The NV center in diamond has been attracting attention from the viewpoint of the application of ultrasensitive sensors and quantum information devices. One of the most significant properties is that the electron spin of the NV center in diamond exhibits the longest spin coherence time at room temperature among solid-state electron spin systems, which is crucial for achieving high sensitivity. This paper describes the basics of diamond-based quantum sensors and our recent research.
The NV center in diamond has been attracting attention from the viewpoint of the application of ultrasensitive sensors and quantum information devices. One of the most significant properties is that the electron spin of the NV center in diamond exhibits the longest spin coherence time at room temperature among solid-state electron spin systems, which is crucial for achieving high sensitivity. This paper describes the basics of diamond-based quantum sensors and our recent research.
Quantum sensors encompass a diverse class of devices that exploit quantum coherence to detect weak or nanoscale signals. As their behavior is tied to physical constants, quantum sensors can achieve accuracy, repeatability, and precision approaching fundamental limits [1, 2]. As a result, these sensors have shown utility in a wide range of applications in both science and engineering leading to innovations. Among many solid-state spin systems, nitrogen-vacancy (NV) centers in diamonds have attracted considerable attention as a leading platform in many fields of quantum technologies, from quantum sensing to information processing and communication applications. They have superior physical properties, and their quantum coherence is preserved even at room temperature. The energy levels of NV centers are sensitive to magnetic fields, electric fields, strain, and temperature, and the spatial resolution is scalable from nanometers to millimeters. Therefore, diamond quantum sensors are distinctive sensors with multimodality and span scalable application fields. To realize an ideal quantum sensor for applications, the technical challenges in the sensor materials and the quantum control techniques, such as coherent microwave spin manipulation, effective optical spin-state initialization, and readout, have been developed. This chapter briefly explains the sensing principle using NV centers and then introduces sensor systems for biomedical applications, and monitoring of batteries for electric vehicles and internal power devices.
One of the biggest challenges to implement quantum protocols and quantum information processing (QIP) is achieving long coherence times, usually requiring systems at ultra-low temperatures. The nitrogen-vacancy (NV) center in diamond is a promising alternative to this problem. Due to its spin properties, easy manipulation, and the possibility of doing optical state initialization and readout, it quickly became one of the best solid-state spin systems for QIP at room temperature. Here, we present the characterization of the spin-coherence of an ensemble of NV centers in an engineered sample of ultrapure diamond as a testbed for quantum protocols for quantum metrology.
In recent years, nitrogen-vacancy (NV) color centers in diamond have become excellent solid-state quantum sensors due to their electronic spin properties. Especially for their easy optical initialization and detection, together with their very large spin coherence at room temperature. Many studies have reported their use for sensing temperature, strain, electric fields, and mainly magnetic fields. Here, we show how to build a two-dimensional map of the electronic spin coherence of an ensemble of NV centers in ultra-pure diamond, using an optical imaging protocol combined with microwave pulses relying simply on a regular CCD camera.
Among the possible defects that can occur in diamonds, one that draws attention is the nitrogen-vacancy (NV) center.Studied since the early 90s, in recent years, they became one of the most promising platforms for field applications of quantum technology at room temperature, especially for quantum sensing.They are sensitive to electric and magnetic fields, temperature, and strain, making these nanosensors a versatile platform for many applications.The NV center's spin state is easy to read and manipulate by optical means, and, most interestingly, it works well at room temperature, which facilitates its use.The great challenge to implement quantum protocols and quantum algorithms is the coherence time of the quantum states.The NV center stands out for having relatively high coherence times at room temperature.This dissertation presents measurements to characterize the electron spin coherence of NV centers in an ultrapure sample of diamond designed for quantum sensing applications.These measurements combine optical e magnetic resonance techniques.For that, a method was implemented using a conventional CCD camera and a clever imaging protocol, making it possible to perform various pulsed microwave experiments on the electron spin, such as Rabi oscillations and Hahn spin-echo, which were used for determining the characteristic relaxation times (T 1 and T 2 ).Results show that this system provides at least two readily accessible qubits that can be used in quantum protocols even at room temperature.
The diamond NV center is expected to be applied to high-sensitivity quantum magnetic sensors. The excellent spin characteristics are derived from the physical properties of diamond as a high-temperature material, and it has already been reported that the spin coherence time at room temperature exceeds 2 ms. In order to improve the sensitivity, it is indispensable to improve the crystalline quality and appropriately form the NV centers. In this talk, we will focus on the research conducted at NIMS regarding diamond crystal growth for the purpose of quantum magnetic sensor application.
Among the possible defects that can occur in diamonds, one that draws attention is the nitrogen-vacancy (NV) center. Studied since the early 90s, in recent years, they became one of the most promising platforms for field applications of quantum technology at room temperature, especially for quantum sensing. They are sensitive to electric and magnetic fields, temperature, and strain, making these nanosensors a versatile platform for many applications. The NV center´s spin state is easy to read and manipulate by optical means, and, most interestingly, it works well at room temperature, which facilitates its use. The great challenge to implement quantum protocols and quantum algorithms is the coherence time of the quantum states. The NV center stands out for having relatively high coherence times at room temperature.This dissertation presents measurements to characterize the electron spin coherence of NV centers in an ultrapure sample of diamond designed for quantum sensing applications. These measurements combine optical e magnetic resonance techniques. For that, a method was implemented using a conventional CCD camera and a clever imaging protocol, making it possible to perform various pulsed microwave experiments on the electron spin, such as Rabi oscillations and Hahn spin-echo, which were used for determining the characteristic relaxation times (T1 and T2). Results show that this system provides at least two readily accessible qubits that can be used in quantum protocols even at room temperature.