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
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
We describe a high efcient entanglement concentration protocol(ECP)for multi-particle less-entangled nitrogen-vacancy(N-V)center and microtoroidal resonator system.In the ECP,we only require one pair of less-entangled...We describe a high efcient entanglement concentration protocol(ECP)for multi-particle less-entangled nitrogen-vacancy(N-V)center and microtoroidal resonator system.In the ECP,we only require one pair of less-entangled state,two auxiliary N-V center in microcavities and some single photons.After the photon passing through the microcavity,by measuring the polarization of the photon,a maximally entangled W state can be obtained with some success probability.This ECP does not need to destroy the solid qubit,which makes it more feasible.Moreover,by resorting to more single photons,it can be repeated to reach a high success probability.These features make this ECP useful in current long-distance quantum communications.展开更多
The measurement of the weak magnetic field in nanoscale resolution and at room temperature is always a significant topic in biological, physical, and material science. Such detection can be used to decide the characte...The measurement of the weak magnetic field in nanoscale resolution and at room temperature is always a significant topic in biological, physical, and material science. Such detection can be used to decide the characterization of the samples, such as cells, materials, and so on. Nitrogen-vacancy (NV) center in diamond has been proved to be able to detect a magnetic field with nano Tesla sensitivity and nanometer resolution at room temperature. Here we experimentally demonstrate an optimized NV center based single electron magnetometer in a commercial diamond and under a home-built optically detected magnetic resonance (ODMR) microscope. With current technology, we change the optically detected time window to get a better signal to noise ratio, and use dynamical decoupling to increase the slope of magnetic field amplitude versus fluorescence signal. By employing the 8-pulse XY-4 dynamical decoupling sequence we achieve a sensitivity of 18.9 nT (Hz)(1/2) , which is 1.7 times better than spin echo. We also propose a NV center based scanning diamond microscope for electron and nuclear spins detection as well as nanoscale magnetic resonance imaging. If it is realized, the NV center based magnetometry will have wide application in the future.展开更多
The spin in a rotating frame has attracted a lot of attentions recently,as it deeply relates to both fundamental physics such as pseudo-magnetic field and geometric phase,and applications such as gyroscopic sensors.Ho...The spin in a rotating frame has attracted a lot of attentions recently,as it deeply relates to both fundamental physics such as pseudo-magnetic field and geometric phase,and applications such as gyroscopic sensors.However,previous studies only focused on adiabatic limit,where the rotating frequency is much smaller than the spin frequency.Here we propose to use a levitated nano-diamond with a built-in nitrogen-vacancy(NV)center to study the dynamics and the geometric phase of a rotating electron spin without adiabatic approximation.We find that the transition between the spin levels appears when the rotating frequency is comparable to the spin frequency at zero magnetic field.Then we use Floquet theory to numerically solve the spin energy spectrum,study the spin dynamics and calculate the geometric phase under a finite magnetic field,where the rotating frequency to induce resonant transition could be greatly reduced.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
Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing （QIP） tasks. Recently, a novel solid-state cavity quantum electrodynamics （QED） ...Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing （QIP） tasks. Recently, a novel solid-state cavity quantum electrodynamics （QED） system, in which the nitrogen-vacancy （NV） center in diamond is coupled to a microtoroidal resonator （MTR）, has been proposed as a poten- tial system for hybrid quantum information and computing. By virtue of such systems, we present a scheme to realize a nonlocal N-qubit conditional phase gate directly. Our scheme employs a cavity input-output process and single-photon interference, without the use of any auxiliary entanglement pair or classical communication. Considering the currently available technologies, our scheme might be quite useful among different nodes in quantum networks for large-scaled QIP.展开更多
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.
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supported by the National Natural Science Foundation of China(11104159)Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics Scientific,Tsinghua University,Open Research Fund Program of National Laboratory of Solid State Microstructures,Nanjing University(M25022)+2 种基金the Project Funded by the Priority,University Natural Science Research Project of Jiangsu Province(13KJB140010)Academic Program Development of Jiangsu Higher Education Institutions and the Open Research Fund of Key Laboratory of Broadband Wireless Communication and Sensor Network TechnologyNanjing University of Posts and Telecommunications,Ministry of Education(NYKL201303)
文摘We describe a high efcient entanglement concentration protocol(ECP)for multi-particle less-entangled nitrogen-vacancy(N-V)center and microtoroidal resonator system.In the ECP,we only require one pair of less-entangled state,two auxiliary N-V center in microcavities and some single photons.After the photon passing through the microcavity,by measuring the polarization of the photon,a maximally entangled W state can be obtained with some success probability.This ECP does not need to destroy the solid qubit,which makes it more feasible.Moreover,by resorting to more single photons,it can be repeated to reach a high success probability.These features make this ECP useful in current long-distance quantum communications.
基金supported by the National Basic Research Program of China (2013CB921800)the National Natural Science Foundation of China (11227901, 91021005, 10834005, 11104262) and the Chinese Academy of Sciences
文摘The measurement of the weak magnetic field in nanoscale resolution and at room temperature is always a significant topic in biological, physical, and material science. Such detection can be used to decide the characterization of the samples, such as cells, materials, and so on. Nitrogen-vacancy (NV) center in diamond has been proved to be able to detect a magnetic field with nano Tesla sensitivity and nanometer resolution at room temperature. Here we experimentally demonstrate an optimized NV center based single electron magnetometer in a commercial diamond and under a home-built optically detected magnetic resonance (ODMR) microscope. With current technology, we change the optically detected time window to get a better signal to noise ratio, and use dynamical decoupling to increase the slope of magnetic field amplitude versus fluorescence signal. By employing the 8-pulse XY-4 dynamical decoupling sequence we achieve a sensitivity of 18.9 nT (Hz)(1/2) , which is 1.7 times better than spin echo. We also propose a NV center based scanning diamond microscope for electron and nuclear spins detection as well as nanoscale magnetic resonance imaging. If it is realized, the NV center based magnetometry will have wide application in the future.
基金supported by the National Natural Science Foundation of China(61771278 and 61435007)the Joint Foundation of Ministry of Education of China(6141A02011604)supported by NSF under Grant No.PHY-1555035
文摘The spin in a rotating frame has attracted a lot of attentions recently,as it deeply relates to both fundamental physics such as pseudo-magnetic field and geometric phase,and applications such as gyroscopic sensors.However,previous studies only focused on adiabatic limit,where the rotating frequency is much smaller than the spin frequency.Here we propose to use a levitated nano-diamond with a built-in nitrogen-vacancy(NV)center to study the dynamics and the geometric phase of a rotating electron spin without adiabatic approximation.We find that the transition between the spin levels appears when the rotating frequency is comparable to the spin frequency at zero magnetic field.Then we use Floquet theory to numerically solve the spin energy spectrum,study the spin dynamics and calculate the geometric phase under a finite magnetic field,where the rotating frequency to induce resonant transition could be greatly reduced.
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 Fundamental Research Program of China(Grant No.2010CB923202)the Fundamental Research Funds for the Central Universities,Chinathe National Natural Science Foundation of China(Grant Nos.61177085,61205117,and 61377097)
文摘Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum infor- mation processing （QIP） tasks. Recently, a novel solid-state cavity quantum electrodynamics （QED） system, in which the nitrogen-vacancy （NV） center in diamond is coupled to a microtoroidal resonator （MTR）, has been proposed as a poten- tial system for hybrid quantum information and computing. By virtue of such systems, we present a scheme to realize a nonlocal N-qubit conditional phase gate directly. Our scheme employs a cavity input-output process and single-photon interference, without the use of any auxiliary entanglement pair or classical communication. Considering the currently available technologies, our scheme might be quite useful among different nodes in quantum networks for large-scaled QIP.
