We propose a wire configuration to create a one-dimensional （1D） array of magnetic microtraps for trapping ultracold atoms. The configuration is formed by replacing the central part of the Z-wire pattern with a zigz...We propose a wire configuration to create a one-dimensional （1D） array of magnetic microtraps for trapping ultracold atoms. The configuration is formed by replacing the central part of the Z-wire pattern with a zigzag wire. We simulate the performance of this pattern by the finite element method which can take both the width and depth of the wire into consideration. The result of simulation shows that this configuration can create magnetic microtraps which can be separated and combined by changing bias magnetic field. We manage to split Z-wire trap and prove that similar result can occur for the new wire configuration. The fabrication processes of the atom chip are also introduced. Finally we discuss the loading method.展开更多
We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which i...We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which is split into two separate parts by switching on the current of the U-wire. The two separate atom clouds have a distance more than one millimeter apart from each other and show almost symmetrical profiles, corresponding to about a 50/50 splitting ratio.展开更多
We demonstrate a precision measurement of local gravity acceleration 9 in Wuhan by a compact cold atom interferometer. The atom interferometer is in vertical Mach-Zehnder configuration realized using a 7r /2 - π - π...We demonstrate a precision measurement of local gravity acceleration 9 in Wuhan by a compact cold atom interferometer. The atom interferometer is in vertical Mach-Zehnder configuration realized using a 7r /2 - π - π /2 Raman pulse sequence. Cold atoms were prepared in a magneto-optical trap, launched upward to form an atom fountain, and then coherently manipulated to interfere by stimulated Raman transition. Population signal vs Raman laser phase was recorded as interference fringes, and the local gravity was deduced from the interference signal. We have obtained a resolution of 7 × 10-9g after an integration time of 236s under the best vibrational environment conditions. The absolute g value was derived from the chirp rate with a difference of 1.5 × 10--07 g compared to the gravity reference value. The tidal phenomenon was observed by continuously monitoring the local gravity over 123 h.展开更多
Cbld-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with ...Cbld-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with cold atoms. Cold rubidium atoms are prepared in a magneto-optical trap and are pushed by resonant laser pulse to form slow atomic beam. In the interference region, atomic wave packets are coherently manipulated using π/2 -π - π/2 Raman pulse sequences. Interference fringes with maximum contrast of 37% are observed experimentally.展开更多
We present a scheme for generating a ring magnetic waveguide on a single-layer atom chip. The wire layout consists of two interleaved Archimedean spirals of the same size. The waveguide avoids the trapping perturbatio...We present a scheme for generating a ring magnetic waveguide on a single-layer atom chip. The wire layout consists of two interleaved Archimedean spirals of the same size. The waveguide avoids the trapping perturbation caused by the input and output ports, resulting in an enclosed guiding loop for neutral atoms in weak-field seeking states. Such a configuration can create a tight and deep trap potential with a small current. Taking the [F = 2, mF =2} state of 87Rb as an example, the trap frequency and depth are estimated to be 18kHz and 335 μK, respectively, with adc current of 2 A.展开更多
We calculate the reflection probability for ultracold alkali atoms incident on a solid surface. By considering the interatomic interaction and using the WKB method, it is shown that the repulsive interaction between a...We calculate the reflection probability for ultracold alkali atoms incident on a solid surface. By considering the interatomic interaction and using the WKB method, it is shown that the repulsive interaction between atoms has the effect of increasing the reflection probability. The increasing amplitude is related with the interatomic interaction and the depth of atom-surface potential. In addition, we also perform a numerical calculation to testify the effect of the interatomic interaction, and the analytic result is proven by the numerical result.展开更多
We transfer cold ^87 Rb atoms from a vapour cell chamber to a spatially separated UHV magneto-optical trap （MOT） with the assistance of a red-detuned optical guiding beam and a normal push beam. Efficient optical gu...We transfer cold ^87 Rb atoms from a vapour cell chamber to a spatially separated UHV magneto-optical trap （MOT） with the assistance of a red-detuned optical guiding beam and a normal push beam. Efficient optical guiding of the cold atoms is observed within a small detuning window. A pulsed optical guiding beam enhances the transfer efficiency and hence allows us to collect more atoms in UHV MOT in a shorter time, which is favourable for our experiment of achieving Bose-Einstein condensates （BEC）. Besides the easy operation, another advantage of this optical guiding technique is also demonstrated such that slower atomic beams may be efficiently transferred along horizontal direction. This study is a direct application of the optical guiding technique as a powerful tool.展开更多
We report the experimental investigation of electromagnetically induced transparency （EIT） in a Zeeman-sublevels A-type system of cold 87Rb atoms in free space. We use the Zeeman substates of the hyperfine energy st...We report the experimental investigation of electromagnetically induced transparency （EIT） in a Zeeman-sublevels A-type system of cold 87Rb atoms in free space. We use the Zeeman substates of the hyperfine energy states 52 S 1/2, F =- 2 and 52P3/2, F1 = 2 of 87Rb D2 line to form a A-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 kHz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock （Yan B, et al. 2009 Phys. Rev. A 79 063820）.展开更多
We propose a simple single-layer magnetic microtrap configuration which can trap an array of magneticallytrapped Bose-Einstein condensate. The configuration consists of two series of parallel wires perpendicular to ea...We propose a simple single-layer magnetic microtrap configuration which can trap an array of magneticallytrapped Bose-Einstein condensate. The configuration consists of two series of parallel wires perpendicular to each other and all of the crossing points are cut off for maintaining the uniformity of the current. We analyse the trapping potential, the position of trapping centres and the uniformity of the array of the traps. The trapping depth and trapping frequency with different parameters are also calculated. Lastly, the effect of the cut-off crossing points, dissipate power, chip production are introduced concisely.展开更多
We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps（OFMTs） with 790 nm（for -（87...We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps（OFMTs） with 790 nm（for -（87）Rb） circularly polarized laser beams and state-dependent potentials simultaneously for two internal atomic states with microwave coplanar waveguides. We carry out numerical calculations and simulations for controlled collisional interactions between OFMTs and addressable single atoms＇ manipulation on our designed hybrid atom chips. The results show that our proposed platform is feasible and flexible, which has wide applications including collisional dynamics investigation, entanglement generation,and scalable quantum gates implementation.展开更多
We experimentally observe the dynamic evolution of atoms in the evaporative cooling, by in-situ imaging the plugged hole of ultracold atoms. Ultracold rubidium atoms confined in a magnetic trap are plugged using a blu...We experimentally observe the dynamic evolution of atoms in the evaporative cooling, by in-situ imaging the plugged hole of ultracold atoms. Ultracold rubidium atoms confined in a magnetic trap are plugged using a blue-detuned laser beam with a waist of 20 m at a wavelength of 767 nm. We probe the variation of the atomic temperature and width versus the radio frequency in the evaporative cooling. Both the behaviors are in good agreement with the calculation of the trapping potential dressed by the rf signal above the threshold temperature,while deviating from the calculation near the phase transition. To accurately obtain the atomic width, we use the plugged hole as the reference to optimize the optical imaging system by precisely minimizing the artificial structures due to the defocus effect.展开更多
We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase ...We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase shift and contrast of the interference fringe are experimentally investigated. The results show that the contrast of the interference fringe is well held when the platform is rotated, and the phase shift of the interference fringe is linearly proportional to the rotation rate of the platform. The long-term stability, which is evaluated by the overlapped Allan deviation, is 8.5 × 10^-6 rad/s over the integrating time of 1000s.展开更多
We propose a simple scheme to generate an arbitrary photon-added coherent state of a travelling optical field by combining an array of degenerate parametric amplifiers and corresponding single-photon detectors. Partic...We propose a simple scheme to generate an arbitrary photon-added coherent state of a travelling optical field by combining an array of degenerate parametric amplifiers and corresponding single-photon detectors. Particularly, when the single-photon-added coherent state is observed by developing the novel technique of Zavatta et al （2004 Science 306 660）, we can simultar/eously obtain the generalized N-qubit W state.展开更多
Systematic error suppression and test data processing are very important in improving the accuracy and sensitivity of the atom interferometer(AI)-based weak-equivalence-principle(WEP) test in space. Here we present a ...Systematic error suppression and test data processing are very important in improving the accuracy and sensitivity of the atom interferometer(AI)-based weak-equivalence-principle(WEP) test in space. Here we present a spectrum correlation method to investigate the test data of the AI-based WEP test in space by analyzing the characteristics of systematic errors and noises. The power spectrum of the Eotvos coefficient η, systematic errors, and noises in AI-based WEP test in space are analyzed and calculated in detail. By using the method, the WEP violation signal is modulated from direct current(DC) frequency band to alternating current(AC) frequency band. We find that the signal can be effectively extracted and the influence of systematic errors can be greatly suppressed by analyzing the power spectrum of the test data when the spacecraft is in an inertial pointing mode. Furthermore, the relation between the Eotvos coefficient η and the number of measurements is obtained under certain simulated parameters. This method will be useful for both isotopic and nonisotopic AI-based WEP tests in space.展开更多
We demonstrate high-fidelity manipulation of the quantized motion of a single87Rb atom in an optical tweezer via microwave couplings induced by Stern–Gerlach splitting. The Stern–Gerlach splitting is mediated by pol...We demonstrate high-fidelity manipulation of the quantized motion of a single87Rb atom in an optical tweezer via microwave couplings induced by Stern–Gerlach splitting. The Stern–Gerlach splitting is mediated by polarization gradient of a strongly focused tweezer beam that functions as fictitious magnetic field gradient. The spatial splitting removes the orthogonality of the atomic spatial wavefunctions, thus enables the microwave couplings between the motional states. We obtain coherent Rabi oscillations for up to third-order sideband transitions, in which a high fidelity of larger than 0.99 is obtained for the spin-flip transition on the first order sideband after subtraction of the state preparation and detection error. The Stern–Gerlach splitting is measured at a precision of better than 0.05 nm. This work paves the way for quantum engineering of motional states of single atoms, and may have wide applications in few body physics and ultracold chemistry.展开更多
We demonstrate an experimental observation of coherent population trapping-Ramsey interference in cold 87Rb atoms by employing the time-domain separated oscillatory fields＇ method. The interference fringe with line w...We demonstrate an experimental observation of coherent population trapping-Ramsey interference in cold 87Rb atoms by employing the time-domain separated oscillatory fields＇ method. The interference fringe with line width of 80 Hz is obtained. We propose a novel method to measure the cold atom number. The measurement is insensitive to the pump beam intensity, the single photon detuning and even the initial state population. We use this method to normalize the interference signal and to improve the signal-to-noise ratio significantly.展开更多
The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field e...The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field exhibit squeezing in the out-of-phase quadrature. The coupling between the atom and the cavity mode can greatly enhance the squeezing centred at the laser frequency. More importantly, for strong excitation, under the effect of the cavity-atom coupling, the in-phase quadrature of fluorescence can exhibit two-mode squeezing at the two inner sideband frequencies. By working in the dressed-state representation and hiring secular approximation, we give an analytical explanation for the effect. The result shows, under appropriate conditions, the squeezing can be greatly enhanced by appropriately tuning the cavity resonant frequency.展开更多
We report an experiment of trapping of neutral ^87Rb atoms on a self-made atomchip. The H-shaped atomchip is made by magnetron sputtering technology, which is different from the atomchip technology of other teams. We ...We report an experiment of trapping of neutral ^87Rb atoms on a self-made atomchip. The H-shaped atomchip is made by magnetron sputtering technology, which is different from the atomchip technology of other teams. We collect 3×10^6 ^87Rb atoms in the mirror magneto-optical trap （MOT） using the external MOT coils, and 1×10^5 ^87 Rb atoms are transferred to U-MOT using U-shaped wire in chip and a pair of bias coils.展开更多
We present the experimental observation of the Fano-type interference in a coupled cavity-atom system by confining the laser-cooled ^85Rb atoms in an optical cavity. The asymmetric Fano profile is obtained through qua...We present the experimental observation of the Fano-type interference in a coupled cavity-atom system by confining the laser-cooled ^85Rb atoms in an optical cavity. The asymmetric Fano profile is obtained through quantum interference in a three-level atomic system coherently coupled to a single mode cavity field. The observed Fano profile can be explained by the interference between the intra-cavity dark state and the polariton state of the coupled cavity atom system. The possible applications of our observations include all-optical switching, optical sensing and narrow band optical filters.展开更多
We present a scheme to generate cluster states with many scheme, no transfer of quantum information between the atoms in cavity QED via Raman transition. In this atoms and cavities is required, the cavity fields are o...We present a scheme to generate cluster states with many scheme, no transfer of quantum information between the atoms in cavity QED via Raman transition. In this atoms and cavities is required, the cavity fields are only virtually excited and thus the cavity decay is suppressed during the generation of cluster states. The atoms are always populated in the two ground states. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. We also show how to transfer quantum information from one atom to another.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2006CB921202)the National Natural Science Foundation of China(Grant No.10974210)
文摘We propose a wire configuration to create a one-dimensional （1D） array of magnetic microtraps for trapping ultracold atoms. The configuration is formed by replacing the central part of the Z-wire pattern with a zigzag wire. We simulate the performance of this pattern by the finite element method which can take both the width and depth of the wire into consideration. The result of simulation shows that this configuration can create magnetic microtraps which can be separated and combined by changing bias magnetic field. We manage to split Z-wire trap and prove that similar result can occur for the new wire configuration. The fabrication processes of the atom chip are also introduced. Finally we discuss the loading method.
基金supported by the State Key Basic Research Program of China(Grant No.2011CB921504)the National Natural Science Foundation of China(Grant No.91536107)
文摘We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which is split into two separate parts by switching on the current of the U-wire. The two separate atom clouds have a distance more than one millimeter apart from each other and show almost symmetrical profiles, corresponding to about a 50/50 splitting ratio.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10827404 and 10774160, the National Basic Research Program of China under Grant Nos 2010CB832805, and the Funds from the Chinese Academy of Sciences.
文摘We demonstrate a precision measurement of local gravity acceleration 9 in Wuhan by a compact cold atom interferometer. The atom interferometer is in vertical Mach-Zehnder configuration realized using a 7r /2 - π - π /2 Raman pulse sequence. Cold atoms were prepared in a magneto-optical trap, launched upward to form an atom fountain, and then coherently manipulated to interfere by stimulated Raman transition. Population signal vs Raman laser phase was recorded as interference fringes, and the local gravity was deduced from the interference signal. We have obtained a resolution of 7 × 10-9g after an integration time of 236s under the best vibrational environment conditions. The absolute g value was derived from the chirp rate with a difference of 1.5 × 10--07 g compared to the gravity reference value. The tidal phenomenon was observed by continuously monitoring the local gravity over 123 h.
文摘Cbld-matter-wave Sagnac interferometers possess many advantages over their thermal atomic beam counterparts when they are used as precise inertial sensors. We report a realization of a Sagnac-type interferometer with cold atoms. Cold rubidium atoms are prepared in a magneto-optical trap and are pushed by resonant laser pulse to form slow atomic beam. In the interference region, atomic wave packets are coherently manipulated using π/2 -π - π/2 Raman pulse sequences. Interference fringes with maximum contrast of 37% are observed experimentally.
基金Supported by the National Basic Research Program of China under Grant No 2001CB309307the National Natural Science Foundation of China under Grant Nos 10974210 and 10474105
文摘We present a scheme for generating a ring magnetic waveguide on a single-layer atom chip. The wire layout consists of two interleaved Archimedean spirals of the same size. The waveguide avoids the trapping perturbation caused by the input and output ports, resulting in an enclosed guiding loop for neutral atoms in weak-field seeking states. Such a configuration can create a tight and deep trap potential with a small current. Taking the [F = 2, mF =2} state of 87Rb as an example, the trap frequency and depth are estimated to be 18kHz and 335 μK, respectively, with adc current of 2 A.
基金Supported by the National Natural Science Foundation of China under Grant No 10747164, and the National Basic Research Programme of China under Grant No 2006CB921203, and the Chinese Academy of Sciences.
文摘We calculate the reflection probability for ultracold alkali atoms incident on a solid surface. By considering the interatomic interaction and using the WKB method, it is shown that the repulsive interaction between atoms has the effect of increasing the reflection probability. The increasing amplitude is related with the interatomic interaction and the depth of atom-surface potential. In addition, we also perform a numerical calculation to testify the effect of the interatomic interaction, and the analytic result is proven by the numerical result.
基金Supported by National Natural Science Foundation of China under Grant No 10574142, the National Basic Research Programme of China under Grant No 2006CB921406, and Chinese Academy of Sciences.
文摘We transfer cold ^87 Rb atoms from a vapour cell chamber to a spatially separated UHV magneto-optical trap （MOT） with the assistance of a red-detuned optical guiding beam and a normal push beam. Efficient optical guiding of the cold atoms is observed within a small detuning window. A pulsed optical guiding beam enhances the transfer efficiency and hence allows us to collect more atoms in UHV MOT in a shorter time, which is favourable for our experiment of achieving Bose-Einstein condensates （BEC）. Besides the easy operation, another advantage of this optical guiding technique is also demonstrated such that slower atomic beams may be efficiently transferred along horizontal direction. This study is a direct application of the optical guiding technique as a powerful tool.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB921504)the National Natural Science Foundation of China(Grant No.91536107)
文摘We report the experimental investigation of electromagnetically induced transparency （EIT） in a Zeeman-sublevels A-type system of cold 87Rb atoms in free space. We use the Zeeman substates of the hyperfine energy states 52 S 1/2, F =- 2 and 52P3/2, F1 = 2 of 87Rb D2 line to form a A-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 kHz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock （Yan B, et al. 2009 Phys. Rev. A 79 063820）.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10334050 and 10474105, the State Key Basic Research Programme of China under Grant No 2006CB921202, and the Key 0riental Project of Chinese Academy of Sciences under Grant Nos KGCX2-SW-100 and KGCX3-SYW-405.
文摘We propose a simple single-layer magnetic microtrap configuration which can trap an array of magneticallytrapped Bose-Einstein condensate. The configuration consists of two series of parallel wires perpendicular to each other and all of the crossing points are cut off for maintaining the uniformity of the current. We analyse the trapping potential, the position of trapping centres and the uniformity of the array of the traps. The trapping depth and trapping frequency with different parameters are also calculated. Lastly, the effect of the cut-off crossing points, dissipate power, chip production are introduced concisely.
基金Project supported by the National Key Research and Development Program of China(Grant No.2016YFA0302800)the National Natural Science Foundation of China(Grant No.11674361)
文摘We propose a novel on-chip platform for controlling and manipulating cold atoms precisely and coherently. The scheme is achieved by producing optically induced fictitious magnetic traps（OFMTs） with 790 nm（for -（87）Rb） circularly polarized laser beams and state-dependent potentials simultaneously for two internal atomic states with microwave coplanar waveguides. We carry out numerical calculations and simulations for controlled collisional interactions between OFMTs and addressable single atoms＇ manipulation on our designed hybrid atom chips. The results show that our proposed platform is feasible and flexible, which has wide applications including collisional dynamics investigation, entanglement generation,and scalable quantum gates implementation.
基金Supported by the National Key Research and Development Program of China under Grant No 2016YFA0301503the National Natural Science Foundation of China under Grant Nos 11674358 and 11434015the Instrument Project of the Chinese Academy of Sciences under Grant No YJKYYQ20170025
文摘We experimentally observe the dynamic evolution of atoms in the evaporative cooling, by in-situ imaging the plugged hole of ultracold atoms. Ultracold rubidium atoms confined in a magnetic trap are plugged using a blue-detuned laser beam with a waist of 20 m at a wavelength of 767 nm. We probe the variation of the atomic temperature and width versus the radio frequency in the evaporative cooling. Both the behaviors are in good agreement with the calculation of the trapping potential dressed by the rf signal above the threshold temperature,while deviating from the calculation near the phase transition. To accurately obtain the atomic width, we use the plugged hole as the reference to optimize the optical imaging system by precisely minimizing the artificial structures due to the defocus effect.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11227083 and 91536221
文摘We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase shift and contrast of the interference fringe are experimentally investigated. The results show that the contrast of the interference fringe is well held when the platform is rotated, and the phase shift of the interference fringe is linearly proportional to the rotation rate of the platform. The long-term stability, which is evaluated by the overlapped Allan deviation, is 8.5 × 10^-6 rad/s over the integrating time of 1000s.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10304020 and 10474117）, the State Key Development Program for Basic Research of China （Grant No 2001CB309309）, and also in part by the Sunshine Project of Wuhan, China.
文摘We propose a simple scheme to generate an arbitrary photon-added coherent state of a travelling optical field by combining an array of degenerate parametric amplifiers and corresponding single-photon detectors. Particularly, when the single-photon-added coherent state is observed by developing the novel technique of Zavatta et al （2004 Science 306 660）, we can simultar/eously obtain the generalized N-qubit W state.
基金Project supported by the National Natural Science Foundation of China(Grants No.11947057)the Foundation for Distinguished Young Scientist of Jiangxi Province,China(Grant No.2016BCB23009)the Postdoctoral Applied Research Program of Qingdao City,Shandong Province,China(Grant No.62350079311135).
文摘Systematic error suppression and test data processing are very important in improving the accuracy and sensitivity of the atom interferometer(AI)-based weak-equivalence-principle(WEP) test in space. Here we present a spectrum correlation method to investigate the test data of the AI-based WEP test in space by analyzing the characteristics of systematic errors and noises. The power spectrum of the Eotvos coefficient η, systematic errors, and noises in AI-based WEP test in space are analyzed and calculated in detail. By using the method, the WEP violation signal is modulated from direct current(DC) frequency band to alternating current(AC) frequency band. We find that the signal can be effectively extracted and the influence of systematic errors can be greatly suppressed by analyzing the power spectrum of the test data when the spacecraft is in an inertial pointing mode. Furthermore, the relation between the Eotvos coefficient η and the number of measurements is obtained under certain simulated parameters. This method will be useful for both isotopic and nonisotopic AI-based WEP tests in space.
基金Supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304501,2016YFA0302800 and 2016YFA0302002)the Key Research Program of Frontier Science of the Chinese Academy of Sciences(CAS)(Grant No.ZDBS-LY-SLH012)+2 种基金the National Natural Science Foundation of China(Grant No.11774389)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21010100)the Youth Innovation Promotion Association CAS(Grant No.2019325).
文摘We demonstrate high-fidelity manipulation of the quantized motion of a single87Rb atom in an optical tweezer via microwave couplings induced by Stern–Gerlach splitting. The Stern–Gerlach splitting is mediated by polarization gradient of a strongly focused tweezer beam that functions as fictitious magnetic field gradient. The spatial splitting removes the orthogonality of the atomic spatial wavefunctions, thus enables the microwave couplings between the motional states. We obtain coherent Rabi oscillations for up to third-order sideband transitions, in which a high fidelity of larger than 0.99 is obtained for the spin-flip transition on the first order sideband after subtraction of the state preparation and detection error. The Stern–Gerlach splitting is measured at a precision of better than 0.05 nm. This work paves the way for quantum engineering of motional states of single atoms, and may have wide applications in few body physics and ultracold chemistry.
基金Supported by the National Basic Research Program of China under Grant Nos 2005CB724505 and 2010CB832805, the National Natural Science Foundation of China under Grant No 10774160, and Wuhan National Laboratory for Optoelectronics under Grant No P080001.
文摘We demonstrate an experimental observation of coherent population trapping-Ramsey interference in cold 87Rb atoms by employing the time-domain separated oscillatory fields＇ method. The interference fringe with line width of 80 Hz is obtained. We propose a novel method to measure the cold atom number. The measurement is insensitive to the pump beam intensity, the single photon detuning and even the initial state population. We use this method to normalize the interference signal and to improve the signal-to-noise ratio significantly.
基金Supported by the National Basic Research Programme of China under Grant No 2006CB921203, the National Natural Science Foundation of China under Grant No 10474119, the Chinese Academy of Sciences, and China Postdoctoral Science Foundation.
文摘The quadrature squeezing spectra in the resonance fluorescence of a V-type three-level atom driven by a coherent field and coupled to a single-mode cavity is investigated. For weak excitation, the fluorescence field exhibit squeezing in the out-of-phase quadrature. The coupling between the atom and the cavity mode can greatly enhance the squeezing centred at the laser frequency. More importantly, for strong excitation, under the effect of the cavity-atom coupling, the in-phase quadrature of fluorescence can exhibit two-mode squeezing at the two inner sideband frequencies. By working in the dressed-state representation and hiring secular approximation, we give an analytical explanation for the effect. The result shows, under appropriate conditions, the squeezing can be greatly enhanced by appropriately tuning the cavity resonant frequency.
基金Supported by the State Key Basic Research Programme of China under Grant No 2001CB309307, the National Natural Science Foundation of China under Grant No 10334050, and the Key 0riental Project of Chinese Academy of Sciences under Grant No KGCX2-SVV- 100.
文摘We report an experiment of trapping of neutral ^87Rb atoms on a self-made atomchip. The H-shaped atomchip is made by magnetron sputtering technology, which is different from the atomchip technology of other teams. We collect 3×10^6 ^87Rb atoms in the mirror magneto-optical trap （MOT） using the external MOT coils, and 1×10^5 ^87 Rb atoms are transferred to U-MOT using U-shaped wire in chip and a pair of bias coils.
基金Supported by the National Basic Research Program of China under Grant No 2012CB922101the National Natural Science Foundation of China under Grant No 11404375supported by the National Science Foundation of USA under Grant No 1205565
文摘We present the experimental observation of the Fano-type interference in a coupled cavity-atom system by confining the laser-cooled ^85Rb atoms in an optical cavity. The asymmetric Fano profile is obtained through quantum interference in a three-level atomic system coherently coupled to a single mode cavity field. The observed Fano profile can be explained by the interference between the intra-cavity dark state and the polariton state of the coupled cavity atom system. The possible applications of our observations include all-optical switching, optical sensing and narrow band optical filters.
基金Supported by the National Natural Science Foundation of China under Grant No 60478029.
文摘We present a scheme to generate cluster states with many scheme, no transfer of quantum information between the atoms in cavity QED via Raman transition. In this atoms and cavities is required, the cavity fields are only virtually excited and thus the cavity decay is suppressed during the generation of cluster states. The atoms are always populated in the two ground states. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. We also show how to transfer quantum information from one atom to another.
