The atomic-vapor cell is a vital component for Rydberg atomic microwave sensors,and impacts on overall capability of Rydberg sensors.However,the conventional analysis approach on effect of vapor-cell length contains t...The atomic-vapor cell is a vital component for Rydberg atomic microwave sensors,and impacts on overall capability of Rydberg sensors.However,the conventional analysis approach on effect of vapor-cell length contains two implicit assumptions,that is,the same atomic population density and buffer gas pressure,which make it unable to accurately capture actual response about effect of Rydberg-atom-based sensor performance on different Rydberg atom populations.Here,utilizing a stepped cesium atomic-vapor cell with five different dimensions at the same atomic population density and buffer gas pressure,the height and full width at half maximum of electromagnetically induced transparency(EIT)signal,and the sensitivity of the atomic superheterodyne sensor are comprehensively investigated under conditions of the same Rabi frequencies(saturated laser power).It is identified that EIT signal height is proportional to the cell length,full width at half maximum and sensitivity grow with the increment of cell length to a certain extent.Employing the coherent integration signal theory and atomic linear expansion coefficient method,theoretical analysis of the EIT height and sensitivity are further investigated.The results could shed new light on understanding and design of ultrahigh-sensitivity Rydberg atomic microwave sensors and find promising applications in quantum measurement,communication,and imaging.展开更多
Strongly-interacting Rydberg atomic ensembles have shown intense collective excitation effects due to the inclusion of single Rydberg excitation shared by multiple atoms in the ensemble.In this paper we investigate a ...Strongly-interacting Rydberg atomic ensembles have shown intense collective excitation effects due to the inclusion of single Rydberg excitation shared by multiple atoms in the ensemble.In this paper we investigate a counter-intuitive Rydberg excitation facilitation with a strongly-interacting atomic ensemble in the strong probe-field regime,which is enabled by the role of a control atom nearby.Differing from the case of a single ensemble,we show that,the control atom's excitation adds to a second two-photon transition onto the doubly-excited Rydberg state,arising an excitation facilitation for the ensemble atoms.Our numerical studies depending on the method of quantum Monte Carlo wave function,exhibit the observation constraints of this excitation facilitation effect under practical experimental conditions.The results obtained can provide a flexible control for the excitation of Rydberg atomic ensembles and participate further uses in developing mesoscopic Rydberg gates for multiqubit quantum computation.展开更多
We demonstrate a simple method to measure electric field intensity by using doublet electromagnetically induced transparency(EIT) spectra of cold Rb Rydberg atoms, where the frequency of the coupling laser does not ne...We demonstrate a simple method to measure electric field intensity by using doublet electromagnetically induced transparency(EIT) spectra of cold Rb Rydberg atoms, where the frequency of the coupling laser does not need to be locked. Based on the Stark splitting of the Rb Rydberg state, 10D_(3/2), under electric fields and the corresponding calculated polarizabilities, the real electric field intensity is calculated using the difference in radio-frequency diffraction between two acousto-optic modulators, which acts as a frequency criterion that allows us to measure the electrical field without locking the coupling laser. The value measured by this simple method shows a good agreement with our previous work [Opt.Express 29 1558(2021)] where the frequency of the coupling laser needs to be locked with an additional EIT spectrum based on atom vapor and a proportional–integral–differential feedback circuit. Our presented method can also be extended to the measurement of electric field based on hot Rydberg atom vapor, which has application in industry.展开更多
We present a scheme for dissipatively preparing bipartite Knill–Laflamme–Milburn(KLM)entangled state in a neutral atom system,where the spontaneous emission of excited Rydberg states,combined with the coherent popul...We present a scheme for dissipatively preparing bipartite Knill–Laflamme–Milburn(KLM)entangled state in a neutral atom system,where the spontaneous emission of excited Rydberg states,combined with the coherent population trapping,is actively exploited to engineer a steady KLM state from an arbitrary initial state.Instead of commonly used antiblockade dynamics of two Rydberg atoms,we particularly utilize the Rydberg–Rydberg interaction as the pumping source to drive the undesired states so that it is unnecessary to satisfy a certain relation with laser detuning.The numerical simulation of the master equation signifies that both the fidelity and the purity above 98%is available with the current feasible parameters,and the corresponding steady-state fidelity is robust to the variations of the dynamical parameters.展开更多
Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago.Recent experimental and theoretical progresses have shined exciting light on this avenue.In this concise review,we...Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago.Recent experimental and theoretical progresses have shined exciting light on this avenue.In this concise review,we will briefly introduce the basics of Rydberg atoms and their recent applications in associated areas of neutral atom quantum computation and simulation.We shall also include related discussions on quantum optics with Rydberg atomic ensembles,which are increasingly used to explore quantum computation and quantum simulation with photons.展开更多
Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the pres...Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the presence of a local RF(LO RF)field.In this study,we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation(AM)of the LO RF field;that is,the phase of the SIG RF field is related to both the amplitude and phase of the beat signal.When the AM frequency of the LO RF field is the same as the frequency of the beat signal,the beat signal will further interfere with the AM of the LO RF field inside the atom,and then the amplitude of the beat signal is related to the phase of the SIG RF field.The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 toπ/2 when the phase of the AM is set with a differenceπ/4 from the phase of the LO RF field.The minimum phase resolution can be as small as 0.6°by optimizing the experimental conditions according to a simple theoretical model.This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.展开更多
Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6 P3/2 state when cooling lasers of the magneto-optical trap are modula...Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6 P3/2 state when cooling lasers of the magneto-optical trap are modulated.The experiment results show that the signal to noise ratio has been improved by 32.64 dB when the modulation depth(converted to laser frequency)and frequency are optimized to 4 MHz and 6 kHz,respectively.This technique enables us to perform a highly sensitive non-destructive detection of Rydberg atoms.展开更多
Rydberg atoms have been widely investigated due to their large size,long radiative lifetime,huge polarizability and strong dipole-dipole interactions.The position information of Rydberg atoms provides more possibiliti...Rydberg atoms have been widely investigated due to their large size,long radiative lifetime,huge polarizability and strong dipole-dipole interactions.The position information of Rydberg atoms provides more possibilities for quantum optics research,which can be obtained under the localization method.We study the behavior of three-dimensional(3D)Rydberg atom localization in a four-level configuration with the measurement of the spatial optical absorption.The atomic localization precision depends strongly on the detuning and Rabi frequency of the involved laser fields.A 100%probability of finding the Rydberg atom at a specific 3D position is achieved with precision of~0.031λ.This work demonstrates the possibility for achieving the 3D atom localization of the Rydberg atom in the experiment.展开更多
We study the ionization of helium Rydberg atoms in an electric field above the classical ionization threshold within the semiclassical theory.By introducing a fractal approach to describe the chaotic dynamical behavio...We study the ionization of helium Rydberg atoms in an electric field above the classical ionization threshold within the semiclassical theory.By introducing a fractal approach to describe the chaotic dynamical behavior of the ionization,we identify the fractal self-similarity structure of the escape time versus the distribution of the initial launch angles of electrons,and find that the self-similarity region shifts toward larger initial launch angles with a decrease in the scaled energy.We connect the fractal structure of the escape time plot to the escape dynamics of ionized electrons.Of particular note is that the fractal dimensions are sensitively controlled by the scaled energy and magnetic field,and exhibit excellent agreement with the chaotic extent of the ionization systems for both helium and hydrogen Rydberg atoms.It is shown that,besides the electric and magnetic fields,core scattering is a primary factor in the fractal dynamics.展开更多
We study the steady optical response of a square lattice in which all trapped atoms are driven by a probe and a coupling fields into the ladder configuration of electromagnetically induced transparency(EIT).It turns o...We study the steady optical response of a square lattice in which all trapped atoms are driven by a probe and a coupling fields into the ladder configuration of electromagnetically induced transparency(EIT).It turns out to be a manybody problem in the presence of van der Waals(vd W)interaction among atoms in the upmost Rydberg state,so Monte Carlo(MC)calculation based on density matrix equations have been done after introducing a sufficiently large cut-off radius.It is found that the absorption and dispersion of EIT spectra depends critically on a few key parameters like lattice dimension,unitary vd W shift,probe Rabi frequency,and coupling detuning.Through modulating these parameters,it is viable to change symmetries of the absorption and dispersion spectra and control on demand depth and position of the transparency window.Our MC calculation is expected to be instructive in understanding many-body quantum coherence effects and in manipulating non-equilibrium quantum phenomena by utilizing vd W interactions of Rydberg atoms.展开更多
The geometry effect of a vapor cell on the metrology of a microwave electric field is investigated. Based on the splitting of the electromagnetically induced transparency spectra of cesium Rydberg atoms in a vapor cel...The geometry effect of a vapor cell on the metrology of a microwave electric field is investigated. Based on the splitting of the electromagnetically induced transparency spectra of cesium Rydberg atoms in a vapor cell, high-resolution spatial distribution of the microwave electric field strength is achieved for both a cubic cell and a cylinder cell. The spatial distribution of the microwave field strength in two dimensions is measured with sub-wavelength resolution. The experimental results show that the shape of a vapor cell has a significant influence on the abnormal spatial distribution because of the Fabry–Pérot effect inside a vapor cell. A theoretical simulation is obtained for different vapor cell wall thicknesses and shows that a restricted wall thickness results in a measurement fluctuation smaller than 3% at the center of the vapor cell.展开更多
We present a new method for computing the recurrence spectra of n≈40,m=0 lithium Rydberg atoms in strong parallel external electric and magnetic fields.This method is based on an extended closed-orbit theory allowing...We present a new method for computing the recurrence spectra of n≈40,m=0 lithium Rydberg atoms in strong parallel external electric and magnetic fields.This method is based on an extended closed-orbit theory allowing the computation of the scattering of the electron by the ionic core.We pay particular attention to the scaling properties,which are extremely important for understanding the correspondence between classical and quantum mechanics.The spectra with a constant scaled electric field F=0.01 and a scaled energy ε=-0.03 are recorded and compared with those of hydrogen obtained by the standard closed-orbit theory.The result shows that the additional strong resonance structures can be interpreted in terms of the core-scattered classical closed orbits.展开更多
We present nonlinear spectra of four-level ladder cesium atoms employing 6 S1/2→6 P3/2→7 S1/2→30 P3/2 scheme of a room temperature vapor cell.A coupling laser drives Rydberg transition,a dressing laser couples two ...We present nonlinear spectra of four-level ladder cesium atoms employing 6 S1/2→6 P3/2→7 S1/2→30 P3/2 scheme of a room temperature vapor cell.A coupling laser drives Rydberg transition,a dressing laser couples two intermediate levels,and a probe laser optically probes the nonlinear spectra via electromagnetically induced transparency(EIT).Nonlinear spectra are detected as a function of coupling laser frequency.The observed spectra exhibit an enhanced absorption(EA) signal at coupling laser resonance to Rydberg transition and enhanced transmission(ET) signals at detunings to the transition.We define the enhanced absorption(transmission) strength,HEA(HET),and distance between two ET peaks,γET,to describe the spectral feature of the four-level atoms.The enhanced absorption signal HEA is found to have a maximum value when we vary the dressing laser Rabi frequency Ωd,corresponding Rabi frequency is defined as a separatrix point,ΩdSe.The values of ΩdSe and further η=ΩdSe/Ωc are found to depend on the probe and coupling Rabi frequency but not the atomic density.Based on ΩdSe,the spectra can be separated into two regimes,weak and strong dressing ranges,Ωd≤ΩdSe and Ωd≥QdSe,respectively.The spectroscopies display different features at these two regimes.A four-level theoretical model is developed that agrees well with the experimental results in terms of the probe-beam absorption behavior of Rabi frequency-dependent dressed states.展开更多
Motivated by experimental advances that the collective excitation of two Rydberg atoms was observed, we provide an elaborate theoretical study for the dynamical behavior of two-atom Rabi oscillations. In the large-int...Motivated by experimental advances that the collective excitation of two Rydberg atoms was observed, we provide an elaborate theoretical study for the dynamical behavior of two-atom Rabi oscillations. In the large-intermediate-detuning case, the two-photon Rabi oscillation is found to be significantly affected by the strength of the interatomic van der Waals interaction. With a careful comparison of the exact numbers and values of the oscillation frequency, we propose a new way to determine the strength of excitation blockade, agreeing well with the previous universal criterion for full, partial, and no blockade regions. In the small-intermediate-detuning case, we find a blockade-like effect, but the collective enhancement factor is smaller than ^(1/2) due to the quantum interference of double optical transitions involving the intermediate state.Moreover, a fast two-photon Rabi oscillation in ns timescale is manifested by employing intense lasers with an intensity of ~MW/cm^2, offering a possibility of ultrafast control of quantum dynamics with Rydberg atoms.展开更多
A theoretical calculation is carried out to investigate the spectrum of a barium Rydberg atom in an external magnetic field. Using an effective approach incorporating quantum defect into the centrifugal term in the Ha...A theoretical calculation is carried out to investigate the spectrum of a barium Rydberg atom in an external magnetic field. Using an effective approach incorporating quantum defect into the centrifugal term in the Hamiltonian, we reexamine the reported spectrum of the barium Rydberg atom in a magnetic field of 2.89 T [J. Phys. B 28 L537 (1995)]. Our calculation employs B-spline basis expansion and complex coordinate rotation techniques. For single photon absorption from the ground 6s2 to 6snp Rydberg states, the spectrum is not influenced by quantum defects of channels ns and nd. The calculation is in agreement with the experimental observations until the energy reaches E = 60 cm-1 . Beyond this energy, closer to the threshold, the calculated and experimental results do not agree with each other. Possible reasons for their discrepancies are discussed. Our study affirms an energy range where the diamagnetic spectrum of the barium atom can be explained thoroughly using a hydrogen model potential.展开更多
Closed-orbit theory is a semiclassical technique for explaining the spectra of Rydberg atoms in external fields. Using the closed-orbit theory and classical perturbation theory, we calculate the scaled recurrence spec...Closed-orbit theory is a semiclassical technique for explaining the spectra of Rydberg atoms in external fields. Using the closed-orbit theory and classical perturbation theory, we calculate the scaled recurrence spectra of Lithium atom in magnetic field plus a weak perpendicular electric field. The results show when the crossed electric field is added, the recurrence spectra are weakened greatly. As the scaled electric field f increases, the peaks of the recurrence spectra lose strength. Some recurrences are very sensitive and fall off rapidly as f increases; others persist till much higher f . As the electric field is stronger, some of the peaks revive. This phenomenon, caused by the interference among the electron waves that return to the nucleus, can be computed from the azimuthal dependence of the classical closed orbits.展开更多
The quantum swap gate is one of the most useful gates for quantum computation. Two-qubit entanglement and a controlled-NOT quantum gate in a neutral Rydberg atom system have been achieved in recent experiments. It is ...The quantum swap gate is one of the most useful gates for quantum computation. Two-qubit entanglement and a controlled-NOT quantum gate in a neutral Rydberg atom system have been achieved in recent experiments. It is therefore very interesting to propose a scheme here for swapping a quantum state between two trapped neutral atoms via the Rydberg blockade mechanism. The atoms interact with a sequence of laser pulses without individual addressing. The errors of the swap gate due to imprecision of pulse length, finite Rydberg interaction, and atomic spontaneous emission are discussed.展开更多
We report a sensitive detection of high Rydberg atom with large dipole moment utilizing its deflection near a pair of parallel cylindrical copper rods which are oppositely charged. When the low-field seeking state Ryd...We report a sensitive detection of high Rydberg atom with large dipole moment utilizing its deflection near a pair of parallel cylindrical copper rods which are oppositely charged. When the low-field seeking state Rydberg atoms fly across the gradient electric field formed by the pair of rods, they will be pushed away from the rods while the high-field seeking state ones will be attracted towards the rods. These atoms will form different patterns on an ion imaging system placed downwards at the end of the rods. The spatial distribution of the deflected atoms on the imaging system is also simulated,in good agreement with the experimental results, from which we can deduce the quantum state information of the excited atoms. This state resolvable Rydberg atom detection can be used for the dynamics research of the dipole–dipole interaction between atoms with large dipole moments.展开更多
We investigate the effect of van der Waals interactions and dipole-dipole interactions on collisional loss rate coefficients of Cs Rydberg nP states, and in detail analyze the variation of collisional loss coefficient...We investigate the effect of van der Waals interactions and dipole-dipole interactions on collisional loss rate coefficients of Cs Rydberg nP states, and in detail analyze the variation of collisional loss coefficients under the initial Rydberg atomic velocity and van der Waals interactions. We obtain the total collisional loss coefficients for different nP states, and provide the possible ionization mechanism for the results of experimental observation using our analysis model.展开更多
We achieve the robust nonadiabatic holonomic two-qubit controlled gate in one step based on the groundstate blockade mechanism between two Rydberg atoms. By using the Rydberg-blockade effect and the Raman transition m...We achieve the robust nonadiabatic holonomic two-qubit controlled gate in one step based on the groundstate blockade mechanism between two Rydberg atoms. By using the Rydberg-blockade effect and the Raman transition mechanism, we can produce the blockade effect of double occupation of the corresponding ground state,i.e., ground-state blockade, to encode the computational subspace into the ground state, thus effectively avoiding the spontaneous emission of the excited Rydberg state. On the other hand, the feature of geometric quantum computation independent of the evolutionary details makes the scheme robust to control errors. In this way,the controlled quantum gate constructed by our scheme not only greatly reduces the gate infidelity caused by spontaneous emission but is also robust to control errors.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61901495 and 12104509)
文摘The atomic-vapor cell is a vital component for Rydberg atomic microwave sensors,and impacts on overall capability of Rydberg sensors.However,the conventional analysis approach on effect of vapor-cell length contains two implicit assumptions,that is,the same atomic population density and buffer gas pressure,which make it unable to accurately capture actual response about effect of Rydberg-atom-based sensor performance on different Rydberg atom populations.Here,utilizing a stepped cesium atomic-vapor cell with five different dimensions at the same atomic population density and buffer gas pressure,the height and full width at half maximum of electromagnetically induced transparency(EIT)signal,and the sensitivity of the atomic superheterodyne sensor are comprehensively investigated under conditions of the same Rabi frequencies(saturated laser power).It is identified that EIT signal height is proportional to the cell length,full width at half maximum and sensitivity grow with the increment of cell length to a certain extent.Employing the coherent integration signal theory and atomic linear expansion coefficient method,theoretical analysis of the EIT height and sensitivity are further investigated.The results could shed new light on understanding and design of ultrahigh-sensitivity Rydberg atomic microwave sensors and find promising applications in quantum measurement,communication,and imaging.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12174106 and 11474094)the Science and Technology Commission of Shanghai Municipality(Grant No.18ZR1412800)。
文摘Strongly-interacting Rydberg atomic ensembles have shown intense collective excitation effects due to the inclusion of single Rydberg excitation shared by multiple atoms in the ensemble.In this paper we investigate a counter-intuitive Rydberg excitation facilitation with a strongly-interacting atomic ensemble in the strong probe-field regime,which is enabled by the role of a control atom nearby.Differing from the case of a single ensemble,we show that,the control atom's excitation adds to a second two-photon transition onto the doubly-excited Rydberg state,arising an excitation facilitation for the ensemble atoms.Our numerical studies depending on the method of quantum Monte Carlo wave function,exhibit the observation constraints of this excitation facilitation effect under practical experimental conditions.The results obtained can provide a flexible control for the excitation of Rydberg atomic ensembles and participate further uses in developing mesoscopic Rydberg gates for multiqubit quantum computation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12034012, 12074231, 12274272, and 61827824)Science and technology innovation plan of colleges and universities in Shanxi Province (Grant No. 2021L313)+2 种基金Science and Technology Project of State Grid (Grant No. 5700-202127198A-0-0-00)Fundamental Research Program of Shanxi Province (Grant No. 202203021222204)Taiyuan University of Science and Technology Scientific Research Initial Funding (Grant Nos. 20222008 and 20222132)。
文摘We demonstrate a simple method to measure electric field intensity by using doublet electromagnetically induced transparency(EIT) spectra of cold Rb Rydberg atoms, where the frequency of the coupling laser does not need to be locked. Based on the Stark splitting of the Rb Rydberg state, 10D_(3/2), under electric fields and the corresponding calculated polarizabilities, the real electric field intensity is calculated using the difference in radio-frequency diffraction between two acousto-optic modulators, which acts as a frequency criterion that allows us to measure the electrical field without locking the coupling laser. The value measured by this simple method shows a good agreement with our previous work [Opt.Express 29 1558(2021)] where the frequency of the coupling laser needs to be locked with an additional EIT spectrum based on atom vapor and a proportional–integral–differential feedback circuit. Our presented method can also be extended to the measurement of electric field based on hot Rydberg atom vapor, which has application in industry.
基金the LiaoNing Revitalization Talents Program(Grant No.XLYC1907033)the Natural Science Foundation of Liaoning Province(Grant No.2023-MS-072)+1 种基金the National Natural Science Foundation of China(Grant No.11905027)the Fundamental Research Funds for the Central Universities(Grant Nos.N2209005 and N2205015)。
文摘We present a scheme for dissipatively preparing bipartite Knill–Laflamme–Milburn(KLM)entangled state in a neutral atom system,where the spontaneous emission of excited Rydberg states,combined with the coherent population trapping,is actively exploited to engineer a steady KLM state from an arbitrary initial state.Instead of commonly used antiblockade dynamics of two Rydberg atoms,we particularly utilize the Rydberg–Rydberg interaction as the pumping source to drive the undesired states so that it is unnecessary to satisfy a certain relation with laser detuning.The numerical simulation of the master equation signifies that both the fidelity and the purity above 98%is available with the current feasible parameters,and the corresponding steady-state fidelity is robust to the variations of the dynamical parameters.
基金Project supported by the National Key R&D Program of China(Grant Nos.2018YFA0306504 and 2018YFA0306503)the Key-Area Research and Development Program of Guang Dong Province,China(Grant No.2019B030330001)+1 种基金the National Natural Science Foundation of China(Grant Nos.91636213,11654001,91736311,91836302,and U1930201)support from Beijing Academy of Quantum Information Sciences(BAQIS)Research Program(Grant No.Y18G24)。
文摘Quantum information processing based on Rydberg atoms emerged as a promising direction two decades ago.Recent experimental and theoretical progresses have shined exciting light on this avenue.In this concise review,we will briefly introduce the basics of Rydberg atoms and their recent applications in associated areas of neutral atom quantum computation and simulation.We shall also include related discussions on quantum optics with Rydberg atomic ensembles,which are increasingly used to explore quantum computation and quantum simulation with photons.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304900 and 2017YFA0402300)the Beijing Natural Science Foundation(Grant No.1212014)+3 种基金the National Natural Science Foundation of China(Grant Nos.11604334,11604177,and U2031125)the Key Research Program of the Chinese Academy of Sciences(Grant No.XDPB08-3)the Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics(Grant No.KF201807)the Fundamental Research Funds for the Central Universities,and Youth Innovation Promotion Association CAS.
文摘Recently,a Rydberg atom-based mixer was developed to measure the phase of a radio frequency(RF)field.The phase of the signal RF(SIG RF)field is down-converted directly to the phase of a beat signal created by the presence of a local RF(LO RF)field.In this study,we propose that the Rydberg atom-based mixer can be converted to an all-optical phase detector by amplitude modulation(AM)of the LO RF field;that is,the phase of the SIG RF field is related to both the amplitude and phase of the beat signal.When the AM frequency of the LO RF field is the same as the frequency of the beat signal,the beat signal will further interfere with the AM of the LO RF field inside the atom,and then the amplitude of the beat signal is related to the phase of the SIG RF field.The amplitude of the beat signal and the phase of the SIG RF field show a linear relationship within the range of 0 toπ/2 when the phase of the AM is set with a differenceπ/4 from the phase of the LO RF field.The minimum phase resolution can be as small as 0.6°by optimizing the experimental conditions according to a simple theoretical model.This study will expand and contribute to the development of RF measurement devices based on Rydberg atoms.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304203 and 2016YFF0200104)the National Natural Science Foundation of China(Grant Nos.61505099,61827824,91536110,and 61975104)the Fund for Shanxi ‘1331 Project’ Key Subjects Construction,Bairen Project of Shanxi Province,China
文摘Fluorescence loss spectrum for detecting cold Rydberg atoms with high sensitivity has been obtained based on lock-in detection of fluorescence of 6 P3/2 state when cooling lasers of the magneto-optical trap are modulated.The experiment results show that the signal to noise ratio has been improved by 32.64 dB when the modulation depth(converted to laser frequency)and frequency are optimized to 4 MHz and 6 kHz,respectively.This technique enables us to perform a highly sensitive non-destructive detection of Rydberg atoms.
基金the National R&D Program of China(Grant No.2017YFA0304203)the National Natural Science Foundation of China(Grant Nos.61875112,61705122,62075121,and 91736209)+1 种基金the Program for Sanjin Scholars of Shanxi Province,the Key Research and Development Program of Shanxi Province for International Cooperation(Grant No.201803D421034)Shanxi Scholarship Council of China(Grant Nos.2020-073),and 1331KSC.
文摘Rydberg atoms have been widely investigated due to their large size,long radiative lifetime,huge polarizability and strong dipole-dipole interactions.The position information of Rydberg atoms provides more possibilities for quantum optics research,which can be obtained under the localization method.We study the behavior of three-dimensional(3D)Rydberg atom localization in a four-level configuration with the measurement of the spatial optical absorption.The atomic localization precision depends strongly on the detuning and Rabi frequency of the involved laser fields.A 100%probability of finding the Rydberg atom at a specific 3D position is achieved with precision of~0.031λ.This work demonstrates the possibility for achieving the 3D atom localization of the Rydberg atom in the experiment.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2014AM030)
文摘We study the ionization of helium Rydberg atoms in an electric field above the classical ionization threshold within the semiclassical theory.By introducing a fractal approach to describe the chaotic dynamical behavior of the ionization,we identify the fractal self-similarity structure of the escape time versus the distribution of the initial launch angles of electrons,and find that the self-similarity region shifts toward larger initial launch angles with a decrease in the scaled energy.We connect the fractal structure of the escape time plot to the escape dynamics of ionized electrons.Of particular note is that the fractal dimensions are sensitively controlled by the scaled energy and magnetic field,and exhibit excellent agreement with the chaotic extent of the ionization systems for both helium and hydrogen Rydberg atoms.It is shown that,besides the electric and magnetic fields,core scattering is a primary factor in the fractal dynamics.
基金the National Natural Science Foundation of China(Grant No.12074061)。
文摘We study the steady optical response of a square lattice in which all trapped atoms are driven by a probe and a coupling fields into the ladder configuration of electromagnetically induced transparency(EIT).It turns out to be a manybody problem in the presence of van der Waals(vd W)interaction among atoms in the upmost Rydberg state,so Monte Carlo(MC)calculation based on density matrix equations have been done after introducing a sufficiently large cut-off radius.It is found that the absorption and dispersion of EIT spectra depends critically on a few key parameters like lattice dimension,unitary vd W shift,probe Rabi frequency,and coupling detuning.Through modulating these parameters,it is viable to change symmetries of the absorption and dispersion spectra and control on demand depth and position of the transparency window.Our MC calculation is expected to be instructive in understanding many-body quantum coherence effects and in manipulating non-equilibrium quantum phenomena by utilizing vd W interactions of Rydberg atoms.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA03044200 and 2016YFF0200104)the National Natural Science Foundation of China(Grant Nos.91536110,61505099,and 61378013)the Fund for Shanxi“331 Project”Key Subjects Construction,China
文摘The geometry effect of a vapor cell on the metrology of a microwave electric field is investigated. Based on the splitting of the electromagnetically induced transparency spectra of cesium Rydberg atoms in a vapor cell, high-resolution spatial distribution of the microwave electric field strength is achieved for both a cubic cell and a cylinder cell. The spatial distribution of the microwave field strength in two dimensions is measured with sub-wavelength resolution. The experimental results show that the shape of a vapor cell has a significant influence on the abnormal spatial distribution because of the Fabry–Pérot effect inside a vapor cell. A theoretical simulation is obtained for different vapor cell wall thicknesses and shows that a restricted wall thickness results in a measurement fluctuation smaller than 3% at the center of the vapor cell.
文摘We present a new method for computing the recurrence spectra of n≈40,m=0 lithium Rydberg atoms in strong parallel external electric and magnetic fields.This method is based on an extended closed-orbit theory allowing the computation of the scattering of the electron by the ionic core.We pay particular attention to the scaling properties,which are extremely important for understanding the correspondence between classical and quantum mechanics.The spectra with a constant scaled electric field F=0.01 and a scaled energy ε=-0.03 are recorded and compared with those of hydrogen obtained by the standard closed-orbit theory.The result shows that the additional strong resonance structures can be interpreted in terms of the core-scattered classical closed orbits.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304203)the State Key Program of the National Natural Science of China(Grant Nos.11434007 and 61835007)+1 种基金the National Natural Science Foundation of China(Grant Nos.61675123,61775124,and 11804202)the Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT 17R70).
文摘We present nonlinear spectra of four-level ladder cesium atoms employing 6 S1/2→6 P3/2→7 S1/2→30 P3/2 scheme of a room temperature vapor cell.A coupling laser drives Rydberg transition,a dressing laser couples two intermediate levels,and a probe laser optically probes the nonlinear spectra via electromagnetically induced transparency(EIT).Nonlinear spectra are detected as a function of coupling laser frequency.The observed spectra exhibit an enhanced absorption(EA) signal at coupling laser resonance to Rydberg transition and enhanced transmission(ET) signals at detunings to the transition.We define the enhanced absorption(transmission) strength,HEA(HET),and distance between two ET peaks,γET,to describe the spectral feature of the four-level atoms.The enhanced absorption signal HEA is found to have a maximum value when we vary the dressing laser Rabi frequency Ωd,corresponding Rabi frequency is defined as a separatrix point,ΩdSe.The values of ΩdSe and further η=ΩdSe/Ωc are found to depend on the probe and coupling Rabi frequency but not the atomic density.Based on ΩdSe,the spectra can be separated into two regimes,weak and strong dressing ranges,Ωd≤ΩdSe and Ωd≥QdSe,respectively.The spectroscopies display different features at these two regimes.A four-level theoretical model is developed that agrees well with the experimental results in terms of the probe-beam absorption behavior of Rabi frequency-dependent dressed states.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474094,11104076,and 11574086)the Science and Technology Commission of Shanghai Municipality,China(Grant Nos.18ZR1412800 and 16QA1401600)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20110076120004)
文摘Motivated by experimental advances that the collective excitation of two Rydberg atoms was observed, we provide an elaborate theoretical study for the dynamical behavior of two-atom Rabi oscillations. In the large-intermediate-detuning case, the two-photon Rabi oscillation is found to be significantly affected by the strength of the interatomic van der Waals interaction. With a careful comparison of the exact numbers and values of the oscillation frequency, we propose a new way to determine the strength of excitation blockade, agreeing well with the previous universal criterion for full, partial, and no blockade regions. In the small-intermediate-detuning case, we find a blockade-like effect, but the collective enhancement factor is smaller than ^(1/2) due to the quantum interference of double optical transitions involving the intermediate state.Moreover, a fast two-photon Rabi oscillation in ns timescale is manifested by employing intense lasers with an intensity of ~MW/cm^2, offering a possibility of ultrafast control of quantum dynamics with Rydberg atoms.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174329 and 91121005)the National Basic Research Program of China(Grant Nos.2012CB922101 and 2013CB922003)
文摘A theoretical calculation is carried out to investigate the spectrum of a barium Rydberg atom in an external magnetic field. Using an effective approach incorporating quantum defect into the centrifugal term in the Hamiltonian, we reexamine the reported spectrum of the barium Rydberg atom in a magnetic field of 2.89 T [J. Phys. B 28 L537 (1995)]. Our calculation employs B-spline basis expansion and complex coordinate rotation techniques. For single photon absorption from the ground 6s2 to 6snp Rydberg states, the spectrum is not influenced by quantum defects of channels ns and nd. The calculation is in agreement with the experimental observations until the energy reaches E = 60 cm-1 . Beyond this energy, closer to the threshold, the calculated and experimental results do not agree with each other. Possible reasons for their discrepancies are discussed. Our study affirms an energy range where the diamagnetic spectrum of the barium atom can be explained thoroughly using a hydrogen model potential.
文摘Closed-orbit theory is a semiclassical technique for explaining the spectra of Rydberg atoms in external fields. Using the closed-orbit theory and classical perturbation theory, we calculate the scaled recurrence spectra of Lithium atom in magnetic field plus a weak perpendicular electric field. The results show when the crossed electric field is added, the recurrence spectra are weakened greatly. As the scaled electric field f increases, the peaks of the recurrence spectra lose strength. Some recurrences are very sensitive and fall off rapidly as f increases; others persist till much higher f . As the electric field is stronger, some of the peaks revive. This phenomenon, caused by the interference among the electron waves that return to the nucleus, can be computed from the azimuthal dependence of the classical closed orbits.
基金supported by the National Natural Science Foundation of China (Grant No. 10974028)the Doctoral Foundation of the Ministry of Education of China (Grant No. 20093514110009)+3 种基金the Natural Science Foundation of Fujian Province of China (Grant No. 2009J06002)the Fund from Fuzhou University (Grant No. 022408)the National Basic Research Program of China (Grant Nos. 2011CB921200 and 2011CBA00200)the China Postdoctoral Science Foundation (Grant No. 20110490828)
文摘The quantum swap gate is one of the most useful gates for quantum computation. Two-qubit entanglement and a controlled-NOT quantum gate in a neutral Rydberg atom system have been achieved in recent experiments. It is therefore very interesting to propose a scheme here for swapping a quantum state between two trapped neutral atoms via the Rydberg blockade mechanism. The atoms interact with a sequence of laser pulses without individual addressing. The errors of the swap gate due to imprecision of pulse length, finite Rydberg interaction, and atomic spontaneous emission are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91421305,91121005,and 11674359)the National Key Basic Research Program of China(Grant No.2013CB922003)
文摘We report a sensitive detection of high Rydberg atom with large dipole moment utilizing its deflection near a pair of parallel cylindrical copper rods which are oppositely charged. When the low-field seeking state Rydberg atoms fly across the gradient electric field formed by the pair of rods, they will be pushed away from the rods while the high-field seeking state ones will be attracted towards the rods. These atoms will form different patterns on an ion imaging system placed downwards at the end of the rods. The spatial distribution of the deflected atoms on the imaging system is also simulated,in good agreement with the experimental results, from which we can deduce the quantum state information of the excited atoms. This state resolvable Rydberg atom detection can be used for the dynamics research of the dipole–dipole interaction between atoms with large dipole moments.
文摘We investigate the effect of van der Waals interactions and dipole-dipole interactions on collisional loss rate coefficients of Cs Rydberg nP states, and in detail analyze the variation of collisional loss coefficients under the initial Rydberg atomic velocity and van der Waals interactions. We obtain the total collisional loss coefficients for different nP states, and provide the possible ionization mechanism for the results of experimental observation using our analysis model.
基金supported by the Special Project for Research and Development in Key Areas of Guangdong Province(Grant No.2020B0303300001)the National Natural Science Foundation of China(Grant Nos.U21A20434 and 12074346)the Natural Science Foundation of Henan Province(Grant No.212300410085)。
文摘We achieve the robust nonadiabatic holonomic two-qubit controlled gate in one step based on the groundstate blockade mechanism between two Rydberg atoms. By using the Rydberg-blockade effect and the Raman transition mechanism, we can produce the blockade effect of double occupation of the corresponding ground state,i.e., ground-state blockade, to encode the computational subspace into the ground state, thus effectively avoiding the spontaneous emission of the excited Rydberg state. On the other hand, the feature of geometric quantum computation independent of the evolutionary details makes the scheme robust to control errors. In this way,the controlled quantum gate constructed by our scheme not only greatly reduces the gate infidelity caused by spontaneous emission but is also robust to control errors.
