The color centers in diamonds are promising candidates in the context of quantum information science, quantum computation, and spin-based quantum sensors due to their exceptional spin-dependent emission properties. The manipulation and the optical readout of the spin state is measured using a spectroscopic technique known as the Optically Detected Magnetic Resonance (ODMR). Here, we discuss the indigenous development of an ODMR setup to manipulate and measure the spin state of nitrogen-vacancy centers in diamond. The study involves the confocal mapping of NV centers to measure the spin state by applying a micro-wave field. The spin state control appears as a dip in the measured emission intensity as a function of micro-wave frequency.
The color centers in diamonds are promising candidates in the context of quantum information science, quantum computation, and spin-based quantum sensors due to their exceptional spin-dependent emission properties. The manipulation and the optical readout of the spin state is measured using a spectroscopic technique known as the Optically Detected Magnetic Resonance (ODMR). Here, we discuss the indigenous development of an ODMR setup to manipulate and measure the spin state of nitrogen-vacancy centers in diamond. The study involves the confocal mapping of NV centers to measure the spin state by applying a micro-wave field. The spin state control appears as a dip in the measured emission intensity as a function of micro-wave frequency.
The ability to measure and manipulate the quantum state of a single spin in a solid state system opens up a broad range of powerful applications ranging from nano probes to quantum information processing. Over the past few years, a number of ground breaking experiments have been conducted on paramagnetic nitrogen vacancy defect centers in diamond, including up to 3-qubit entanglement, single-shot-readout of a nuclear spin, selective access of two coupled centers and magnetic, electric and thermographic sensing at the nanoscale with promising properties in some cases exceeding most currently known techniques. Yet, almost all of the experiments conducted so far focus on centers deeply buried in the diamond, which is undesirable especially for sensing applications, but also in terms of scalability and electronic access to the information. In this work we focus on the spin physics of centers only few nanometers below the surface, where the unique properties of the center are strongly influenced by the external environment. We coherently manipulated and detected single spins at ambient temperature by combining optically detected magnetic resonance with single molecule spectroscopy using a confocal microscope. We measured the spin dephasing behavior and the phase relaxation time and examined the primary sources of decoherence. Furthermore, we observed effects of water, atmosphere and paramagnetic molecules on the coherence and readability of spins in nanodiamonds and demonstrated ways to preserve the coherence using external magnetic fields and a number of different dynamic decoupling pulse sequences. In addition, we measured couplings to proximal nuclear spins by continuous wave spectroscopy and to molecules on the surface by double electron electron resonance. Also, we demonstrate execution of the refined Deutsch-Jozsa algorithm on a nitrogen vacancy center in a nanodiamond. Finally, we propose new technological approach for realtime measurements of magnetic fields using a single spin in diamond. In test measurements using external fields and spatially resolved measurements of the field from a magnetic microwire a sensitivity of a few uT / sqrt(Hz) was achieved.
Atomic scale defects in diamond are emerging as next-generation quantum sensors. One such defect is the nitrogen vacancy (NV) center which possesses artificial atom-like properties making it a strong contender for a room temperature solid state qubit. These spin defects are optically addressable by studying their optically detected magnetic resonance spectra (ODMR). The spin states can be initialized, controlled, and read out by a shining laser. The photoluminescence spectra contain information on the external magnetic field, electric field, temperature, etc. Thus, this type of multimodal sensor is exigent in various fields of research viz. chemistry, materials science, biology, and fundamental physics. In today's world where energy-related products are booming, deployment of quantum sensors can expedite the development. Based on existing works, this paper makes an attempt to identify the applications of color centers in diamond for energy sectors. We have highlighted the efficacy of quantum diamond sensors in the oil and gas industry, battery research, and photovoltaics. In addition, a summary of the structural and quantum properties of defects in diamond, synthesis of diamond, protocols for optical detection of spin states, different types of color centers, etc., is presented.
We demonstrate the use of two-photon excitation for observing the ground state optically detected magnetic resonance (ODMR) of nitrogen-vacancy centers in diamonds at room temperature. An ultrafast femtosecond laser at 1040 nm was used for excitation, while fluorescence signal read out was achieved through a combination of a PMT and a lock-in amplifier. The imaging capability of two-photon excitation fluorescence (2PEF) was utilized to map the distribution of NV centers in a bulk diamond and micro-sized diamonds. For the first time, ODMR traces of the nitrogen-vacancy center are observed with two-photon excitation, providing a promising tool for fast 3D quantum sensing and imaging.
We demonstrate the use of two-photon excitation for observing the ground-state optically detected magnetic resonance (ODMR) of nitrogen-vacancy centers in diamonds at room temperature. An ultrafast femtosecond laser at 1040 nm was used for excitation, while fluorescence signal readout was achieved through a combination of a PMT and a lock-in amplifier. The imaging capability of two-photon excitation fluorescence (2PEF) was utilized to map the relative distribution of NV centers in a bulk diamond and micro-sized diamonds. For the first time, to the best of our knowledge, ODMR traces of the nitrogen-vacancy center are observed with two-photon excitation, providing a promising tool for fast 3D quantum sensing and imaging.
Nitrogen-vacancy (NV) centers in diamond are a leading platform for solid-state quantum sensing and quantum information processing. While most optical studies rely on the visible fluorescence associated with the triplet transitions, the infrared singlet transition near 1042 nm, which is typically considered dark within the singlet manifold of the NV optical cycle, provides an alternative optical channel. Here, we report wavelength-resolved optically detected magnetic resonance (ODMR) measurements of this infrared emission. We directly observe ODMR contrast in the 1042 nm emission and analyze its dependence on the magnetic field. The field-dependent spectral dispersion of the ODMR signal demonstrates that the spin-state information encoded in the NV center is transcribed to the infrared singlet emission through the spin-selective intersystem crossing, in close analogy to the visible fluorescence readout. These results establish infrared ODMR as a high-fidelity optical readout pathway. Crucially, by extending spin-state transcription directly into the 1300−1600 nm range, this work demonstrates a direct, conversion-free interface between diamond spin-qubits and standard telecommunication infrastructure, bypassing the efficiency bottlenecks of active frequency conversion and benefiting from the already well-developed technologies in this range of the electromagnetic spectrum.
Abstract A novel method for reading out the electron spin state of the negatively charged nitrogen‐vacancy (NV) point defect in diamond, based on photoelectric detection of NV magnetic resonances (PDMR), is reviewed. As a convenient way to measure the spin state of qubits, the presented technique is anticipated to lead to a vast range of applications in the field of quantum technologies. It has been demonstrated that this method can be used both in continuous‐wave mode and for the pulse readout of coherently manipulated NV− spins. The PDMR technique presents interesting advantages over the commonly used optical detection of magnetic resonances (ODMR) and was recently downscaled to the reading out of a single NV− spin qubit. The principles, current developments, advantages, and drawbacks of PDMR are presented in this progress report. A complete to‐date methodology of NV photoelectric readout is described and PDMR is compared to ODMR. Future developments and possible improvements of the technique are mentioned. The results of the latest studies, aiming at overcoming limitations in the PDMR contrast through a better understanding of NV photo‐physics and of charge exchanges between NV centers and other electrically active defects, are discussed.