Temperature,as a measure of thermal motion,is a significant parameter characterizing a cold atomic ensemble optical quantum memory.In a cold gas,storage lifetime strongly depends on its temperature and is associated w...Temperature,as a measure of thermal motion,is a significant parameter characterizing a cold atomic ensemble optical quantum memory.In a cold gas,storage lifetime strongly depends on its temperature and is associated with the spin wave decoherence.Here we experimentally demonstrate a new spin wave thermometry method relying on this direct dependence.The short-wavelength spin waves resulting from the counter-propagating configuration of the control and the probe laser beams make this thermometry highly suitable for probing in situ the atomic motion in elongated clouds as the ones used in quantum memories.Our technique is realized with comparable precision for memories that rely on electromagnetically induced transparency as well as far-detuned Raman storage.展开更多
As proposed by Herminghaus, a hierarchical structure could render any surface nonwettable as long as the roughness amplitude at small scales is sufficient to suspend a free liquid surface. Recently we reported that th...As proposed by Herminghaus, a hierarchical structure could render any surface nonwettable as long as the roughness amplitude at small scales is sufficient to suspend a free liquid surface. Recently we reported that the wettability of La0.7Sr0.3MnO3, an intrinsic hydrophilic oxide, can be tuned from superhydrophilicity to superhydrophobicity by hierarchical microstructures generated by annealing the coatings of La0.7Sr0.3MnO3 powder in nanometric scale at different temperatures. Here we further demonstrate the similar phenomenon observed on LaMaO3 coatings, which conforms THAT the surface geometrical structure is a key factor to determine the wettability.展开更多
We present a cold atom system with a dark-line two-dimensional magneto-optical trap, to increase the atomic density by suppressing the atomic radiation pressure. Optical depth （OD） and duty cycle are used to evaluat...We present a cold atom system with a dark-line two-dimensional magneto-optical trap, to increase the atomic density by suppressing the atomic radiation pressure. Optical depth （OD） and duty cycle are used to evaluate the system performance. We demonstrate a 100% increase in OD with the dark line, and obtain an ultrahigh OD of 264 with 10% for the duty cycle. Also, with an efficient dark line region, the OD could maintain above i00 with duty cycle as high as 30%. The cold atomic ensemble with an ultrahigh OD with a 10%-30% duty cycle is particularly advantageous in quantum i^formation processing and communication.展开更多
A photon source with high-dimensional entanglement is able to bring increasing capacity of information in quantum communication.The dimensionality is determined by the chosen degree of freedom of the photons and is li...A photon source with high-dimensional entanglement is able to bring increasing capacity of information in quantum communication.The dimensionality is determined by the chosen degree of freedom of the photons and is limited by the complexity of the physical systems.Here we propose a new type of high-dimensional entangled photon source,generated via path-indistinguishable scheme from a two-dimensional atomic cloud,which is prepared in a magneto-optical trap.To verify the photon source,we demonstrate experimentally the quantum state of the single photons heralded by its partner photon,with homodyne tomographic technology.展开更多
We investigate photon coalescence in a lossy non-Hermitian system and study a dynamic device modeled by a beam splitter with an extra intrinsic phase term added in the transformation matrix,with which the device is a ...We investigate photon coalescence in a lossy non-Hermitian system and study a dynamic device modeled by a beam splitter with an extra intrinsic phase term added in the transformation matrix,with which the device is a lossy non-Hermitian linear system.The two-photon interference behavior is altered accordingly since this extra intrinsic phase affects the unitary of transformation and the coalescence of the incoming photons.We calculate the coincidence between two single-photon pulses,considering the interferometric phase between two pulses and the extra intrinsic phase as the tunable parameters.The extra phase turns the famous Hong–Ou–Mandel dip into a bump,with the visibility dependent on both the interferometric phase and the extra phase.展开更多
We report the Hong–Ou–Mandel（HOM） interference, with visibility of 91%, produced from two independent single photons retrieved from collective atomic excitations in two separate cold-atom clouds with high optical ...We report the Hong–Ou–Mandel（HOM） interference, with visibility of 91%, produced from two independent single photons retrieved from collective atomic excitations in two separate cold-atom clouds with high optical depths of 90. The high visibility of the HOM dip is ascribed to the pure single photon in the Fock state that was generated from a dense-cold-atom cloud pumping by a short pulse. The visibility is always the same regardless of the time response of the single-photon detectors. This result experimentally shows that the single photons retrieved are in a separable temporal state with their idler photons.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074171,12074168,92265109,and 12204227)the Key Laboratory Fund from Guangdong Province,China(Grant No.2019B121203002)the Natural Science Foundation of Guangdong Province,China(Grant Nos.2022B1515020096 and 2019ZT08X324).
文摘Temperature,as a measure of thermal motion,is a significant parameter characterizing a cold atomic ensemble optical quantum memory.In a cold gas,storage lifetime strongly depends on its temperature and is associated with the spin wave decoherence.Here we experimentally demonstrate a new spin wave thermometry method relying on this direct dependence.The short-wavelength spin waves resulting from the counter-propagating configuration of the control and the probe laser beams make this thermometry highly suitable for probing in situ the atomic motion in elongated clouds as the ones used in quantum memories.Our technique is realized with comparable precision for memories that rely on electromagnetically induced transparency as well as far-detuned Raman storage.
基金Supported by the National Science Foundation of China under Grant No 60471023, and the Science and Technology Plan of Guangdong Province under Grant No 2002A1060405.
文摘As proposed by Herminghaus, a hierarchical structure could render any surface nonwettable as long as the roughness amplitude at small scales is sufficient to suspend a free liquid surface. Recently we reported that the wettability of La0.7Sr0.3MnO3, an intrinsic hydrophilic oxide, can be tuned from superhydrophilicity to superhydrophobicity by hierarchical microstructures generated by annealing the coatings of La0.7Sr0.3MnO3 powder in nanometric scale at different temperatures. Here we further demonstrate the similar phenomenon observed on LaMaO3 coatings, which conforms THAT the surface geometrical structure is a key factor to determine the wettability.
基金Supported by the National Natural Science Foundation of China under Grant Nos 91436211 and 11204086the National Basic Research Program of China under Grant No 2011CB921604the Shanghai Science and Technology Committee under Grant No 13PJ1402100
文摘We present a cold atom system with a dark-line two-dimensional magneto-optical trap, to increase the atomic density by suppressing the atomic radiation pressure. Optical depth （OD） and duty cycle are used to evaluate the system performance. We demonstrate a 100% increase in OD with the dark line, and obtain an ultrahigh OD of 264 with 10% for the duty cycle. Also, with an efficient dark line region, the OD could maintain above i00 with duty cycle as high as 30%. The cold atomic ensemble with an ultrahigh OD with a 10%-30% duty cycle is particularly advantageous in quantum i^formation processing and communication.
基金the National Natural Science Foundation of China(Grant No.12074171)the Guangdong Key Project(Grant No.2019ZT08X324)+1 种基金the Guangdong Innovation Project(Grant No.2019KTSCX160)Guangdong Provincial Key Laboratory(Grant No.2019B121203002)。
文摘A photon source with high-dimensional entanglement is able to bring increasing capacity of information in quantum communication.The dimensionality is determined by the chosen degree of freedom of the photons and is limited by the complexity of the physical systems.Here we propose a new type of high-dimensional entangled photon source,generated via path-indistinguishable scheme from a two-dimensional atomic cloud,which is prepared in a magneto-optical trap.To verify the photon source,we demonstrate experimentally the quantum state of the single photons heralded by its partner photon,with homodyne tomographic technology.
基金Supported by the National Natural Science Foundation of China(Grant Nos.11674100 and 11654005)the Natural Science Foundation of Shanghai(Grant No.16ZR1448200)the Shanghai Rising-Star Program(Grant No.17QA1401300).
文摘We investigate photon coalescence in a lossy non-Hermitian system and study a dynamic device modeled by a beam splitter with an extra intrinsic phase term added in the transformation matrix,with which the device is a lossy non-Hermitian linear system.The two-photon interference behavior is altered accordingly since this extra intrinsic phase affects the unitary of transformation and the coalescence of the incoming photons.We calculate the coincidence between two single-photon pulses,considering the interferometric phase between two pulses and the extra intrinsic phase as the tunable parameters.The extra phase turns the famous Hong–Ou–Mandel dip into a bump,with the visibility dependent on both the interferometric phase and the extra phase.
基金supported by National 973 Program of China(No.2011CB921604)the National Natural Science Foundation of China(NSFC)through the major research plan(Precision Measurement Physics Grant No.91436211)+1 种基金the NSFC Key Research Program(No.11234003)the Young Scientists Research Program(No.11204086)
文摘We report the Hong–Ou–Mandel（HOM） interference, with visibility of 91%, produced from two independent single photons retrieved from collective atomic excitations in two separate cold-atom clouds with high optical depths of 90. The high visibility of the HOM dip is ascribed to the pure single photon in the Fock state that was generated from a dense-cold-atom cloud pumping by a short pulse. The visibility is always the same regardless of the time response of the single-photon detectors. This result experimentally shows that the single photons retrieved are in a separable temporal state with their idler photons.
