial output for various applications. Mapping the shifts of ODMR signals to phase estimation, a computationally efficient approaches are proposed. Involving Fourier Transform and Filtering as pre-processing steps, the suggested approaches involve linear curve fit or complex frequency estimation based on well-known super-resolution technique Estimation of Signal Parameters via Rotational Invariant Techniques (ESPRIT). The existing methods in the quantum sensing literature take different routes based on Lorentzian fitting for determining magnetic field maps. To showcase the functionality and effectiveness of the suggested techniques, relevant results, based on experimental data are provided, which shows a significant reduction in computational time with the proposed method over existing methods

physics.ins-det↗

arXiv2024

Observation of Ultra-low AC Susceptibility in Micro-magnets Using Quantum Diamond Microscope

AC susceptometry, unlike static susceptometry, offers a deeper insight into magnetic materials. By employing AC susceptibility measurements, one can glean into crucial details regarding magnetic dynamics. Nevertheless, traditional AC susceptometers are constrained to measuring changes in magnetic moments within the range of a few nano-joules per tesla. Additionally, their spatial resolution is severely limited, confining their application to bulk samples only. In this study, we introduce the utilization of a Nitrogen Vacancy (NV) center-based quantum diamond microscope for mapping the AC susceptibility of micron-scale ferromagnetic specimens. By employing coherent pulse sequences, we extract both magnitude and the phase of the field from samples within a field of view spanning 70 micro-meters while achieving a resolution of 1 micro-meter. Furthermore, we quantify changes in dipole moment on the order of a femto-joules per tesla induced by excitations at frequencies reaching several hundred kilohertz.

quant-ph↗

arXiv2024

High dynamic-range and portable magnetometer using ensemble nitrogen-vacancy centers in diamond

Nitrogen vacancy (NV) centers in diamonds have been explored for realizing a wide range of sensing applications in the last decade due to their unique quantum properties. Here we realize a compact and portable magnetometer with an ensemble of NV centers which we call the Quantum MagPI (Quantum Magnetometer with Proportional Integral control). Including the sensor head and associated electronics, our sensor assembly can fit inside 10 cm x 10 cm x 7 cm box and control electronics in 30 cm x 25 cm x 5 cm box. We achieve a bandwidth normalized sensitivity of ~ 10 nT/sqrt(Hz). Using closed-loop feedback for locking to the resonance frequency, we extend the linear dynamic range to 200 microT (20x improvement compared to the intrinsic dynamic range) without compromising the sensitivity. We report a detailed performance analysis of the magnetometer through measurements of noise spectra, Allan deviation, and tracking of nT-level magnetic fields in real-time. Additionally, we demonstrate the utility of such a magnetometer by real-time tracking the movement of the elevator car and door opening by measuring the projection of the magnetic field along one of the NV-axes under ambient temperature and humidity.

quant-ph↗

arXiv2023

Decoupling Nuclear Spins via Interaction-Induced Freezing in Nitrogen Vacancy Centers in Diamond

Nitrogen-Vacancy (NV) centers in diamonds provide a room-temperature platform for various emerging quantum technologies, e.g. the long nuclear spin coherence times as potential quantum memory registers. We demonstrate a freezing protocol for an NV center to isolate its intrinsic nuclear spin from a noisy electromagnetic environment. Any initial state of the nuclear spin can be frozen when the hyperfine-coupled electron and nuclear spins are simultaneously driven with unequal Rabi frequencies. Through numerical simulations, we show that our protocol can effectively shield the nuclear spin from strong drive or noise fields. We also observe a clear suppression of quantum correlations in the frozen nuclear spin regime by measuring the quantum discord of the electron-nuclear spin system. These features can be instrumental in extending the storage times of NV nuclear-spin based quantum memories in hybrid quantum systems.

quant-ph↗

arXiv2022

Sub-second Temporal Magnetic Field Microscopy Using Quantum Defects in Diamond

Wide field-of-view magnetic field microscopy has been realised by probing shifts in optically detected magnetic resonance (ODMR) spectrum of Nitrogen Vacancy (NV) defect centers in diamond. However, these widefield diamond NV magnetometers require few to several minutes of acquisition to get a single magnetic field image, rendering the technique temporally static in it's current form. This limitation prevents application of diamond NV magnetometers to novel imaging of dynamically varying microscale magnetic field processes. Here, we show that the magnetic field imaging frame rate can be significantly enhanced by performing lock-in detection of NV photo-luminescence (PL), simultaneously over multiple pixels of a lock-in camera. A detailed protocol for synchronization of frequency modulated PL of NV centers with fast camera frame demodulation, at few kilohertz frequencies, has been experimentally demonstrated. This experimental technique allows magnetic field imaging of sub-second varying microscale currents in planar microcoils with imaging frame rates in the range of 50 to 200 frames per second (fps). Our work demonstrates that widefield per-pixel lock-in detection of frequency modulated NV ODMR enables dynamic magnetic field microscopy.

cond-mat.mes-hall↗