Diamond NV Research Articles

Qubit teleportation between a memory-compatible photonic time-bin qubit and a solid-state quantum network node

We report on a quantum interface linking a diamond NV center quantum network node and 795nm photonic time-bin qubits compatible with Thulium and Rubidium quantum memories. The interface makes use of two-stage low-noise quantum frequency conversion and waveform shaping to match temporal and spectral photon profiles. Two-photon quantum interference shows high indistinguishability between converted 795nm photons and the native NV center photons. We use the interface to demonstrate quantum teleportation including real-time feedforward from an unbiased set of 795nm photonic qubit input states to the NV center spin qubit, achieving a teleportation fidelity well above the classical bound. This proof-of-concept experiment shows the feasibility of interconnecting different quantum network hardware.

An Integrated Noncontact Torque Sensor Based on Diamond NV Centers

An Integrated Noncontact Torque Sensor Based on Diamond NV Centers

Exploration of a high-precision measurement scheme for current sensors based on diamond NV color centers

A high-precision measurement scheme for current sensors based on diamond NV color centers was verified. In the research process, diamond crystals containing a large number of NV color centers are applied as the probe of the sensor, and the magnetic field generated by the current is measured to explore the relationship between the current intensity and the fluorescence intensity of the NV color centers and the polarization resonance, to carry out simulation experiments, and finally to obtain the results of the effect of the concentration of the NV color centers on the performance of the sensor. The results of simulation experiments show that the accuracy of the current measurement is within 100-500 A, and the result is 0.3%. By applying NV color centers to current measurement, good results have been obtained in terms of accuracy and frequency response range, enabling high-precision current measurement as well as providing monitoring and analysis of high-frequency current inrush.

A Portable and Highly Integrated Solid-State Quantum Magnetometer Module Based on the Diamond NV Color Centers

A Portable and Highly Integrated Solid-State Quantum Magnetometer Module Based on the Diamond NV Color Centers

Enhancing fluorescence of diamond NV− centers for quantum sensing: A multi-layer optical antireflection coating

The negatively charged nitrogen-vacancy centers (NV− centers) in diamonds possess outstanding magneto-optical properties and have broad applications in cutting-edge fields, such as quantum sensing, quantum communication, and quantum computing. However, the reflection loss around the wavelength of NV− photoluminescence (PL) spectrum caused by the diamond–air interface is still a drawback. In this work, a multi-layer optical antireflection coating was designed via genetic algorithms to resolve this problem. The simulation results show that coating can increase the average transmissivity from 82.90 % to 99.84 %. We coated the diamond sample with eight SiO2 and Ta2O5 overlapping layers based on the simulation results. After depositing the coating, the transmissivity increased from 83.84 % to 98.10 %, corresponding to a 17.01 % improvement. Furthermore, the intensity of the PL spectrum increased by a factor of 1.26, confirming the superior properties of the diamond–air interface with the coating. Finally, an NV-based magnetometer was constructed to prove the application significance of our coating. It was found that the sensitivity increased from 57.19 to 25.53 nT∙Hz−1/2. This scheme demonstrates the positive effect of coating in improving the system's comprehensive performance, especially signal-to-noise ratio, but also benefits the miniaturization and integration of diamond magnetometers, which will contribute to achieving related quantum information processing based on defective diamonds.

A Portable Application Type Magnetometer Based on Diamond NV Centers

A Portable Application Type Magnetometer Based on Diamond NV Centers

A low complexity reconstruction approach for optical detection magnetic resonance based diamond NV color center magnetic field measurement

A low complexity reconstruction approach for optical detection magnetic resonance based diamond NV color center magnetic field measurement

Compact and portable quantum sensor module using diamond NV centers

We developed a compact and portable measuring instrument using diamond NV centers that operates on the USB 3.0 power supply of a laptop computer. Its portability is achieved by the low power consumption of the optics, realized by the diamond corner cube that enhanced the current of the photodiode to 2.1 times higher than that of the planar diamond, and that of the microwave source, reduced by 20 dB, which was realized by a microwave resonator using a λ/4 open stub that strongly magnetically drives the NV center. These results contribute to the social implementation of diamond sensors.

Proposal to detect emergent gauge field and its Meissner effect in spin liquids using NV centers

We show that NV centers could provide distinct signatures of emergent gauge fields in certain phase transitions in spin liquids. We consider the relaxation rate $1/T_1$ of a diamond NV center placed a distance $z_0$ above a crystal consisting of two dimensional layers which hosts a $U(1)$ quantum spin liquid with spinon Fermi surface. We show that during a spinon pairing transition from a $U(1)$ to a $\mathbb{Z}_2$ spin liquid, the relaxation rate exhibits a rapid fall just below the pairing transition. The drop is much faster than what can be accounted for by the opening of the energy gap. Instead, the rapid fall with a unique $z_0$ dependence of its height and width, is the signature of the Meissner effect of the gauge field. We identify the organic ET compound which has a phase transition at 6K as a candidate for the experimental observation of this phenomenon.

NV-centers in SiC: A solution for quantum computing technology?

Spin S = 1 centers in diamond and recently in silicon carbide, have been identified as interesting solid-state qubits for various quantum technologies. The largely-studied case of the nitrogen vacancy center (NV) in diamond is considered as a suitable qubit for most applications, but it is also known to have important drawbacks. More recently it has been shown that divacancies (VSiVC)° and NV (VSiNC)- centers in SiC can overcome many of these drawbacks such as compatibility with microelectronics technology, nanostructuring and n- and p-type doping. In particular, the 4H-SiC polytype is a widely used microelectronic semiconductor for power devices for which these issues are resolved and large-scale substrates (300mmm) are commercially available. The less studied 3C polytype, which can host the same centers (VV, NV), has an additional advantage, as it can be epitaxied on Si, which allows integration with Si technology. The spectral range in which optical manipulation and detection of the spin states are performed, is shifted from the visible, 632 nm for NV centers in diamond, to the near infrared 1200–1300 nm (telecom wavelength) for divacancies and NV centers in SiC. However, there are other crucial parameters for reliable information processing such as the spin-coherence times, deterministic placement on a chip and controlled defect concentrations. In this review, we revisit and compare some of the basic properties of NV centers in diamond and divacancies and NV centers in 4H and 3C-SiC.

Triply-resonant sum frequency conversion with gallium phosphide ring resonators.

We demonstrate quasi-phase matched, triply-resonant sum frequency conversion in 10.6-µm-diameter integrated gallium phosphide ring resonators. A small-signal, waveguide-to-waveguide power conversion efficiency of 8 ± 1.1%/mW; is measured for conversion from telecom (1536 nm) and near infrared (1117 nm) to visible (647 nm) wavelengths with an absolute power conversion efficiency of 6.3 ± 0.6%; measured at saturation pump power. For the complementary difference frequency generation process, a single photon conversion efficiency of 7.2%/mW from visible to telecom is projected for resonators with optimized coupling. Efficient conversion from visible to telecom will facilitate long-distance transmission of spin-entangled photons from solid-state emitters such as the diamond NV center, allowing long-distance entanglement for quantum networks.

SNR enhancement of magnetic fields measurement with the diamond NV center using a compound filter system

SNR enhancement of magnetic fields measurement with the diamond NV center using a compound filter system

Surface H‐field mapping of a GaAs single pole double throw switch chip based on quantum diamond probe

With the improvement of design capability and manufacture technology, the integration as well as the complexity of chips have also increased dramatically, and it becomes critical to realize noninvasive electromagnetic inspection of chips at higher resolutions. In this paper, we propose a submicron-resolution microwave near-field imaging system based on the nitrogen-vacancy center (NV) in diamond, which mainly consists of an optical hardware system and a software control system, and can be used for nondestructive imaging of microwave fields on the surface of integrated circuits with submicron resolution. We applied this technique to scan the surface microwave field distribution of a GaAs single pole double throw switch chip. The scanning imaging system can image the near-field magnetic distribution for the chip, which provides a new solution for analyzing the current distribution on the chip surface and thus addressing problems such as excessive current or crosstalk. It is worth mentioning that the diamond NV color center-based sensor has a very high-spatial resolution and magnetic field detection sensitivity at room temperature, while the dielectric constant of natural diamond is 5.5, which also provides the possibility of diamond as a sensor in complex radiation environments and is an ideal detector material for near-field imaging of electromagnetic fields.

Quasiparticle energies and optical excitations of 3C-SiC divacancy from GW and GW plus Bethe-Salpeter equation calculations

The authors study the divacancy in 3C-SiC, a promising system for quantum information or sensing applications, using large-scale GW plus Bethe-Salpeter equation simulations of nearly 1000 atoms. Notably, in contrast to the widely studied diamond NV center, low-energy excitonic states of 3C-SiC divacancy show substantial characters of transitions from localized defect states to continuum states. Some defect states that contribute to the low-energy excitations significantly hybridize with conduction bands. This work quantitatively determines the quasiparticle energies of defect states and zero-phonon line energy, emphasizing the importance of frontier conduction bands on the low-energy excitons of 3C-SiC divacancy.

Directional luminescence of the diamond NV center via Bloch surface waves in one-dimensional photonic crystals

In this work, we numerically study the luminescence of nanodiamonds with NV centres embedded in a polymer layer on the surface of one-dimensional photonic crystal. The interaction of NV center spontaneous emission with the Bloch surface wave (BSW) is demonstrated. The presence of a photonic crystal leads to a change in the angular distribution of the emitter radiation due to the coupling of luminescence to BSW. We show that the best coupling efficiency of 71% is observed when NV centres are located in the close proximity to the BSW field maximum.

Si nanopillar arrays as possible electronic device platforms

This paper explores the possible use of silicon nanopillars as electronic devices. The silicon nanopillars studied in this work were fabricated by electron beam lithography and by plasma ion etching of silicon wafers. The electrical and physical properties of these pillars with full width at half maximum ranging from few nanometers to 100 nm and length of few hundreds of nanometer have been investigated by time-resolwed photoluminescence, infrared spectroscopy and current-voltage characteristics. An ultrafast blue luminescence component competing with non-radiative recombination at surface defects was quantified as originating from the no-phonon recombination. This component involved two decay processes with a peak energy at around 500 nm, which have the fast component close to femtosecond time scale. The emission exhibits also a slow component in the red spectral region with a time constant in the nanosecond regime. The nanopillars have been smoothened in an attempt to passivate surface defects. The results are indicative of an increase in the lifetimes-of carriers and an enhancement in the red component of the emission with much slower sates. The presence of ultrafast decay at blue-green spectral region is suggestive of the possibility of using the silicon nanopillars as ultrafast switching devices. Silicon nanopillar arrays can also be an ideal platform in trapping and sensing chemical or biological species using diamond NV centers.

Preferential coupling of diamond NV centres in step-index fibres.

Diamonds containing the negatively charged nitrogen-vacancy centre are a promising system for room-temperature magnetometry. The combination of nano- and micro-diamond particles with optical fibres provides an option for deploying nitrogen-vacancy magnetometers in harsh and challenging environments. Here we numerically explore the coupling efficiency from nitrogen-vacancy centres within a diamond doped at the core/clad interface across a range of commercially available fibre types so as to inform the design process for a diamond in fibre magnetometers. We determine coupling efficiencies from nitrogen-vacancy centres to the guided modes of a step-index fibre and predict the optically detected magnetic resonance (ODMR) generated by a ensemble of four nitrogen-vacancy centres in this hybrid fibre system. Our results show that the coupling efficiency is enhanced with a high refractive index difference between the fibre core and cladding and depends on the radial position of the nitrogen-vacancy centres in the fibre core. Our ODMR simulations show that due to the preferential coupling of the nitrogen-vacancy emission to the fibre guided modes, certain magnetometry features such as ODMR contrast can be enhanced and lead to improved sensitivity in such diamond-fibre systems, relative to conventional diamond only ensemble geometries.

Several Ways to Implement Qubits in Physics

In order to achieve quantum computation, the qubit preparation is crucial, given that the performance relies on various gate operations, which is determined by the quality of qubit. This paper introduces many qubits, including atoms (neutral atoms and ions) and spins (quantum dots, diamond NV centers, and nuclear magnetic resonance) that depend on various systems. Moreover, they are mentioned separately in this paper due to the significance of superconducting qubits. Meanwhile, the advantages and drawbacks of these qubits are compared, e.g. their coherence (long coherence time between neutral atoms and ions), operating temperature, quantum state reading, quantum system ease of handling, and precision of handling. Challenges as well as corresponding resolved methods have been addressed and reviewed. Current gaps and limitations are also discussed.

Coherent Population Oscillation of Magnetometer Based on Diamond NV Color Center Ensemble

Coherent Population Oscillation of Magnetometer Based on Diamond NV Color Center Ensemble

Integrated microwave cavity and antenna to improve the sensitivity of diamond NV center spin-based sensors

A microwave (MW)-cavity antenna was designed to manipulate the spin state in diamond. It consists of an Ω antenna and a MW cavity with a thickness of 0.35 mm and a Q-value of 65. The MW intensity increased 12 times compared to that of the Ω antenna. The size of the homogeneity area is and the heterogeneity is less than 2.3%. Hence, more spin structures in large-sized diamonds with a high concentration can be homogeneously excited. As applied in the spin-based magnetometer, the sensitivity increased 13 times, and the noise reduced to It paves the way for the development of highly sensitive spin-based sensors.