Abstract We demonstrate electrical detection of the 14 N nuclear spin coherence of NV centres at room temperature. Nuclear spins are candidates for quantum memories in quantum-information devices and quantum sensors, and hence the electrical detection of nuclear spin coherence is essential to develop and integrate such quantum devices. In the present study, we used a pulsed electrically detected electron-nuclear double resonance technique to measure the Rabi oscillations and coherence time ( T 2 ) of 14 N nuclear spins in NV centres at room temperature. We observed T 2 ≈ 0.9 ms at room temperature, however, this result should be taken as a lower limit due to limitations in the longitudinal relaxation time of the NV electron spins. Our results will pave the way for the development of novel electron- and nuclear-spin-based diamond quantum devices.
Abstract We demonstrate electrical detection of the 14 N nuclear spin coherence of NV centres at room temperature. Nuclear spins are candidates for quantum memories in quantum-information devices and quantum sensors, and hence the electrical detection of nuclear spin coherence is essential to develop and integrate such quantum devices. In the present study, we used a pulsed electrically detected electron-nuclear double resonance technique to measure the Rabi oscillations and coherence time ( T 2 ) of 14 N nuclear spins in NV centres at room temperature. We observed T 2 ≈ 0.9 ms at room temperature, however, this result should be taken as a lower limit due to limitations in the longitudinal relaxation time of the NV electron spins. Our results will pave the way for the development of novel electron- and nuclear-spin-based diamond quantum devices.
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.
NV centers ensemble have proven to be sensitive and versatile sensor platform for many applications such as magnetometry [1, 2], electric field sensing [3], thermometry [4] and rotation sensing [5]. The tradeoff between concentration of NVs and coherence lifetime of the electronic spin limits the maximum sensitivity of such devices. Recently usage of quantum memory associated with nuclear spins nearby NV center was shown to dramatically increase the sensitivity via accumulation of the sensed signal in memory [6]. This way sensing on single NV center can benefit a lot from nearby environment, but extension of this technique on atomic ensemble is still quite challenging. Here we present a versatile platform for quantum manipulation with a highly dense NV ensemble in HPHT diamond plates. In our work, we demonstrate several approaches to initialize quantum memory in regular magnetic fields, manipulation of quantum memory, and reading the quantum information from it. Also, we carefully study decoherence rate in our sample using “Echo” and “FID” techniques. We believe the key sources of decoherence in our samples are natural abundance of13C isotopes and P1 centers. To better understand and clarify contribution of each component we studied number of samples with different defect concentrations. Besides, multifrequency resonances were investigated in NV ensembles both experimentally and theoretically. Previously multifrequency resonances were studied in single NV center system at various combinations of transverse and longitudinal MW and RF field allowing to detect many-photon transitions in electron spin subshell[7]. Here we provide study of additional series of resonances achieved in NV ensemble configuration with a close look to the many-photon transitions both in electron and nuclear eigen states. This resonances could be utilized to hyperpolarize the nuclear spin environment in diamond.
Abstract Nuclear spins in semiconductors are leading candidates for future quantum technologies, including quantum computation, communication, and sensing. Nuclear spins in diamond are particularly attractive due to their long coherence time. With the nitrogen-vacancy (NV) centre, such nuclear qubits benefit from an auxiliary electronic qubit, which, at cryogenic temperatures, enables probabilistic entanglement mediated optically by photonic links. Here, we demonstrate a concept of a microelectronic quantum device at ambient conditions using diamond as wide bandgap semiconductor. The basic quantum processor unit – a single 14N nuclear spin coupled to the NV electron – is read photoelectrically and thus operates in a manner compatible with nanoscale electronics. The underlying theory provides the key ingredients for photoelectric quantum gate operations and readout of nuclear qubit registers. This demonstration is, therefore, a step towards diamond quantum devices with a readout area limited by inter-electrode distance rather than by the diffraction limit. Such scalability could enable the development of electronic quantum processors based on the dipolar interaction of spin-qubits placed at nanoscopic proximity.
Abstract Nuclear spins in semiconductors are leading candidates for future quantum technologies, including quantum computation, communication, and sensing. Nuclear spins in diamond are particularly attractive due to their long coherence time. With the nitrogen-vacancy (NV) centre, such nuclear qubits benefit from an auxiliary electronic qubit, which, at cryogenic temperatures, enables probabilistic entanglement mediated optically by photonic links. Here, we demonstrate a concept of a microelectronic quantum device at ambient conditions using diamond as wide bandgap semiconductor. The basic quantum processor unit – a single 14 N nuclear spin coupled to the NV electron – is read photoelectrically and thus operates in a manner compatible with nanoscale electronics. The underlying theory provides the key ingredients for photoelectric quantum gate operations and readout of nuclear qubit registers. This demonstration is, therefore, a step towards diamond quantum devices with a readout area limited by inter-electrode distance rather than by the diffraction limit. Such scalability could enable the development of electronic quantum processors based on the dipolar interaction of spin-qubits placed at nanoscopic proximity.
A negatively-charged nitrogen-vacancy (NV) center in diamond is a promising system for quantum computation and quantum information. It has the diamond structure with a substitutional nitrogen atom and a neighboring vacancy. An electron spin in the NV center has an exceptionally long coherence time at room temperature. Thus the NV center has a potential to realize a room-temperature quantum computer which is more efficient than a classical computer. In this dissertation, we focus on the nitrogen nuclear spin as well as the electron spin in the NV center. Every NV center has the nitrogen nuclear spin. Because of the long coherence time of the nitrogen nuclear spin, it is a good candidate for a quantum memory. Thus it is important to prepare the nitrogen nuclear spin qubit in a given pure state for quantum computation. We provide a theoretical understanding of the popular nuclear spin initialization technique. Furthermore, we propose an optimal condition for the initialization of the nitrogen nuclear spin by including the local strain in the NV center. We expect that this optimal condition can improve the purity of the nuclear spin initialization. We also propose an efficient quantum measurement protocol for the hyperfine interaction between the electron spin and the ¹⁵N nuclear spin in the NV center. A precise knowledge of the hyperfine interaction is important to reduce an error in a coherent control of the ¹⁵N nuclear spin. In this protocol, a sequence of quantum operations with successively increasing duration is utilized to estimate the hyperfine interaction with successively higher precision approaching the quantum metrology limit. Unlike common quantum metrological methods, this protocol does not need the preparation of the nuclear spin in a pure state. In the presence of realistic operation errors and electron spin decoherence, we show the overall precision of our protocol still surpasses the standard quantum limit
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.