High precision current measurement is very important for the calibration of various high-precision equipment and the measurement of other precision detection fields.A new current sensor based on diamond nitrogen-vacan...High precision current measurement is very important for the calibration of various high-precision equipment and the measurement of other precision detection fields.A new current sensor based on diamond nitrogen-vacancy(NV)color center magnetic measurement method is proposed to realize the accurate measurement of current.This new current method can greatly improve the accuracy of current measurement.Experiments show that the linearity of the current sensor based on diamond NV color center can reach up to 33 ppm,which is superior to other current sensors and solves the problem of low linearity.When the range of input current is 5-40 A,the absolute error of the calculated current is less than 51μA,and the relative error is 2.42×10^(-6) at 40 A.Combined with the research content and results of the experiment,the application of the current sensor in the field of current precision measurement is prospected.展开更多
Magnetic field measurement plays an extremely important role in material science,electronic en-gineering,power system and even industrial fields.In particular,magnetic field measurement provides a safe and reliable to...Magnetic field measurement plays an extremely important role in material science,electronic en-gineering,power system and even industrial fields.In particular,magnetic field measurement provides a safe and reliable tool for industrial non-destructive testing.The sensitivity of magnetic field measurement deter-mines the highest level of detection.The diamond nitrogen-vacancy(NV)color center is a new type of quan-tum sensor developed in recent years.The external magnetic field will cause Zeeman splitting of the ground state energy level of the diamond NV color center.Optical detection magnetic resonance(ODMR),using a mi-crowave source and a lock-in amplifier to detect the resonant frequency of the NV color center,and finally the change of the resonant frequency can accurately calculate the size of the external magnetic field and the sensi-tivity of the external magnetic field change.In the experiment,a diamond containing a high concentration of NV color centers is coupled with an optical fiber to realize the preparation of a magnetic field scanning probe.Then,the surface cracks of the magnetized iron plate weld are scanned,and the scanning results are drawn into a two-dimensional magnetic force distribution map,according to the magnetic field gradient change of the magnetic force distribution map,the position and size of the crack can be judged very accurately,which pro-vides a very effective diagnostic tool for industrial safety.展开更多
We present the experimental results of nitrogen-vacancy （NV） electron spin decoherence, which are linked to the coexistence of electron spin bath of nitrogen impurity （PI center） and 13C nuclear spin bath. In prev...We present the experimental results of nitrogen-vacancy （NV） electron spin decoherence, which are linked to the coexistence of electron spin bath of nitrogen impurity （PI center） and 13C nuclear spin bath. In previous works, only one dominant decoherence source is studied： P1 electron spin bath for type-Ⅰb diamond; or 13C nuclear spin bath for type-Ⅱa diamond. In general, the thermal fluctuation from both spin baths can be eliminated by the Hahn echo sequence, resulting in a long coherence time （T2 ） of about 400#8. However, in a high-purity type-Ⅱa diamond where 1℃ nuclear spin bath is the dominant decoherence source, dramatic decreases of NV electron spin T2 time caused by P1 electron spin bath are observed under certain magnetic field. We further apply the engineered Hahn echo sequence to confirm the decoherenee mechanism of multiple spin baths and quantitatively estimate the contribution of P1 electron spin bath. Our results are helpful to understand the NV decoherence mechanisms, which will benefit quantum computing and quantum metrology.展开更多
We develop a design of a hybrid quantum interface for quantum information transfer （QIT）, adopting a nanome- chanical resonator as the intermedium, which is magnetically coupled with individual nitrogen-vacancy cent...We develop a design of a hybrid quantum interface for quantum information transfer （QIT）, adopting a nanome- chanical resonator as the intermedium, which is magnetically coupled with individual nitrogen-vacancy centers as the solid qubits, while eapacitively coupled with a coplanar waveguide resonator as the quantum data bus. We describe the Hamiltonian of the model, and analytically demonstrate the QIT for both the resonant interaction and large detuning cases. The hybrid quantum interface allows for QIT between arbitrarily selected individual nitrogen-vacancy centers, and has advantages of the sealability and controllability. Our methods open an alter- native perspective for implementing QIT, which is important during quantum storing or processing procedures in quantum computing.展开更多
We design proposals to generate a remote Greenberger-Horne-Zeilinger（GHZ） state and a W state of nitrogenvacancy（NV） centers coupled to microtoroidal resonators（MTRs） through noisy channels by utilizing time-bin...We design proposals to generate a remote Greenberger-Horne-Zeilinger（GHZ） state and a W state of nitrogenvacancy（NV） centers coupled to microtoroidal resonators（MTRs） through noisy channels by utilizing time-bin encoding processes and fast-optical-switch-based polarization rotation operations.The polarization and phase noise induced by noisy channels generally affect the time of state generation but not its success probability and fidelity.Besides,the above proposals can be generalized to n-qubit between two or among n remote nodes with success probability unity under ideal conditions.Furthennore,the proposals are robust for regular noise-changeable channels for the n-node case.This method is also useful in other remote quantum information processing tasks through noisy channels.展开更多
An integrated quantum probe for magnetic field imaging is proposed,where the nitrogen–vacancy(NV)center fixed at the fiber tip is located on the periphery of flexible ring resonator.Using flexible polyimide(PI)as the...An integrated quantum probe for magnetic field imaging is proposed,where the nitrogen–vacancy(NV)center fixed at the fiber tip is located on the periphery of flexible ring resonator.Using flexible polyimide(PI)as the substrate medium,we design a circular microstrip antenna,which can achieve a bandwidth of 140 MHz at Zeeman splitting frequency of 2.87 GHz,specifically suitable for NV center experiments.Subsequently,this antenna is seamlessly fixed at a three-dimensional-printed cylindrical support,allowing the optical fiber tip to extend out of a dedicated aperture.To mitigate errors originating from processing,precise tuning within a narrow range can be achieved by adjusting the conformal amplitude.Finally,we image the microwave magnetic field around the integrated probe with high resolution,and determine the suitable area for placing the fiber tip(SAP).展开更多
Fast and high fidelity quantum control is the key technology of quantum computing. The hybrid system composed of the nitrogen-vacancy center and nearby Carbon-13 nuclear spin is expected to solve this problem. The nit...Fast and high fidelity quantum control is the key technology of quantum computing. The hybrid system composed of the nitrogen-vacancy center and nearby Carbon-13 nuclear spin is expected to solve this problem. The nitrogen-vacancy center electron spin enables fast operations for its strong coupling to the control field, whereas the nuclear spins preserve the coherence for their weak coupling to the environment. In this paper, we describe a strategy to achieve time-optimal control of the Carbon-13 nuclear spin qubit by alternating controlling the nitrogen-vacancy center electron spin as an actuator. We transform the qubit gate operation into a switched system. By using the maximum principle, we study the minimum time control of the switched system and obtain the time-optimal control of the qubit gate operation. We show that the X gate and Y gate operations are within 10μs while the fidelity reaches 0.995.展开更多
This work demonstrates a micron-sized nanosecond current pulse probe using a quantum diamond magnetometer.A micron-sized diamond crystal affixed to a fiber tip is integrated on the end of a conical waveguide.We demons...This work demonstrates a micron-sized nanosecond current pulse probe using a quantum diamond magnetometer.A micron-sized diamond crystal affixed to a fiber tip is integrated on the end of a conical waveguide.We demonstrate real-time visualization of a single 100 nanosecond pulse and discrimination of two pulse trains of different frequencies with a coplanar waveguide and a home-made PCB circuit.This technique finds promising applications in the display of electronic stream and can be used as a pulse discriminator to simultaneously receive and demodulate multiple pulse frequencies.This method of detecting pulse current is expected to provide further detailed analysis of the internal working state of the chip.展开更多
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 ...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.展开更多
Nitrogen-vacancy(NV)centers in a bulk diamond are often employed to realize measurement of multiple physical quantities,which depends on orientation information of NV axis.We report a fast and effective method to dete...Nitrogen-vacancy(NV)centers in a bulk diamond are often employed to realize measurement of multiple physical quantities,which depends on orientation information of NV axis.We report a fast and effective method to determine the orientation of NV axis with the aid of a static magnetic field.By measuring the optically detected magnetic resonance spectra,we can precisely extract the polar angle information between the NV axis and the known magnetic field.Combining with the polar angle information of different kinds of NV centers,we employ the Nelder-Mead algorithm to get the optimal solution of the orientation of NV axis.This method is simple and efficient,and is easily applied in NV-based quantum sensing.展开更多
Single-photon flux is one of the crucial properties of nitrogen vacancy （NV） centers in diamond for its application in quantum information techniques. Here we fabricate diamond conical nanowires to enhance the singl...Single-photon flux is one of the crucial properties of nitrogen vacancy （NV） centers in diamond for its application in quantum information techniques. Here we fabricate diamond conical nanowires to enhance the single-photon count rate. Through the interaction between tightly confined optical mode in nanowires and NV centers, the single-photon lifetime is much shortened and the collection efficiency is enhanced. As a result, the detected single-photon rate can be at 564 kcps, and the total detection coefficient can be 0.8%, which is much higher than that in bulk diamond. Such a nanowire single-photon device with high photon flux can be applied to improve the fidelity of quantum computation and the precision of quantum sensors.展开更多
In this review, we briefly review recent works on hybrid （nano） and diamond nitrogen-vacancy （NV） centers. We also review opto-mechanical systems that contain both mechanical oscillators two different types of mec...In this review, we briefly review recent works on hybrid （nano） and diamond nitrogen-vacancy （NV） centers. We also review opto-mechanical systems that contain both mechanical oscillators two different types of mechanical oscillators. The first one is a clamped mechanical oscillator, such as a cantilever, with a fixed frequency. The second one is an optically trapped nano-diamond with a built-in nitrogen-vacancy center. By coupling mechanical resonators with electron spins, we can use the spins to control the motion of mechanical oscillators. For the first setup, we discuss two different coupling mechanisms, which are magnetic coupling and strain induced coupling. We summarize their applications such as cooling the mechanical oscillator, generating entanglements between NV centers, squeezing spin ensembles etc. For the second setup, we discuss how to generate quantum superposition states with magnetic coupling, and realize matter wave interferometer. We will also review its applications as ultra-sensitive mass spectrometer. Finally, we discuss new coupling mechanisms and applications of the field.展开更多
We propose a potentially practical scheme for efcient generation of entanglement with two nitrogen-vacancy centers(NVC)coupled to a whispering-gallery mode cavity.By virtue of the virtual-photon-excitation,the entangl...We propose a potentially practical scheme for efcient generation of entanglement with two nitrogen-vacancy centers(NVC)coupled to a whispering-gallery mode cavity.By virtue of the virtual-photon-excitation,the entanglement with two separate NVC can be produced in a deterministic way.The required operations are very close to the capabilities of current experimental techniques.The efects of decoherence induced by the cavity decay and the atomic spontaneous decay are also investigated.展开更多
Femtosecond laser direct writing provides an efficient approach to fabricating single nitrogen vacancy(NV) color centers with a relatively high yield. Different from previously reported NV color centers with a random ...Femtosecond laser direct writing provides an efficient approach to fabricating single nitrogen vacancy(NV) color centers with a relatively high yield. Different from previously reported NV color centers with a random distribution in a bulk diamond or nanocrystals, this gives an opportunity to study the photophysical properties of single NV color centers with precise numbers and positions. However, ultrafast studies on single NV color centers prepared by localization femtosecond laser direct writing are still rare, especially for the graphitization inside a diamond and its relationship with single NV color centers. Here, we report the broadband transient absorption(TA) spectroscopic features of the graphitization and NV color centers in a diamond fabricated by localization femtosecond laser direct writing at room temperature under 400 nm excitation. In comparison with the graphene oxide film, the bleaching features of the graphitization point array in a diamond are similar to reduced graphene oxide,accompanied by excited state absorption signals from local carbon atom vacancy defects in graphene-like structures induced by laser writing. On the other hand, transient features of laser processing array containing single NV color centers with a yield of~50% are different from those of the graphitization point array. Our findings suggest that for ultrashort pulse processing of diamonds, broadband TA spectral signals are sensitive to the surrounding atomic environment of processing sites, which could be applied to laser writing point defects in other materials used as solid-state single photon sources.展开更多
Because of quantum superposition, quantum computation can solve many problems, such as factoring large integers [ 1 ] and searching unsorted databases [2,3], much faster than clas- sical computation. To realize practi...Because of quantum superposition, quantum computation can solve many problems, such as factoring large integers [ 1 ] and searching unsorted databases [2,3], much faster than clas- sical computation. To realize practical quantum computation and then gain the desired advantages, a universal set of quantum gates with sufficiently high fidelities are needed. However, various inevitable errors reduce the gate fidelities and finally collapse the computation results, which makes the realizations of quantum computation very challenging.展开更多
This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operat...This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operation and compact integration,restricting the sensitivity and dynamic range of the sensor.The broadband antenna based on a dualfrequency monopole structure achieves a bandwidth extension of 777 MHz at the Zeeman splitting frequency of 2.87 GHz,with the dual resonant points positioned near 2.87 GHz.Additionally,high-resolution imaging of the microwave magnetic field on the antenna surface was performed using a diamond optical fiber probe,which verified the dual-frequency design principle.Experimental results using the proposed antenna demonstrate the outstanding performance of the NV centerbased magnetic sensor:a sensitivity of 55 nT/Hz^(1/2)and a dynamic range of up to 54.0 dB.Compared to sensors using conventional antennas,the performance has been significantly improved.展开更多
Combining optical tweezers with fluorescence microscopy is a powerful tool for single-cell analysis,playing a pivotal role in disease diagnosis,cell sorting,and the investigation of cellular dynamics.However,fluoresce...Combining optical tweezers with fluorescence microscopy is a powerful tool for single-cell analysis,playing a pivotal role in disease diagnosis,cell sorting,and the investigation of cellular dynamics.However,fluorescence detection faces challenges such as blinking,photobleaching and autofluorescence in biotissues.To address these limitations,we developed a magnetic detection strategy by integrating quantum magnetometry using nitrogen-vacancy centers into optical tweezers,demonstrating precise trapping and manipulation of individual cells in microfluidic environment.We detected a magnetic signal of 89μT from a single cell labeled with magnetic nanoparticles,compared to a noise floor of 3.9μT observed in unlabeled cells.This platform provides a promising approach for high-precision single-cell analysis and holds significant potential for probing cellular activities within biological microenvironments.展开更多
Diamond negatively charged nitrogen-vacancy(NV-) centers provide an opportunity for the measurement of the Meissner effect on extremely small samples in a diamond anvil cell(DAC) due to their high sensitivity in detec...Diamond negatively charged nitrogen-vacancy(NV-) centers provide an opportunity for the measurement of the Meissner effect on extremely small samples in a diamond anvil cell(DAC) due to their high sensitivity in detecting the tiny change of magnetic field. We report on the variation of magnetic field distribution in a DAC as a sample transforms from normal to superconducting state by using finite element analysis. The results show that the magnetic flux density has the largest change on the sidewall of the sample, where NV-centers can detect the strongest signal variation of the magnetic field. In addition, we study the effect of magnetic coil placement on the magnetic field variation. It is found that the optimal position for the coil to generate the greatest change in magnetic field strength is at the place as close to the sample as possible.展开更多
Crystallization of diamond with different nitrogen concentrations was carried out with a FeNiCo-C system at pressure of 6.5 GPa.As the nitrogen concentration in diamond increased,the color of the synthesized diamond c...Crystallization of diamond with different nitrogen concentrations was carried out with a FeNiCo-C system at pressure of 6.5 GPa.As the nitrogen concentration in diamond increased,the color of the synthesized diamond crystals changed from colorless to yellow and finally to atrovirens(a dark green).All the Raman peaks for the obtained crystals were located at about 1330 cm^(-1)and contained only the sp^(3)hybrid diamond phase.Based on Fourier transform infrared results,the nitrogen concentration of the colorless diamond was<1 ppm and absorption peaks corresponding to nitrogen impurities were not detected.However,the C-center nitrogen concentration of the atrovirens diamond reached 1030 ppm and the value of A-center nitrogen was approximately 180 ppm with a characteristic absorption peak at 1282 cm^(-1).Furthermore,neither the NV^(0)nor the NV^(-)optical color center existed in diamond crystal with nitrogen impurities of less than 1 ppm by photoluminescence measurement.However,Ni-related centers located at 695 nm and 793.6 nm were observed in colorless diamond.The NE8 color center at 793.6 nm has more potential for application than the common NV centers.NV^(0)and NV^(-)optical color centers coexist in diamond without any additives in the synthesis system.Importantly,only the NV^(-)color center was noticed in diamond with a higher nitrogen concentration,which maximized optimization of the NV^(-)/NV^(0)ratio in the diamond structure.This study has provided a new way to prepare diamond containing only NV^(-)optical color centers.展开更多
Nitrogen-vacancy （NV） center in diamond is one of the most promising candidates to implement room temperature quantum computing. In this review, we briefly discuss the working principles and recent experimental prog...Nitrogen-vacancy （NV） center in diamond is one of the most promising candidates to implement room temperature quantum computing. In this review, we briefly discuss the working principles and recent experimental progresses of this spin qubit. These results focus on understanding and prolonging center spin coherence, steering and probing spin states with dedicated quantum control techniques, and exploiting the quantum nature of these multi-spin systems, such as superposition and entanglement, to demonstrate the superiority of quantum information processing. Those techniques also stimulate the fast development of NV-based quantum sensing, which is an interdisciplinary field with great potential applications.展开更多
基金Project supported in part by the National Natural Science Foundation of China(Grant Nos.51922009,51727808,62175219,62103385,and 51821003)the Key Laboratory of Shanxi Province(Grant No.201905D121001)the Shanxi‘1331 Project’Key Subjects Construction.
文摘High precision current measurement is very important for the calibration of various high-precision equipment and the measurement of other precision detection fields.A new current sensor based on diamond nitrogen-vacancy(NV)color center magnetic measurement method is proposed to realize the accurate measurement of current.This new current method can greatly improve the accuracy of current measurement.Experiments show that the linearity of the current sensor based on diamond NV color center can reach up to 33 ppm,which is superior to other current sensors and solves the problem of low linearity.When the range of input current is 5-40 A,the absolute error of the calculated current is less than 51μA,and the relative error is 2.42×10^(-6) at 40 A.Combined with the research content and results of the experiment,the application of the current sensor in the field of current precision measurement is prospected.
基金supported by the Provincial Control Technology Project No.52120519002N.
文摘Magnetic field measurement plays an extremely important role in material science,electronic en-gineering,power system and even industrial fields.In particular,magnetic field measurement provides a safe and reliable tool for industrial non-destructive testing.The sensitivity of magnetic field measurement deter-mines the highest level of detection.The diamond nitrogen-vacancy(NV)color center is a new type of quan-tum sensor developed in recent years.The external magnetic field will cause Zeeman splitting of the ground state energy level of the diamond NV color center.Optical detection magnetic resonance(ODMR),using a mi-crowave source and a lock-in amplifier to detect the resonant frequency of the NV color center,and finally the change of the resonant frequency can accurately calculate the size of the external magnetic field and the sensi-tivity of the external magnetic field change.In the experiment,a diamond containing a high concentration of NV color centers is coupled with an optical fiber to realize the preparation of a magnetic field scanning probe.Then,the surface cracks of the magnetized iron plate weld are scanned,and the scanning results are drawn into a two-dimensional magnetic force distribution map,according to the magnetic field gradient change of the magnetic force distribution map,the position and size of the crack can be judged very accurately,which pro-vides a very effective diagnostic tool for industrial safety.
基金Supported by the National Basic Research Program of China under Grant Nos 2014CB921402 and 2015CB921103the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant No XDB07010300the National Natural Science Foundation of China under Grant No 11574386
文摘We present the experimental results of nitrogen-vacancy （NV） electron spin decoherence, which are linked to the coexistence of electron spin bath of nitrogen impurity （PI center） and 13C nuclear spin bath. In previous works, only one dominant decoherence source is studied： P1 electron spin bath for type-Ⅰb diamond; or 13C nuclear spin bath for type-Ⅱa diamond. In general, the thermal fluctuation from both spin baths can be eliminated by the Hahn echo sequence, resulting in a long coherence time （T2 ） of about 400#8. However, in a high-purity type-Ⅱa diamond where 1℃ nuclear spin bath is the dominant decoherence source, dramatic decreases of NV electron spin T2 time caused by P1 electron spin bath are observed under certain magnetic field. We further apply the engineered Hahn echo sequence to confirm the decoherenee mechanism of multiple spin baths and quantitatively estimate the contribution of P1 electron spin bath. Our results are helpful to understand the NV decoherence mechanisms, which will benefit quantum computing and quantum metrology.
基金Supported by the National Natural Science Foundation of China under Grant No 11305021the Fundamental Research Funds for the Central Universities of China under Grants Nos 3132014229 and 3132014328
文摘We develop a design of a hybrid quantum interface for quantum information transfer （QIT）, adopting a nanome- chanical resonator as the intermedium, which is magnetically coupled with individual nitrogen-vacancy centers as the solid qubits, while eapacitively coupled with a coplanar waveguide resonator as the quantum data bus. We describe the Hamiltonian of the model, and analytically demonstrate the QIT for both the resonant interaction and large detuning cases. The hybrid quantum interface allows for QIT between arbitrarily selected individual nitrogen-vacancy centers, and has advantages of the sealability and controllability. Our methods open an alter- native perspective for implementing QIT, which is important during quantum storing or processing procedures in quantum computing.
基金supported by the National Natural Science Foundation of China(Grant Nos.11264042,61465013,11465020,and 11165015)the Program for Chun Miao Excellent Talents of Jilin Provincial Department of Education(Grant No.201316)the Talent Program of Yanbian University of China(Grant No.950010001)
文摘We design proposals to generate a remote Greenberger-Horne-Zeilinger（GHZ） state and a W state of nitrogenvacancy（NV） centers coupled to microtoroidal resonators（MTRs） through noisy channels by utilizing time-bin encoding processes and fast-optical-switch-based polarization rotation operations.The polarization and phase noise induced by noisy channels generally affect the time of state generation but not its success probability and fidelity.Besides,the above proposals can be generalized to n-qubit between two or among n remote nodes with success probability unity under ideal conditions.Furthennore,the proposals are robust for regular noise-changeable channels for the n-node case.This method is also useful in other remote quantum information processing tasks through noisy channels.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFB2012600)the Science and Technology Plan Project of State Administration of Market Regulation,China(Grant No.2021MK039)。
文摘An integrated quantum probe for magnetic field imaging is proposed,where the nitrogen–vacancy(NV)center fixed at the fiber tip is located on the periphery of flexible ring resonator.Using flexible polyimide(PI)as the substrate medium,we design a circular microstrip antenna,which can achieve a bandwidth of 140 MHz at Zeeman splitting frequency of 2.87 GHz,specifically suitable for NV center experiments.Subsequently,this antenna is seamlessly fixed at a three-dimensional-printed cylindrical support,allowing the optical fiber tip to extend out of a dedicated aperture.To mitigate errors originating from processing,precise tuning within a narrow range can be achieved by adjusting the conformal amplitude.Finally,we image the microwave magnetic field around the integrated probe with high resolution,and determine the suitable area for placing the fiber tip(SAP).
基金This work was supported by the National Natural Science Foundation of China （Nos. 61227902, 61573343） and the National Center for Mathematics and Interdisciplinary Sciences, CAS.
文摘Fast and high fidelity quantum control is the key technology of quantum computing. The hybrid system composed of the nitrogen-vacancy center and nearby Carbon-13 nuclear spin is expected to solve this problem. The nitrogen-vacancy center electron spin enables fast operations for its strong coupling to the control field, whereas the nuclear spins preserve the coherence for their weak coupling to the environment. In this paper, we describe a strategy to achieve time-optimal control of the Carbon-13 nuclear spin qubit by alternating controlling the nitrogen-vacancy center electron spin as an actuator. We transform the qubit gate operation into a switched system. By using the maximum principle, we study the minimum time control of the switched system and obtain the time-optimal control of the qubit gate operation. We show that the X gate and Y gate operations are within 10μs while the fidelity reaches 0.995.
基金Project supported by the National Key R&D Program of China(Grant No.2021YFB2012600)。
文摘This work demonstrates a micron-sized nanosecond current pulse probe using a quantum diamond magnetometer.A micron-sized diamond crystal affixed to a fiber tip is integrated on the end of a conical waveguide.We demonstrate real-time visualization of a single 100 nanosecond pulse and discrimination of two pulse trains of different frequencies with a coplanar waveguide and a home-made PCB circuit.This technique finds promising applications in the display of electronic stream and can be used as a pulse discriminator to simultaneously receive and demodulate multiple pulse frequencies.This method of detecting pulse current is expected to provide further detailed analysis of the internal working state of the chip.
基金Supported by the National Science Foundation of China under Grant No.11374118
文摘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.
基金This work was supported by the National Key R&D Program of China(Grant No.2020YFA0309400)the National Natural Science Foundation of China(Grant No.12174081)the Fundamental Research Funds for the Central Universities(Grant Nos.JZ2021HGTB0126 and PA2021KCPY0052).
文摘Nitrogen-vacancy(NV)centers in a bulk diamond are often employed to realize measurement of multiple physical quantities,which depends on orientation information of NV axis.We report a fast and effective method to determine the orientation of NV axis with the aid of a static magnetic field.By measuring the optically detected magnetic resonance spectra,we can precisely extract the polar angle information between the NV axis and the known magnetic field.Combining with the polar angle information of different kinds of NV centers,we employ the Nelder-Mead algorithm to get the optimal solution of the orientation of NV axis.This method is simple and efficient,and is easily applied in NV-based quantum sensing.
基金Supported by the National Key Research and Development Program of China under Grant No 2017YFA0304504the National Natural Science Foundation of China under Grant Nos 11374290,61522508,91536219 and 11504363
文摘Single-photon flux is one of the crucial properties of nitrogen vacancy （NV） centers in diamond for its application in quantum information techniques. Here we fabricate diamond conical nanowires to enhance the single-photon count rate. Through the interaction between tightly confined optical mode in nanowires and NV centers, the single-photon lifetime is much shortened and the collection efficiency is enhanced. As a result, the detected single-photon rate can be at 564 kcps, and the total detection coefficient can be 0.8%, which is much higher than that in bulk diamond. Such a nanowire single-photon device with high photon flux can be applied to improve the fidelity of quantum computation and the precision of quantum sensors.
基金supported by the National Basic Research Program of China(Grant Nos.2011CBA00300 and 2011CBA00302)the National Natural Science Foundation of China(Grant Nos.11105136,61435007,11374032 and11121403)+1 种基金the National Key Basic Research Program of China(Grant No.2014CB848700)the support given by Purdue University through the startup fund
文摘In this review, we briefly review recent works on hybrid （nano） and diamond nitrogen-vacancy （NV） centers. We also review opto-mechanical systems that contain both mechanical oscillators two different types of mechanical oscillators. The first one is a clamped mechanical oscillator, such as a cantilever, with a fixed frequency. The second one is an optically trapped nano-diamond with a built-in nitrogen-vacancy center. By coupling mechanical resonators with electron spins, we can use the spins to control the motion of mechanical oscillators. For the first setup, we discuss two different coupling mechanisms, which are magnetic coupling and strain induced coupling. We summarize their applications such as cooling the mechanical oscillator, generating entanglements between NV centers, squeezing spin ensembles etc. For the second setup, we discuss how to generate quantum superposition states with magnetic coupling, and realize matter wave interferometer. We will also review its applications as ultra-sensitive mass spectrometer. Finally, we discuss new coupling mechanisms and applications of the field.
基金supported by the National Natural Science Foundation of China(Grant Nos.10874122 and 11372122)the Program for Excellent Talents at the University of Guangdong Province(Guangdong Teacher Letter[1010]No.79)
文摘We propose a potentially practical scheme for efcient generation of entanglement with two nitrogen-vacancy centers(NVC)coupled to a whispering-gallery mode cavity.By virtue of the virtual-photon-excitation,the entanglement with two separate NVC can be produced in a deterministic way.The required operations are very close to the capabilities of current experimental techniques.The efects of decoherence induced by the cavity decay and the atomic spontaneous decay are also investigated.
基金supported by the National Natural Science Foundation of China (Grant Nos. 62175088, 61927814, 21773087, 21603083, 21903035)China Postdoctoral Science Foundation (Grant No. 2016M590259)。
文摘Femtosecond laser direct writing provides an efficient approach to fabricating single nitrogen vacancy(NV) color centers with a relatively high yield. Different from previously reported NV color centers with a random distribution in a bulk diamond or nanocrystals, this gives an opportunity to study the photophysical properties of single NV color centers with precise numbers and positions. However, ultrafast studies on single NV color centers prepared by localization femtosecond laser direct writing are still rare, especially for the graphitization inside a diamond and its relationship with single NV color centers. Here, we report the broadband transient absorption(TA) spectroscopic features of the graphitization and NV color centers in a diamond fabricated by localization femtosecond laser direct writing at room temperature under 400 nm excitation. In comparison with the graphene oxide film, the bleaching features of the graphitization point array in a diamond are similar to reduced graphene oxide,accompanied by excited state absorption signals from local carbon atom vacancy defects in graphene-like structures induced by laser writing. On the other hand, transient features of laser processing array containing single NV color centers with a yield of~50% are different from those of the graphitization point array. Our findings suggest that for ultrashort pulse processing of diamonds, broadband TA spectral signals are sensitive to the surrounding atomic environment of processing sites, which could be applied to laser writing point defects in other materials used as solid-state single photon sources.
文摘Because of quantum superposition, quantum computation can solve many problems, such as factoring large integers [ 1 ] and searching unsorted databases [2,3], much faster than clas- sical computation. To realize practical quantum computation and then gain the desired advantages, a universal set of quantum gates with sufficiently high fidelities are needed. However, various inevitable errors reduce the gate fidelities and finally collapse the computation results, which makes the realizations of quantum computation very challenging.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFB2012600)the Science and Technology Plan Project of the State Administration of Market Regulation,China(Grant No.2021MK039)the Suqian Talent Elite Program(Grant No.SQQN202414)。
文摘This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operation and compact integration,restricting the sensitivity and dynamic range of the sensor.The broadband antenna based on a dualfrequency monopole structure achieves a bandwidth extension of 777 MHz at the Zeeman splitting frequency of 2.87 GHz,with the dual resonant points positioned near 2.87 GHz.Additionally,high-resolution imaging of the microwave magnetic field on the antenna surface was performed using a diamond optical fiber probe,which verified the dual-frequency design principle.Experimental results using the proposed antenna demonstrate the outstanding performance of the NV centerbased magnetic sensor:a sensitivity of 55 nT/Hz^(1/2)and a dynamic range of up to 54.0 dB.Compared to sensors using conventional antennas,the performance has been significantly improved.
基金Project supported by the the National Key R&D Program of China(Grant Nos.2019YFA0709300 and 2021YFB3202800)the National Natural Science Foundation of China(Grant Nos.T2125011 and 12174377)+4 种基金the Chinese Academy of Sciences(Grant No.YSBR-068)Innovation Program for Quantum Science and Technology(GrantNos.2021ZD0302200 and 2021ZD0303204)New Cornerstone Science Foundation through the XPLORER PRIZEScience and Technology Department of Zhejiang Province(Grant No.2025C01041)the Fundamental Research Funds for the Central Universities(Grant No.226-2024-00142)。
文摘Combining optical tweezers with fluorescence microscopy is a powerful tool for single-cell analysis,playing a pivotal role in disease diagnosis,cell sorting,and the investigation of cellular dynamics.However,fluorescence detection faces challenges such as blinking,photobleaching and autofluorescence in biotissues.To address these limitations,we developed a magnetic detection strategy by integrating quantum magnetometry using nitrogen-vacancy centers into optical tweezers,demonstrating precise trapping and manipulation of individual cells in microfluidic environment.We detected a magnetic signal of 89μT from a single cell labeled with magnetic nanoparticles,compared to a noise floor of 3.9μT observed in unlabeled cells.This platform provides a promising approach for high-precision single-cell analysis and holds significant potential for probing cellular activities within biological microenvironments.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0305900)the National Natural Science Foundation of China(Grant Nos.11774126,11674404,and 51772125)
文摘Diamond negatively charged nitrogen-vacancy(NV-) centers provide an opportunity for the measurement of the Meissner effect on extremely small samples in a diamond anvil cell(DAC) due to their high sensitivity in detecting the tiny change of magnetic field. We report on the variation of magnetic field distribution in a DAC as a sample transforms from normal to superconducting state by using finite element analysis. The results show that the magnetic flux density has the largest change on the sidewall of the sample, where NV-centers can detect the strongest signal variation of the magnetic field. In addition, we study the effect of magnetic coil placement on the magnetic field variation. It is found that the optimal position for the coil to generate the greatest change in magnetic field strength is at the place as close to the sample as possible.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12064038 and 52072113)the Natural Science Foundation of Guizhou Province Science and Technology Agency(Grant Nos.ZK[2021]019 and ZK[2021]031)+1 种基金the Outstanding Young Science and Technology Talents of Guizhou Pronice,China(Grant No.[2019]5673)the Open Project of Inner Mongolia Key Lab of High-pressure Phase Functional Materials(Grant No.cfxygy202004)。
文摘Crystallization of diamond with different nitrogen concentrations was carried out with a FeNiCo-C system at pressure of 6.5 GPa.As the nitrogen concentration in diamond increased,the color of the synthesized diamond crystals changed from colorless to yellow and finally to atrovirens(a dark green).All the Raman peaks for the obtained crystals were located at about 1330 cm^(-1)and contained only the sp^(3)hybrid diamond phase.Based on Fourier transform infrared results,the nitrogen concentration of the colorless diamond was<1 ppm and absorption peaks corresponding to nitrogen impurities were not detected.However,the C-center nitrogen concentration of the atrovirens diamond reached 1030 ppm and the value of A-center nitrogen was approximately 180 ppm with a characteristic absorption peak at 1282 cm^(-1).Furthermore,neither the NV^(0)nor the NV^(-)optical color center existed in diamond crystal with nitrogen impurities of less than 1 ppm by photoluminescence measurement.However,Ni-related centers located at 695 nm and 793.6 nm were observed in colorless diamond.The NE8 color center at 793.6 nm has more potential for application than the common NV centers.NV^(0)and NV^(-)optical color centers coexist in diamond without any additives in the synthesis system.Importantly,only the NV^(-)color center was noticed in diamond with a higher nitrogen concentration,which maximized optimization of the NV^(-)/NV^(0)ratio in the diamond structure.This study has provided a new way to prepare diamond containing only NV^(-)optical color centers.
基金Project supported by the National Basic Research Program of China(Grant Nos.2014CB921402 and 2015CB921103)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB07010300)+1 种基金the National Natural Science Foundation of China(Grant No.11574386)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB0803)
文摘Nitrogen-vacancy （NV） center in diamond is one of the most promising candidates to implement room temperature quantum computing. In this review, we briefly discuss the working principles and recent experimental progresses of this spin qubit. These results focus on understanding and prolonging center spin coherence, steering and probing spin states with dedicated quantum control techniques, and exploiting the quantum nature of these multi-spin systems, such as superposition and entanglement, to demonstrate the superiority of quantum information processing. Those techniques also stimulate the fast development of NV-based quantum sensing, which is an interdisciplinary field with great potential applications.
