We report a new design of microwave source for X-band electron paramagnetic resonance spectrometer.The microwave source is equipped with a digital automatic frequency control circuit.The parameters of the digital auto...We report a new design of microwave source for X-band electron paramagnetic resonance spectrometer.The microwave source is equipped with a digital automatic frequency control circuit.The parameters of the digital automatic frequency control circuit can be flexibly configured for different experimental conditions,such as the input powers or the quality factors of the resonator.The configurability makes the microwave source universally compatible and greatly extends its application.To demonstrate the ability of adapting to various experimental conditions,the microwave source is tested by varying the input powers and the quality factors of the resonator.A satisfactory phase noise as low as-135 d Bc/Hz at 100-k Hz offset from the center frequency is achieved,due to the use of a phase-locked dielectric resonator oscillator and a direct digital synthesizer.Continuous-wave electron paramagnetic resonance experiments are conducted to examine the performance of the microwave source.The outstanding performance shows a prospect of wide applications of the microwave source in numerous fields of science.展开更多
We present a magnetic scanning microscope equipped with a nitrogen-vacancy(NV) center scanning probe that has the ability to mechanically tune the strain of soft matter in-situ. The construction of the microscope and ...We present a magnetic scanning microscope equipped with a nitrogen-vacancy(NV) center scanning probe that has the ability to mechanically tune the strain of soft matter in-situ. The construction of the microscope and a continuous straintuning sample holder are discussed. An optically detected magnetic resonance protocol utilized in the imaging is described.In order to show the reliability of this microscope, the strain conduction is estimated with finite element simulation, and xray diffraction is required for calibration when freestanding crystal films are under consideration. A magnetic imaging result is displayed to demonstrate the nano-scale imaging capability. The microscope presented in this work is helpful in studying strain-coupled magnetic physics such as magnetic phase transition under strain and strain-tuned cycloidal orientation tilting.展开更多
Fluidics is one of the most historic subjects that are well-established over centuries on the macroscopic scale.In recent years,fluid detection using a number of micro/nano scale devices has been achieved.However,the ...Fluidics is one of the most historic subjects that are well-established over centuries on the macroscopic scale.In recent years,fluid detection using a number of micro/nano scale devices has been achieved.However,the interaction of microfluid and solid devices on micro/nano-meter scale still lacks in-depth research.We demonstrate a practical nanomechanical detector for microfluidics via a string resonator with high Q-factor,suspended over a hole.This device is placed under a jet nozzle with several microns of diameter,and the interaction between the micro-gas flow and the resonator is observed by monitoring the variation of the fundamental frequency and the quality factor.Moreover,we manage to measure the fluctuations of the micro-gas flow on the nanomechanical resonator by means of stochastic resonance.This work manifests a potential platform for detecting dynamical fluid behaviors at microscopic scale for novel fluid physics.展开更多
The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with ...The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.展开更多
Lee–Yang theory clearly demonstrates where the phase transition of many-body systems occurs and the asymptotic behavior near the phase transition using the partition function under complex parameters. The complex par...Lee–Yang theory clearly demonstrates where the phase transition of many-body systems occurs and the asymptotic behavior near the phase transition using the partition function under complex parameters. The complex parameters make the direct investigation of Lee–Yang theory in practical systems challenging. Here we construct a non-Hermitian quantum system that can correspond to the one-dimensional Ising model with imaginary parameters through the equality of partition functions. By adjusting the non-Hermitian parameter,we successfully obtain the partition function under different imaginary magnetic fields and observe the Lee–Yang zeros. We also observe the critical behavior of free energy in vicinity of Lee–Yang zero that is consistent with theoretical prediction. Our work provides a protocol to study Lee–Yang zeros of the one-dimensional Ising model using a single-qubit non-Hermitian system.展开更多
We report a new design of resonant cavity for a W-band electron paramagnetic resonance(EPR)spectrometer.An improved coupling-adjusting mechanism,which is robust,compact,and suits with both solenoid-type and split-pair...We report a new design of resonant cavity for a W-band electron paramagnetic resonance(EPR)spectrometer.An improved coupling-adjusting mechanism,which is robust,compact,and suits with both solenoid-type and split-pair magnets,is utilized on the cavity,and thus enables both continuous-wave(CW)and pulsed EPR experiments.It is achieved by a tiny metal cylinder in the iris.The coupling coefficient can be varied from 0.2 to 17.9.Furthermore,two pistons at each end of the cavity allow for adjustment of the resonant frequency.A horizontal TE_(011) geometry also makes the cavity compatible with the two frequently used types of magnets.The coupling-varying ability has been demonstrated by reflection coefficient(S_(11))measurement.CW and pulsed EPR experiments have been conducted.The performance data indicates a prospect of wide applications of the cavity in fields of physics,chemistry and biology.展开更多
Molecular qubits are promising as they can benefit from tailoring and versatile design of chemistry.It is essential to reduce the decoherence of molecular qubits caused by their interactions with the environment.Herei...Molecular qubits are promising as they can benefit from tailoring and versatile design of chemistry.It is essential to reduce the decoherence of molecular qubits caused by their interactions with the environment.Herein the dynamical decoupling(DD)technique is utilized to combat such decoherence.The coherence time for a transitionmetal complex(PPh_(4))_(2)[Cu(mnt)_(2)]is prolonged from 6.8μs to 1.4 ms.The ratio of the coherence time and the length ofπ/2 pulse,defined as the single qubit figure of merit(QM),reaches 1.4×10^(5),which is 40 times greater than what previously reported for this molecule.Our results show that molecular qubits,with milliseconds coherence time,are promising candidates for quantum information processing.展开更多
Quantum computation provides a great speedup over its classical counterpart in solving some hard problems. The advantages of quantum computation come from the coherent superposition principle of quantum mechanics. Spi...Quantum computation provides a great speedup over its classical counterpart in solving some hard problems. The advantages of quantum computation come from the coherent superposition principle of quantum mechanics. Spin system is one of the most significant candidates to realize quantum computation. In this review, we focus on the recent experimental progress related to quantum coherence and some fundamental concepts such as the uncertainty principle in the spin systems.We shall first briefly introduce the quantum description of qubit, coherence, and decoherence. Based on this picture,preserving quantum coherence and detection of weak magnetic fields are presented. We also discuss the realization of precise quantum coherent control, adiabatic quantum factorization algorithm, and two aspects of uncertainty relations.展开更多
There are some problems that quantum computers seem to be exponentially faster than classical computers, like factoring large numbers, machine learning, and simulation of quantum systems. Constructing an appropriate q...There are some problems that quantum computers seem to be exponentially faster than classical computers, like factoring large numbers, machine learning, and simulation of quantum systems. Constructing an appropriate quantum algorithm becomes more important for solving these specific problems. In principle, any quantum algorithm can recast by a quantum random walk algorithm. Although quantum random walk with a few qubits has been implemented in a variety of systems, the experimental demonstration of solid-state quantum random walk remains elusive. Here we report the experimental implementation of the quantum continuous-time random walk algorithm by a two-qubit quantum processor in a nitrogen–vacancy center in diamond. We found that quantum random walk on a circle does not converge to any stationary distribution and exhibit a reversible property. Our results represent a further investigation of quantum walking dynamics in solid spin platforms, may also lead to other practical applications by the use of quantum continuous-time random walk for quantum algorithm design and quantum coherence transport.展开更多
In marginally jammed solids confined by walls,we calculate the particle and ensemble averaged value of an order parameter,Ψ(r),as a function of the distance to the wall,r.Being a microscopic indicator of structural d...In marginally jammed solids confined by walls,we calculate the particle and ensemble averaged value of an order parameter,Ψ(r),as a function of the distance to the wall,r.Being a microscopic indicator of structural disorder and particle mobility in solids,Ψis by definition the response of the mean square particle displacement to the increase of temperature in the harmonic approximation and can be directly calculated from the normal modes of vibration of the zerotemperature solids.We find that,in confined jammed solids,Ψ(r)curves at different pressures can collapse onto the same master curve following a scaling function,indicating the criticality of the jamming transition.The scaling collapse suggests a diverging length scale and marginal instability at the jamming transition,which should be accessible to sophisticatedly designed experiments.Moreover,Ψ(r)is found to be significantly suppressed when approaching the wall and anisotropic in directions perpendicular and parallel to the wall.This finding can be applied to understand the r-dependence and anisotropy of the structural relaxation in confined supercooled liquids,providing another example of understanding or predicting behaviors of supercooled liquids from the perspective of the zero-temperature amorphous solids.展开更多
Among several dark matter candidates,bosonic ultra-light(sub-meV)dark matter is well motivated because it could couple to the Standard Model and induce new forces.Previous MICROSCOPE and E¨ot–Wash torsion experi...Among several dark matter candidates,bosonic ultra-light(sub-meV)dark matter is well motivated because it could couple to the Standard Model and induce new forces.Previous MICROSCOPE and E¨ot–Wash torsion experiments have achieved high accuracy in the sub-1 Hz region.However,at higher frequencies there is still a lack of relevant experimental research.We propose an experimental scheme based on the diamagnetic levitated micromechanical oscillator,one of the most sensitive sensors for acceleration sensitivity below the kilohertz scale.In order to improve the measurement range,we utilize a sensor whose resonance frequencyω0 could be adjusted from 0.1 Hz to 100 Hz.The limits of the coupling constant gB-Lare improved by more than 10 times compared to previous reports,and it may be possible to achieve higher accuracy by using the array of sensors in the future.展开更多
We realize a coherent transfer of mechanical excitation in a finely controlled artificial nanomechanical lattice.We also realize strong dynamic coupling between adjacent high-Q mechanical resonators,via modulated diel...We realize a coherent transfer of mechanical excitation in a finely controlled artificial nanomechanical lattice.We also realize strong dynamic coupling between adjacent high-Q mechanical resonators,via modulated dielectric force at the frequency difference between them.An excitation transfer across a lattice consisting of 7 nanobeams is observed by applying a design sequence of switching for couplings,with the final effective population reaching 0.94.This work not only demonstrates the ability to fully control an artificial lattice but also provides an efficient platform for studying complicated dynamics in one-dimensional systems.展开更多
Physical systems with gain and loss can be described by a non-Hermitian Hamiltonian,which is degenerated at the exceptional points(EPs).Many new and unexpected features have been explored in the non-Hermitian systems ...Physical systems with gain and loss can be described by a non-Hermitian Hamiltonian,which is degenerated at the exceptional points(EPs).Many new and unexpected features have been explored in the non-Hermitian systems with a great deal of recent interest.One of the most fascinating features is that chiral state conversion appears when one EP is encircled dynamically.Here,we propose an easy-controllable levitated microparticle system that carries a pair of EPs and realize slow evolution of the Hamiltonian along loops in the parameter plane.Utilizing the controllable rotation angle,gain and loss coefficients,we can control the structure,size and location of the loops in situ.We demonstrate that,under the joint action of topological structure of energy surfaces and nonadiabatic transitions,the chiral behavior emerges both along a loop encircling an EP and even along a straight path away from the EP.This work broadens the range of parameter space for the chiral state conversion,and proposes a useful platform to explore the interesting properties of exceptional points physics.展开更多
Recently,magnetism in two-dimensional(2 D)van der Waals(vd W)materials has attracted wide interests.It is anticipated that these materials will stimulate discovery of new physical phenomena and novel applications.The ...Recently,magnetism in two-dimensional(2 D)van der Waals(vd W)materials has attracted wide interests.It is anticipated that these materials will stimulate discovery of new physical phenomena and novel applications.The capability to quantitatively measure the magnetism of 2 D magnetic vd W materials is essential to understand these materials.Here we report on quantitative measurements of ferromagnetic-to-paramagnetic phase transition of an atomically thin(down to 11 nm)vd W magnet,namely Cr Br_(3),with a Curie point of 37.5 K.This experiment demonstrates that surface magnetism can be quantitatively investigated,which is useful for a wide variety of potential applications.展开更多
Recently,a study reported on the use of in situ electron paramagnetic resonance(EPR)spectroscopy to investigate two consecutive single-electron processes in polyimide and directly diagnose typical electrochemical reac...Recently,a study reported on the use of in situ electron paramagnetic resonance(EPR)spectroscopy to investigate two consecutive single-electron processes in polyimide and directly diagnose typical electrochemical reactions of carbonyl-based organic electrode in Li-ion batteries(LIBs).This research offers the important experimental clue for studying specific electron conversion routes of multi-electron transfer reactions in LIB materials[1].展开更多
Magnetic fields are ubiquitous,and precise measurements of them can serve as powerful tools for deep understanding and accurate detection across multiple disciplines,including physics,biology,and chemistry[1].For inst...Magnetic fields are ubiquitous,and precise measurements of them can serve as powerful tools for deep understanding and accurate detection across multiple disciplines,including physics,biology,and chemistry[1].For instance,by measuring the magnetic fields within the human heart and brain,the medical community could obtain accurate disease diagnoses.展开更多
Non-Hermitian Hamiltonians are widely used in describing open systems with gain and loss,among which a key phenomenon is the non-Hermitian skin effect.Here we report an experimental scheme to realize a twodimensional(...Non-Hermitian Hamiltonians are widely used in describing open systems with gain and loss,among which a key phenomenon is the non-Hermitian skin effect.Here we report an experimental scheme to realize a twodimensional(2D)discrete-time quantum walk with non-Hermitian skin effect in a single trapped ion.It is shown that the coin and 2D walker states can be labeled in the spin of the ion and the coherent-state lattice of the ion motion,respectively.We numerically observe a directional bulk flow,whose orientations are controlled by dissipative parameters,showing the emergence of the non-Hermitian skin effect.We then discuss an experimental implementation of our scheme in a laser-controlled trapped Ca^(+)ion.Our experimental proposal may be applicable to research of dissipative quantum walk systems and may be able to generalize to other platforms,such as superconducting circuits and atoms in cavity.展开更多
Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 H.To achieve suc...Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 H.To achieve such a polarization transfer,the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating frame.In this work,we analyze the spin dynamics of the Hartmann-Hahn CP(HHCP)utilizing the 1 H spin-locking,and the dipolar-order CP(DOCP)having the 1 H adiabatic demagnetization.We further propose an adiabatic demagnetization CP(ADCP)where a constant radio-frequency pulse is applied on the S spin while 1 H is adiabatically demagnetized.Our analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1 H to S spins.In addition,the dipolar ordered state generated during the 1 H demagnetization process could also be converted into the observable S polarization through DOCP,further enhancing the polarized signals.It is shown by both static and magic-angle-spinning(MAS)NMR experiments that ADCP has dramatically broadened the CP matching condition over the other CP schemes.Various samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.展开更多
As a complementary analysis tool to conventional high-field nuclear magnetic resonance(NMR),zero-to ultralow-field(ZULF)NMR detects nuclear magnetization signals in the sub-microtesla regime.Spin-exchange relaxation-f...As a complementary analysis tool to conventional high-field nuclear magnetic resonance(NMR),zero-to ultralow-field(ZULF)NMR detects nuclear magnetization signals in the sub-microtesla regime.Spin-exchange relaxation-free(SERF)atomic magnetometers provide a new generation of sensitive detectors for ZULF NMR.Owing to features such as low cost,high resolution,and portability,ZULF NMR has recently attracted considerable attention in chemistry,biology,medicine,and tests of fundamental physics.This review describes the basic principles,methodology,and recent experimental and theoretical development of ZULF NMR as well as its applications in spectroscopy,quantum control,imaging,NMR-based quantum devices,and tests of fundamental physics.The future prospects of ZULF NMR are also discussed.展开更多
A high performance fast-Fourier-transform (FFT) spectrum analyzer, which is developed for measure spin noise spectrums, is presented in this paper. The analyzer is implemented with a field-programmable-gate-arrays (FP...A high performance fast-Fourier-transform (FFT) spectrum analyzer, which is developed for measure spin noise spectrums, is presented in this paper. The analyzer is implemented with a field-programmable-gate-arrays (FPGA) chip for data and command management. An analog-to-digital-convertor chip is integrated for analog signal acquisition. In order to meet the various requirements of measuring different types of spin noise spectrums, multiple operating modes are designed and realized using the reprogrammable FPGA logic resources. The FFT function is fully managed by the programmable resource inside the FPGA chip. A 1 GSa/s sampling rate and a 100 percent data coverage ratio with non-dead-time are obtained. 30534 FFT spectrums can be acquired per second, and the spectrums can be on-board accumulated and averaged. Digital filters, multi-stage reconfigurable data reconstruction modules, and frequency down conversion modules are also implemented in the FPGA to provide flexible real-time data processing capacity, thus the noise floor and signals aliasing can be suppressed effectively. An efficiency comparison between the FPGA-based FFT spectrum analyzer and the software-based FFT is demonstrated, and the high performance FFT spectrum analyzer has a significant advantage in obtaining high resolution spin noise spectrums with enhanced efficiency.展开更多
基金Project supported by the Chinese Academy of Sciences(Grant Nos.XDC07000000 and GJJSTD20200001)Hefei Comprehensive National Science CenterYouth Innovation Promotion Association of Chinese Academy of Sciences for the support。
文摘We report a new design of microwave source for X-band electron paramagnetic resonance spectrometer.The microwave source is equipped with a digital automatic frequency control circuit.The parameters of the digital automatic frequency control circuit can be flexibly configured for different experimental conditions,such as the input powers or the quality factors of the resonator.The configurability makes the microwave source universally compatible and greatly extends its application.To demonstrate the ability of adapting to various experimental conditions,the microwave source is tested by varying the input powers and the quality factors of the resonator.A satisfactory phase noise as low as-135 d Bc/Hz at 100-k Hz offset from the center frequency is achieved,due to the use of a phase-locked dielectric resonator oscillator and a direct digital synthesizer.Continuous-wave electron paramagnetic resonance experiments are conducted to examine the performance of the microwave source.The outstanding performance shows a prospect of wide applications of the microwave source in numerous fields of science.
基金the National Natural Science Foundation of China (Grant Nos. 81788101, T2125011, 11861161004, and 12104447)the National Key R&D Program of China (Grant No. 2018YFA0306600)+5 种基金the Chinese Academy of Sciences (Grant Nos. XDC07000000, GJJSTD20200001,QYZDY-SSW-SLH004,Y201984, and YSBR-068)Innovation Program for Quantum Science and Technology (Grant Nos. 2021ZD0303204 and 2021ZD0302200)the Anhui Initiative in Quantum Information Technologies (Grant No. AHY050000)Hefei Comprehensive National Science CenterChina Postdoctoral Science Foundation (Grant No. 2020M671858)the Fundamental Research Funds for the Central Universities。
文摘We present a magnetic scanning microscope equipped with a nitrogen-vacancy(NV) center scanning probe that has the ability to mechanically tune the strain of soft matter in-situ. The construction of the microscope and a continuous straintuning sample holder are discussed. An optically detected magnetic resonance protocol utilized in the imaging is described.In order to show the reliability of this microscope, the strain conduction is estimated with finite element simulation, and xray diffraction is required for calibration when freestanding crystal films are under consideration. A magnetic imaging result is displayed to demonstrate the nano-scale imaging capability. The microscope presented in this work is helpful in studying strain-coupled magnetic physics such as magnetic phase transition under strain and strain-tuned cycloidal orientation tilting.
基金Supported by the National Key R&D Program of China(Grant No.2018YFA0306600)the Chinese Academy of Sciences(Grant Nos.GJJSTD20170001 and QYZDY-SSW-SLH004)Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000).
文摘Fluidics is one of the most historic subjects that are well-established over centuries on the macroscopic scale.In recent years,fluid detection using a number of micro/nano scale devices has been achieved.However,the interaction of microfluid and solid devices on micro/nano-meter scale still lacks in-depth research.We demonstrate a practical nanomechanical detector for microfluidics via a string resonator with high Q-factor,suspended over a hole.This device is placed under a jet nozzle with several microns of diameter,and the interaction between the micro-gas flow and the resonator is observed by monitoring the variation of the fundamental frequency and the quality factor.Moreover,we manage to measure the fluctuations of the micro-gas flow on the nanomechanical resonator by means of stochastic resonance.This work manifests a potential platform for detecting dynamical fluid behaviors at microscopic scale for novel fluid physics.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFB3202800 and 2023YF0718400)Chinese Academy of Sciences(Grant No.ZDZBGCH2021002)+2 种基金Chinese Academy of Sciences(Grant No.GJJSTD20200001)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303204)Anhui Initiative in Quantum Information Technologies,USTC Tang Scholar,and the Fundamental Research Funds for the Central Universities.
文摘The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.
基金supported by the National Key R&D Program of China (Grant No. 2021YFB3202800)the National Natural Science Foundation of China (Grant No. 12174373)+2 种基金the Chinese Academy of Sciences (Grant No. GJJSTD20200001)the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302200)Anhui Initiative in Quantum Information Technologies (Grant No. AHY050000)。
文摘Lee–Yang theory clearly demonstrates where the phase transition of many-body systems occurs and the asymptotic behavior near the phase transition using the partition function under complex parameters. The complex parameters make the direct investigation of Lee–Yang theory in practical systems challenging. Here we construct a non-Hermitian quantum system that can correspond to the one-dimensional Ising model with imaginary parameters through the equality of partition functions. By adjusting the non-Hermitian parameter,we successfully obtain the partition function under different imaginary magnetic fields and observe the Lee–Yang zeros. We also observe the critical behavior of free energy in vicinity of Lee–Yang zero that is consistent with theoretical prediction. Our work provides a protocol to study Lee–Yang zeros of the one-dimensional Ising model using a single-qubit non-Hermitian system.
基金Project supported by the Chinese Academy of Sciences(Grant Nos.XDC07000000 and GJJSTD20200001)the Youth Innovation Promotion Association of Chinese Academy of Sciences for the support。
文摘We report a new design of resonant cavity for a W-band electron paramagnetic resonance(EPR)spectrometer.An improved coupling-adjusting mechanism,which is robust,compact,and suits with both solenoid-type and split-pair magnets,is utilized on the cavity,and thus enables both continuous-wave(CW)and pulsed EPR experiments.It is achieved by a tiny metal cylinder in the iris.The coupling coefficient can be varied from 0.2 to 17.9.Furthermore,two pistons at each end of the cavity allow for adjustment of the resonant frequency.A horizontal TE_(011) geometry also makes the cavity compatible with the two frequently used types of magnets.The coupling-varying ability has been demonstrated by reflection coefficient(S_(11))measurement.CW and pulsed EPR experiments have been conducted.The performance data indicates a prospect of wide applications of the cavity in fields of physics,chemistry and biology.
基金Supported by the National Key R&D Program of China(Grant Nos.2018YFA0306600 and 2016YFB0501603)the Chinese Academy of Sciences(Grant Nos.GJJSTD20170001,QYZDY-SSW-SLH004,and QYZDB-SSW-SLH005)+2 种基金Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000)the Youth Innovation Promotion Association of Chinese Academy of Sciences for their supportthe support from Wuhan National High Magnetic Field Center(Grant No.2015KF06)。
文摘Molecular qubits are promising as they can benefit from tailoring and versatile design of chemistry.It is essential to reduce the decoherence of molecular qubits caused by their interactions with the environment.Herein the dynamical decoupling(DD)technique is utilized to combat such decoherence.The coherence time for a transitionmetal complex(PPh_(4))_(2)[Cu(mnt)_(2)]is prolonged from 6.8μs to 1.4 ms.The ratio of the coherence time and the length ofπ/2 pulse,defined as the single qubit figure of merit(QM),reaches 1.4×10^(5),which is 40 times greater than what previously reported for this molecule.Our results show that molecular qubits,with milliseconds coherence time,are promising candidates for quantum information processing.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0306600 and 2016YFB0501603)the Fund from the Chinese Academy of Sciences(Grant Nos.GJJSTD20170001,QYZDY-SSW-SLH004,and QYZDB-SSW-SLH005)the Program from Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY050000)
文摘Quantum computation provides a great speedup over its classical counterpart in solving some hard problems. The advantages of quantum computation come from the coherent superposition principle of quantum mechanics. Spin system is one of the most significant candidates to realize quantum computation. In this review, we focus on the recent experimental progress related to quantum coherence and some fundamental concepts such as the uncertainty principle in the spin systems.We shall first briefly introduce the quantum description of qubit, coherence, and decoherence. Based on this picture,preserving quantum coherence and detection of weak magnetic fields are presented. We also discuss the realization of precise quantum coherent control, adiabatic quantum factorization algorithm, and two aspects of uncertainty relations.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0306600 and 2016YFB0501603)the National Natural Science Foundation of China(Grant No.11761131011)+2 种基金the Fund from the Chinese Academy of Sciences(Grant Nos.GJJSTD20170001,QYZDYSSW-SLH004,and QYZDB-SSW-SLH005)the Anhui Initiative Fund in Quantum Information Technologies,China(Grant No.AHY050000)the Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘There are some problems that quantum computers seem to be exponentially faster than classical computers, like factoring large numbers, machine learning, and simulation of quantum systems. Constructing an appropriate quantum algorithm becomes more important for solving these specific problems. In principle, any quantum algorithm can recast by a quantum random walk algorithm. Although quantum random walk with a few qubits has been implemented in a variety of systems, the experimental demonstration of solid-state quantum random walk remains elusive. Here we report the experimental implementation of the quantum continuous-time random walk algorithm by a two-qubit quantum processor in a nitrogen–vacancy center in diamond. We found that quantum random walk on a circle does not converge to any stationary distribution and exhibit a reversible property. Our results represent a further investigation of quantum walking dynamics in solid spin platforms, may also lead to other practical applications by the use of quantum continuous-time random walk for quantum algorithm design and quantum coherence transport.
基金Project supported by the National Natural Science Foundation of China(Grant No.11734014)。
文摘In marginally jammed solids confined by walls,we calculate the particle and ensemble averaged value of an order parameter,Ψ(r),as a function of the distance to the wall,r.Being a microscopic indicator of structural disorder and particle mobility in solids,Ψis by definition the response of the mean square particle displacement to the increase of temperature in the harmonic approximation and can be directly calculated from the normal modes of vibration of the zerotemperature solids.We find that,in confined jammed solids,Ψ(r)curves at different pressures can collapse onto the same master curve following a scaling function,indicating the criticality of the jamming transition.The scaling collapse suggests a diverging length scale and marginal instability at the jamming transition,which should be accessible to sophisticatedly designed experiments.Moreover,Ψ(r)is found to be significantly suppressed when approaching the wall and anisotropic in directions perpendicular and parallel to the wall.This finding can be applied to understand the r-dependence and anisotropy of the structural relaxation in confined supercooled liquids,providing another example of understanding or predicting behaviors of supercooled liquids from the perspective of the zero-temperature amorphous solids.
基金the National Natural Science Foundation of China(Grant Nos.12205291,12075115,12075116,11890702,and 12150011)the Fundamental Research Funds for the Central UniversitiesAnhui Provincial Natural Science Foundation(Grant No.2208085QA16)。
文摘Among several dark matter candidates,bosonic ultra-light(sub-meV)dark matter is well motivated because it could couple to the Standard Model and induce new forces.Previous MICROSCOPE and E¨ot–Wash torsion experiments have achieved high accuracy in the sub-1 Hz region.However,at higher frequencies there is still a lack of relevant experimental research.We propose an experimental scheme based on the diamagnetic levitated micromechanical oscillator,one of the most sensitive sensors for acceleration sensitivity below the kilohertz scale.In order to improve the measurement range,we utilize a sensor whose resonance frequencyω0 could be adjusted from 0.1 Hz to 100 Hz.The limits of the coupling constant gB-Lare improved by more than 10 times compared to previous reports,and it may be possible to achieve higher accuracy by using the array of sensors in the future.
文摘We realize a coherent transfer of mechanical excitation in a finely controlled artificial nanomechanical lattice.We also realize strong dynamic coupling between adjacent high-Q mechanical resonators,via modulated dielectric force at the frequency difference between them.An excitation transfer across a lattice consisting of 7 nanobeams is observed by applying a design sequence of switching for couplings,with the final effective population reaching 0.94.This work not only demonstrates the ability to fully control an artificial lattice but also provides an efficient platform for studying complicated dynamics in one-dimensional systems.
基金Supported by the Fundamental Research Funds for the Central Universities(Grant No.WK2030000032)the National Key R&D Program of China(Grant No.2018YFA0306600)+1 种基金the CAS(Grant Nos.GJJSTD20170001 and QYZDY-SSW-SLH004)Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000).
文摘Physical systems with gain and loss can be described by a non-Hermitian Hamiltonian,which is degenerated at the exceptional points(EPs).Many new and unexpected features have been explored in the non-Hermitian systems with a great deal of recent interest.One of the most fascinating features is that chiral state conversion appears when one EP is encircled dynamically.Here,we propose an easy-controllable levitated microparticle system that carries a pair of EPs and realize slow evolution of the Hamiltonian along loops in the parameter plane.Utilizing the controllable rotation angle,gain and loss coefficients,we can control the structure,size and location of the loops in situ.We demonstrate that,under the joint action of topological structure of energy surfaces and nonadiabatic transitions,the chiral behavior emerges both along a loop encircling an EP and even along a straight path away from the EP.This work broadens the range of parameter space for the chiral state conversion,and proposes a useful platform to explore the interesting properties of exceptional points physics.
基金supported by the National Natural Science Foundation of China(Grant Nos.81788101,T2125011,and 11874338)the National Key R&D Program of China(Grant No.2018YFA0306600)+2 种基金Chinese Academy of Sciences(Grants Nos.XDC07000000,GJJSTD20200001,QYZDY-SSW-SLH004,and ZDZBGCH2021002)Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000)Fundamental Research Funds for the Central Universities。
文摘Recently,magnetism in two-dimensional(2 D)van der Waals(vd W)materials has attracted wide interests.It is anticipated that these materials will stimulate discovery of new physical phenomena and novel applications.The capability to quantitatively measure the magnetism of 2 D magnetic vd W materials is essential to understand these materials.Here we report on quantitative measurements of ferromagnetic-to-paramagnetic phase transition of an atomically thin(down to 11 nm)vd W magnet,namely Cr Br_(3),with a Curie point of 37.5 K.This experiment demonstrates that surface magnetism can be quantitatively investigated,which is useful for a wide variety of potential applications.
文摘Recently,a study reported on the use of in situ electron paramagnetic resonance(EPR)spectroscopy to investigate two consecutive single-electron processes in polyimide and directly diagnose typical electrochemical reactions of carbonyl-based organic electrode in Li-ion batteries(LIBs).This research offers the important experimental clue for studying specific electron conversion routes of multi-electron transfer reactions in LIB materials[1].
文摘Magnetic fields are ubiquitous,and precise measurements of them can serve as powerful tools for deep understanding and accurate detection across multiple disciplines,including physics,biology,and chemistry[1].For instance,by measuring the magnetic fields within the human heart and brain,the medical community could obtain accurate disease diagnoses.
基金supported by the National Natural Science Foundation of China(Grant Nos.92165206 and 11974330)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301603)the Fundamental Research Funds for the Central Universities。
文摘Non-Hermitian Hamiltonians are widely used in describing open systems with gain and loss,among which a key phenomenon is the non-Hermitian skin effect.Here we report an experimental scheme to realize a twodimensional(2D)discrete-time quantum walk with non-Hermitian skin effect in a single trapped ion.It is shown that the coin and 2D walker states can be labeled in the spin of the ion and the coherent-state lattice of the ion motion,respectively.We numerically observe a directional bulk flow,whose orientations are controlled by dissipative parameters,showing the emergence of the non-Hermitian skin effect.We then discuss an experimental implementation of our scheme in a laser-controlled trapped Ca^(+)ion.Our experimental proposal may be applicable to research of dissipative quantum walk systems and may be able to generalize to other platforms,such as superconducting circuits and atoms in cavity.
基金supported by the NSF Cooperative Agreement DMR-1644779the State of Florida.X.H.P.acknowledges the supports from the National Key R&D Program of China(Grants No.2018YFA0306600)+1 种基金the National Science Foundation of China(Grants No.11927811,12150014)Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000).
文摘Cross polarization(CP)is a widely used solid-state nuclear magnetic resonance(NMR)technique for enhancing the polarization of dilute S spins from much larger polarization of abundant I spins such as 1 H.To achieve such a polarization transfer,the I spin should either be spin-locked or be converted to the dipolar ordered state through adiabatic demagnetization in the rotating frame.In this work,we analyze the spin dynamics of the Hartmann-Hahn CP(HHCP)utilizing the 1 H spin-locking,and the dipolar-order CP(DOCP)having the 1 H adiabatic demagnetization.We further propose an adiabatic demagnetization CP(ADCP)where a constant radio-frequency pulse is applied on the S spin while 1 H is adiabatically demagnetized.Our analyses indicate that ADCP utilizes the adiabatic passage to effectively achieve the polarization transfer from the 1 H to S spins.In addition,the dipolar ordered state generated during the 1 H demagnetization process could also be converted into the observable S polarization through DOCP,further enhancing the polarized signals.It is shown by both static and magic-angle-spinning(MAS)NMR experiments that ADCP has dramatically broadened the CP matching condition over the other CP schemes.Various samples have been used to demonstrate the polarization transfer efficiency of this newly proposed ADCP scheme.
基金This work was supported by National Key Research and Development Program of China(Grant no.2018YFA0306600)National Natural Science Foun-dation of China(Grants nos.11661161018,11927811)+1 种基金Anhui Initia-tive in Quantum Information Technologies(Grant No.AHY050000)USTC Research Funds of the Double First-Class Initiative(Grant no.YD3540002002).
文摘As a complementary analysis tool to conventional high-field nuclear magnetic resonance(NMR),zero-to ultralow-field(ZULF)NMR detects nuclear magnetization signals in the sub-microtesla regime.Spin-exchange relaxation-free(SERF)atomic magnetometers provide a new generation of sensitive detectors for ZULF NMR.Owing to features such as low cost,high resolution,and portability,ZULF NMR has recently attracted considerable attention in chemistry,biology,medicine,and tests of fundamental physics.This review describes the basic principles,methodology,and recent experimental and theoretical development of ZULF NMR as well as its applications in spectroscopy,quantum control,imaging,NMR-based quantum devices,and tests of fundamental physics.The future prospects of ZULF NMR are also discussed.
基金Project supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDC07020200)the National Key R&D Program of China(Grant Nos.2018YFA0306600 and 2016YFB0501603)+3 种基金the National Natural Science Foundation of China(Grant No.11927811)the Chinese Academy of Sciences(Grants Nos.GJJSTD20170001 and QYZDY-SSW-SLH004)Anhui Initiative in Quantum Information Technologies,China(Grant No.AHY050000)the Fundamental Research Funds for the Central Universities,China.
文摘A high performance fast-Fourier-transform (FFT) spectrum analyzer, which is developed for measure spin noise spectrums, is presented in this paper. The analyzer is implemented with a field-programmable-gate-arrays (FPGA) chip for data and command management. An analog-to-digital-convertor chip is integrated for analog signal acquisition. In order to meet the various requirements of measuring different types of spin noise spectrums, multiple operating modes are designed and realized using the reprogrammable FPGA logic resources. The FFT function is fully managed by the programmable resource inside the FPGA chip. A 1 GSa/s sampling rate and a 100 percent data coverage ratio with non-dead-time are obtained. 30534 FFT spectrums can be acquired per second, and the spectrums can be on-board accumulated and averaged. Digital filters, multi-stage reconfigurable data reconstruction modules, and frequency down conversion modules are also implemented in the FPGA to provide flexible real-time data processing capacity, thus the noise floor and signals aliasing can be suppressed effectively. An efficiency comparison between the FPGA-based FFT spectrum analyzer and the software-based FFT is demonstrated, and the high performance FFT spectrum analyzer has a significant advantage in obtaining high resolution spin noise spectrums with enhanced efficiency.
