A Weak Magnetic Field Sensor Based on Nitrogen-Vacancy Color Centers in a Diamond Crystal

Technical Physics - The effect of magnetically dependent absorption of radio-frequency high-frequency radiation detected by the method of optically detected magnetic resonance has been studied, and...     

Magnetic Field Mapping Around Individual Magnetic Nanoparticle Agglomerates Using Nitrogen-Vacancy Centers in Diamond

A modified diamond–photonics based metrology is proposed to explore the magnetic fields created by agglomerates of magnetic nanoparticles (MNPs). MNPs are promising for environmental and medical applications; those proposed for cancer magnetic hyperthermia treatments are small superparamagnetic <20 nm iron oxide particles. Inside cells, they assemble in larger MNP agglomerates, reaching cross-sections of several micrometers. Here, these conditions are reproduced and MNP agglomerates immobilized. Optically detected magnetic resonance (ODMR) signals recorded without a bias field in a confocal microscope and scanning across a homogenous shallow layer of fluorescent nitrogen-vacancy centers in a bulk diamond sample placed in direct contact with the MNP agglomerates are used to determine magnetic fields with a spatial resolution of 500 nm in a lateral direction. This spatial resolution allows determining magnetic field maps around individual MNP agglomerates, for which magnetic fields with strengths ranging from 0.03 mT to maximal 1.2 mT in the direct vicinity of the agglomerates and with detectable fields up to 5 µm away from the agglomerates, are determined. Based on the findings, a pathway to non-invasively study the micro/nano topology of MNP agglomerates is proposed.     

Scalable Quantum Controlled Gates on Single-Photon Polarization Qubits Assisted by Nitrogen-Vacancy Centers Inside Single-Sided Optical Cavities

International Journal of Theoretical Physics - Quantum logic gates are the foundation of circuit-based quantum computation and quantum simulation. Multi-qubit quantum controlled gates are of vital...     

表面氧化钛涂层增强金刚石中浅层NV色心的荧光强度

本文利用原子层沉积技术在金刚石表面沉积了一层氧化钛涂层,该方法使得金刚石中的浅层(深度小于10 nm)NV~-色心的电荷态变得稳定,同时其荧光强度增强至大约原本的2倍.这种表面涂层技术能够为固态量子体系提供厚度可控的保护层或钝化层,同时又不损伤或腐蚀体系表面,有望成为一种固态量子体系钝化或封装的方法.     

Generation of Entangled and Hyperentangled Bell States on Photon Systems Assisted by Diamond Nitrogen-Vacancy Centers Coupled with Whispering-Gallery-Mode Microresonators

International Journal of Theoretical Physics - Entanglement plays an important role in quantum information science and technology. Here we propose two schemes for the generation of entangled Bell...     

Rapid Measurement and Control of Nitrogen-Vacancy Center-Axial Orientation in Diamond Particles

Determination and control of nitrogen-vacancy(NV) centers play an important role in sensing the vector field by using their quantum information.To measure orientation of NV centers in a diamond particle attached to a tapered fiber rapidly,we propose a new method to establish the direction cosine matrix between the lab frame and the NV body frame.In this method,only four groups of the ODMR spectrum peaks shift data need to be collected,and the magnetic field along ±Z and ±Y in the lab frame is ap...     

A Controlled Phase Gate with Nitrogen-Vacancy Centers in Nanocrystal Coupled to a Silica Microsphere Cavity

We show how a controlled phase gate, induced by adiabatic passage of dark states, can be implemented with the nitrogen-vacancy defects in nanocrystal coupled to the optical whispering gallery mode in a silica microsphere cavity. The gate presented is robust to the fluctuations of the experimental parameters compared to the dynamical and geometric phases gates. The feasibility of this scheme is characterized by exact numerical simulations that incorporate various sources of experiment noise. The results demonstrate the practicality by way of current experimental technologies.     

Non-Geometric Conditional Phase Gate by Quantum Zeno Dynamics in Laser-Excited Nitrogen-Vacancy Centers

Based on the quantum Zeno dynamics,we propose a two-qubit non-geometric conditional phase gate between two nitrogen-vacancy centers coupled to a whispering-gallery mode cavity.The varying phases design of periodic laser can be used for realizing non-geometric conditional phase gate,and the cavity mode is virtually excited during the gate operation.Thus,the fidelity of the gate operation is insensitive to cavity decay and the fluctuation of the preset laser intensity.The numerical simulation with a realistic set of experimental parameters shows that the gate fidelity 0.987 can be within reached in the near future.     

Generation of Nitrogen-Vacancy Center Pairs in Bulk Diamond by Molecular Nitrogen Implantation

The coupled negatively charged nitrogen-vacancy(NV~-) center system is a promising candidate for scalable quantum information techniques.In this work,ionized nitrogen molecules are implanted into bulk diamond to generate coupled NV~- center pairs.The two-photon autocorrelation measurement and optically detected magnetic resonance measurement are carried out to confirm the production of the NV~- center pair.Also,both 1.3μs decoherence time and 4.9kHz magnetic coupling strength of the NV~- center pair are measured by controlling and detecting the spin states.Along with nanoscale manipulation and detection methods,such coupled NV~- centers through short distance dipole-dipole interaction would show high potential in scalable quantum information processes.     

Preparation of Macroscopic Entangled Coherent States in Nitrogen-Vacancy Centers Ensembles Coupled to a Superconducting Flux Qubit

We propose a potentially practical scheme for creating macroscopic entangled coherent state between two separate nitrogen-vacancy center spin ensembles placed near a superconducting flux qubit. Through the collective magnetic coupling and the in situ tunability of the flux qubit, the arbitrary entangled coherent states of spin ensembles can be achieved with high success possibilities under the influence from decoherence of the flux qubit and spin ensembles.The experimental feasibility and challenge are justified using currently available technology.     

Microwave Antenna for Exciting Optically Detected Magnetic Resonance in Diamond NV Centers

A microwave antenna configuration shaped as coaxial resonant coils is proposed for exciting magnetic dipole transitions of the optical ground state of the nitrogen—vacancy color center in diamond. The field within the antenna is simulated, field amplitudes are experimentally measured.     

Photoluminescence of Germanium-Vacancy Color Centers in Diamond Particles Obtained by Chemical Vapor Deposition

Physics of the Solid State - We synthesized diamond particles with germanium-vacancy color centers on a germanium substrate by hot-filament chemical vapor deposition. The formation of color centers...     

3D Uniform Manipulation of NV Centers in Diamond Using a Dielectric Resonator Antenna

Ensembles of nitrogen-vacancy color centers in diamond hold promise for ultra-precise magnetometry, competing with superconducting quantum interference device detectors. By utilizing the advantages of dielectric materials, such as very low losses for electromagnetic field, with the potential for creating high Q-factor resonators with strong concentration of the field within it, we implemented a dielectric resonator antenna for coherent manipulation of a large ensemble of nitrogen-vacancy centers in diamond. We reached average Rabi frequency of 10 MHz in a volume of 7 mm³ with a standard deviation of less than 1% at a moderate pump power. The obtained result enables use of large volume low nitrogen-vacancy concentration diamond plates in modern nitrogen-vacancy magnetometers thus improving sensitivity via larger coherence time and higher optical detected magnetic resonance contrast.     

New Data on the Nature of the EPR OK1 and N3 Centers in Diamond

The well-known diamond electron paramagnetic resonance (EPR) OK1 and N3 defects are discussed in the context of incorporation of heavy metal, supposedly Ti, in the double semivacancy and substitutional structures, respectively. X-ray phase analysis of inclusions of the growth medium, eclogite, in the diamonds under study shows an atypically high concentration of titanium compounds. To support proposed models, the hyperfine structure (HFS) from ¹³C in the OK1 center has been analyzed more precisely. The data obtained are consistent with attributing additional satellites around the main EPR lines to HFS from ⁴⁷Ti and ⁴⁹Ti. A double semivacancy model describes the directions of g and A tensor components of the OK1 center. The features of infrared and photoluminescence spectra related to the OK1/S1 and N3/440.3 nm centers are presented.     

气源分子束外延生长的InPBi薄膜材料中的深能级中心

利用深能级瞬态谱(DLTS)研究了气源分子束外延(GSMBE)生长的InP1-xBix材料中深能级中心的性质。在未有意掺杂的InP中测量到一个多数载流子深能级中心E1,E1的能级位置为Ec-0.38 e V,俘获截面为1.87×10~(-15)cm~2。在未有意掺杂的InP0.9751Bi0.0249中测量到一个少数载流子深能级中心H1,H1的能级位置为Ev+0.31 eV,俘获截面为2.87×10~(-17)cm~2。深中心E1应该起源于本征反位缺陷PIn,深中心H1可能来源于形成的Bi原子对或者更复杂的与Bi相关的团簇。明确这些缺陷的起源对于InPBi材料在器件应用方面具有重要的意义。     

一种特殊结构的金刚石薄膜电致发光器件

蓝色波段电致发光器件的研究是近年来光电子和材料科学研究领域最引入注目的研究课题之一。文章作者分别利用脉冲激光淀积设备和微波等离子体化学气相沉积设备制备了不同结构的高质量掺杂金刚石薄膜电致发光器件，并对其发光光谱特性，频率特性以及发光强度与杂质浓度及激发电压的依赖关系进行了研究，发现了金旬石薄膜紫外线的发光现象，取得了一系列有价值的结果。