Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.Howe...Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.展开更多
Cryogenic oxide-confined vertical-cavity surface-emitting laser(VCSEL)has promising application in cryogenic optical interconnect for cryogenic computing.In this paper,we demonstrate a cryogenic 850-nm oxide-confined ...Cryogenic oxide-confined vertical-cavity surface-emitting laser(VCSEL)has promising application in cryogenic optical interconnect for cryogenic computing.In this paper,we demonstrate a cryogenic 850-nm oxide-confined VCSEL at around 4 K.The cryogenic VCSEL with an optical oxide aperture of 6.5μm in diameter can operate in single fundamental mode with a side-mode suppression-ratio of 36 dB at 3.6 K,and the fiber-coupled output power reaches 1 mW at 5 mA.The small signal modulation measurements at 298 and 292 K show the fabricated VCSEL has the potential to achieve a high modulation bandwidth at cryogenic temperature.展开更多
A silicon shallow-ridge waveguide integrated superconducting nanowire single photon detector is designed and fabricated.At the bias current of 11.6μA,4% on-chip detection efficiency near 1550 nm wavelength is achieve...A silicon shallow-ridge waveguide integrated superconducting nanowire single photon detector is designed and fabricated.At the bias current of 11.6μA,4% on-chip detection efficiency near 1550 nm wavelength is achieved with the dark count rate of 3 Hz and a timing jitter of 75 ps.This device shows the potential application in the integration of superconducting nanowire single photon detectors with a complex quantum photonic circuit.展开更多
A cold preamplifier based on superconducting quantum interference devices(SQUIDs)is currently the preferred readout technology for the low-noise transition edge sensor(TES).In this work,we have designed and fabricated...A cold preamplifier based on superconducting quantum interference devices(SQUIDs)is currently the preferred readout technology for the low-noise transition edge sensor(TES).In this work,we have designed and fabricated a series SQUID array(SSA)amplifier for the TES detector readout circuit.In this SSA amplifier,each SQUID cell is composed of a first-order gradiometer formed using two equally large square washers,and an on-chip low pass filter(LPF)as a radiofrequency(RF)choke has been developed to reduce the Josephson oscillation interference between individual SQUID cells.In addition,a highly symmetric layout has been designed carefully to provide a fully consistent embedded electromagnetic environment and achieve coherent flux operation.The measured results show smooth V-Φcharacteristics and a swing voltage that increases linearly with increasing SQUID cell number N.A white flux noise level as low as 0.28μφ;/Hz;is achieved at 0.1 K,corresponding to a low current noise level of 7 pA/Hz;.We analyze the measured noise contribution at mK-scale temperatures and find that the dominant noise derives from a combination of the SSA intrinsic noise and the equivalent current noise of the room temperature electronics.展开更多
We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper crit...We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper critical field(Hc2)in parallel to surface orientation shows bending curvature close to critical temperature Tc,suggesting a two-dimensional(2D)nature of the samples.The 2D behavior is further supported by the angular dependence measurements of Hc2 for the thinnest samples.The temperature dependence of parallel upper critical field for the thick films could be described by a model based on the anisotropic Ginzburg-Landau theory.Interestingly,the results measured in the field perpendicular to the film surface orientation show a similar bending curvature but in a much narrow temperature region close to Tc for the ultra-thin samples.We suggest that this feature could be due to suppression of pair-breaking caused by local in-homogeneity.We further propose the temperature dependence of perpendicular Hc2 as a measure of uniformity of superconducting ultra-thin films.For the thick samples,we find that Hc2 shows maxima for both parallel and perpendicular orientations.The Hc2 peak for the perpendicular orientation is believed to be due to the columnar structure formed during the growth of the thick films.The presence of columnar structure is confirmed by transmission electron microscopy(TEM).In addition,we have measured the angular dependence of magneto-resistance,and the results are consistent with the Hc2 data.展开更多
On-chip superconducting nanowire single-photon detectors(SNSPDs)are gaining traction in integrated quantum photonics due to their exceptional performance and the elimination of fiber coupling loss.However,off-chip hig...On-chip superconducting nanowire single-photon detectors(SNSPDs)are gaining traction in integrated quantum photonics due to their exceptional performance and the elimination of fiber coupling loss.However,off-chip high-rejection filters are commonly required to remove the intense pump light employed in quantum states generation,thus remaining the obstacle for embedding SNSPDs into quantum photonic circuits.Here,we explore the integration of SNSPDs with passive pump rejection filters,achieved by cascaded silicon Bragg gratings,on a single substrate.Serving as an entanglement receiver chip,the integrated components show a system detection efficiency of 20.1%and a pump rejection ratio of approximately 56 dB.We successfully verify energy-time entangled photon pairs from a microring resonator with raw visibilities of 92.85%±5.95%and 91.91%±7.34%under two nonorthogonal bases,with use of standard fiber wavelength demultiplexers.Our results pave the way for entanglement resource distribution,offering a promising approach toward the construction of large-scale quantum photonic systems.展开更多
Quantum teleportation is a crucial function in quantum networks.The implementation of photonic quantum teleportation could be highly simplified by quantum photonic circuits.To extend chip-to-chip teleportation distanc...Quantum teleportation is a crucial function in quantum networks.The implementation of photonic quantum teleportation could be highly simplified by quantum photonic circuits.To extend chip-to-chip teleportation distance,more effort is needed on both chip design and system implementation.In this work,we demonstrate a time-bin-based chip-to-chip photonic quantum teleportation over optical fibers under the scenario of a star-topology quantum network.Three quantum photonic circuits are designed and fabricated on a single chip,each serving specific functions:heralded single-photon generation at the user node,entangled photon pair generation and BSM at the relay node,and projective measurement of the teleported photons at the central node.The unbalanced Mach-Zehnder interferometers(UMZI)for time-bin encoding in these quantum photonic circuits are optimized to reduce insertion losses and suppress noise photons generated on the chip.Besides,an active feedback system is employed to suppress the impact of fiber length fluctuation between the circuits,achieving a stable quantum interference for the BSM in the relay node.As a result,a photonic quantum teleportation over optical fibers of 12.3 km is achieved based on these quantum photonic circuits,showing the potential ofchip integration for the development of quantum networks.展开更多
In this study,we investigate the impact of substrates with distributed Bragg reflectors(DBRs)on the proximity effect during the fabrication of superconducting nanowire single-photon detectors(SNSPDs)using electron bea...In this study,we investigate the impact of substrates with distributed Bragg reflectors(DBRs)on the proximity effect during the fabrication of superconducting nanowire single-photon detectors(SNSPDs)using electron beam lithography.We compare the linewidth compression and line edge roughness of nanowires prepared on three different DBRs substrates.Additionally,we characterize the variations in switching current(I_(sw))and intrinsic detection efficiency(IDE)at a 2.2-K temperature.The results show that when the substrates are composed of low atomic number materials,such as Si and SiO2,the proximity effect is significantly mitigated.As a consequence,the lithography quality of nanowires is effectively improved,thus enhancing the IDE of SNSPDs.This study is expected to provide new insights into the fabrication of SNSPDs and lay the foundation for the preparation of high-performance and high-uniformity large-area devices.展开更多
We report a broadband energy-time entangled photon-pair source based on a fiber-pigtailed periodically poled lithium niobate[PPLN]waveguide,designed for applications in the quantum secure network.Utilizing the spontan...We report a broadband energy-time entangled photon-pair source based on a fiber-pigtailed periodically poled lithium niobate[PPLN]waveguide,designed for applications in the quantum secure network.Utilizing the spontaneous parametric down-conversion nonlinear optical process,the source generates entangled photon pairs within a wavelength range of64 nm in the telecom band at a pump wavelength of 770.3 nm.Photon pairs from eight paired International Telecommunication Union[ITU]channels are selected,and their correlation and entanglement properties are characterized.The measured coincidence counts of photon pairs from eight paired ITU channels are larger than 152.9 kHz when the coincidence-to-accidental ratios are greater than 260.Entanglement properties are measured through two-photon interference in the Franson interferometer,with all visibilities of interference curves exceeding 98.13%.Our demonstration provides a broadband energy-time entangled photon-pair source,contributing to the development of a large-scale quantum secure network.展开更多
In this study,we present a comprehensive thermo-optic characterization of an on-chip thin-film lithium niobate asymmetric Mach-Zehnder interferometer(aMZI)across a temperature range of 290 to 10 K.We observe that the ...In this study,we present a comprehensive thermo-optic characterization of an on-chip thin-film lithium niobate asymmetric Mach-Zehnder interferometer(aMZI)across a temperature range of 290 to 10 K.We observe that the spectral shift of the aMZI is closely associated with changes in the environmental temperature.We experimentally observed a 4.88 nm wavelength shift of the a MZI from 290 to 10 K.Moreover,the shift diminished gradually below 50 K.Our observations highlight a distinctive non-linear temperature sensitivity,particularly pronounced at cryogenic temperatures.The high-resolution setup revealed a thermo-optic coefficient as low as 5.29×10^(-8)K^(-1)at 10 K.The presented results provide new practical guidelines for designing photonic circuits for applications in cryogenic optoelectronics.展开更多
Rapid detection and discrimination of single photons are pivotal in various applications,such as deep-space laser communication,high-rate quantum key distribution,and optical quantum computation.However,conventional s...Rapid detection and discrimination of single photons are pivotal in various applications,such as deep-space laser communication,high-rate quantum key distribution,and optical quantum computation.However,conventional single-photon detectors(SPDs),including semiconducting and recently developed superconducting detectors,have limited detection speed and photon number resolution(PNR),which pose significant challenges in practical applications.In this paper,we present an efficient,fast SPD with good PNR,which has 64 paralleled,sandwiched superconducting nanowires fabricated on a distributed Bragg reflector.The detector is operated in a compact Gifford–McMahon cryocooler that supports 64 electrical channels and has a minimum working temperature of 2.3 K.The combined detector system shows a functional nanowire yield of 61/64,a system detection efficiency of 90%at 1550 nm,and a maximum count rate of 5.2 GHz.Additionally,it has a maximum PNR of 61,corresponding to the operating nanowires.This SPD signifies a substantial improvement in quantum detector technology,with potential applications in deep-space laser communication,high-speed quantum communication,and fundamental quantum optics experiments.展开更多
We systematically investigated the detection performance of Al nanostrips for single photons at various wavelengths.The Al films were deposited using magnetron sputtering,and the sophisticated nanostructures and morph...We systematically investigated the detection performance of Al nanostrips for single photons at various wavelengths.The Al films were deposited using magnetron sputtering,and the sophisticated nanostructures and morphology of the deposited films were revealed through high-resolution transmission electron microscopy.The fabricated Al meander nanostrips,with a thickness of 4.2 nm and a width of 178 nm,exhibited a superconducting transition temperature of 2.4 K and a critical current of approximately 5μA at 0.85 K.While the Al nanostrips demonstrated a saturated internal quantum efficiency for 405-nm photons,the internal detection efficiency exhibited an exponential dependence on bias current without any saturation tendency for 1550-nm photons.This behavior can be attributed to the relatively large diffusion coefficient and coherence length of the Al films.By further narrowing the nanostrip width,the Al-SNSPDs remain capable of effectively detecting single telecom photons to facilitate practical applications.展开更多
The light–matter interface is an important building block for long-distance quantum networks.Towards a scalable quantum network with high-rate quantum information processing,it requires to develop integrated light–m...The light–matter interface is an important building block for long-distance quantum networks.Towards a scalable quantum network with high-rate quantum information processing,it requires to develop integrated light–matter interfaces with broadband and multiplexing capacities.Here we demonstrate a light–matter interface at the telecom band in an integrated system.A five-spectral-channel atomic-frequency-comb photonic memory is prepared on a laser-written Er^(3+):LiNbO_(3)chip.The bandwidth of each channel is 4 GHz with a channel spacing of 15 GHz.The signal photons from time-bin entangled photon pairs at the telecom band are sent into the on-chip memory and recalled after a storage time of 152 ns.The entanglement-preserving nature of our integrated quantum interface is assessed by an input/output fidelity of>92%for all five spectral channels.Our light–matter interfaces constitute a notable step forward toward a high-rate quantum network involving integrated devices.展开更多
Quantum photonic integrated circuits offer enhanced stability and scalability for quantum communications,sensing, and computing. Transverse modes in multimode waveguides enable high-dimensional scalability and versati...Quantum photonic integrated circuits offer enhanced stability and scalability for quantum communications,sensing, and computing. Transverse modes in multimode waveguides enable high-dimensional scalability and versatile photon manipulation, but practical adoption requires compact and fabrication-tolerant quantum interference devices. Here, we present an ultra-compact taper-stepped beamsplitter that enables quantum interference between photon pairs in different transverse modes, and cascade it to realize NOON state interferometry. We experimentally achieve high visibilities of 93.9% for HOM interference and 86.5% for NOON state interference,demonstrating that efficient mode interference with active tuning can be realized on this platform.展开更多
Spectroscopy is a well-established nonintrusive tool that has played an important role in identifying and quantifying substances,from quantum descriptions to chemical and biomedical diagnostics.Challenges exist in acc...Spectroscopy is a well-established nonintrusive tool that has played an important role in identifying and quantifying substances,from quantum descriptions to chemical and biomedical diagnostics.Challenges exist in accurate spectrum analysis in free space,which hinders us from understanding the composition of multiple gases and the chemical processes in the atmosphere.A photon-counting distributed free-space spectroscopy is proposed and demonstrated using lidar technique,incorporating a comb-referenced frequency-scanning laser and a superconducting nanowire single-photon detector.It is suitable for remote spectrum analysis with a range resolution over a wide band.As an example,a continuous field experiment is carried out over 72 h to obtain the spectra of carbon dioxide(CO_(2))and semi-heavy water(HDO,isotopic water vapor)in 6 km,with a range resolution of 60 m and a time resolution of 10 min.Compared to the methods that obtain only column-integrated spectra over kilometer-scale,the range resolution is improved by 2-3 orders of magnitude in this work.The CO_(2)and HDO concentrations are retrieved from the spectra acquired with uncertainties as low as±1.2%and±14.3%,respectively.This method holds much promise for increasing knowledge of atmospheric environment and chemistry researches,especially in terms of the evolution of complex molecular spectra in open areas.展开更多
Gaussian Boson sampling(GBS) provides a highly efficient approach to make use of squeezed states from parametric down-conversion to solve a classically hard-to-solve sampling problem. The GBS protocol not only signifi...Gaussian Boson sampling(GBS) provides a highly efficient approach to make use of squeezed states from parametric down-conversion to solve a classically hard-to-solve sampling problem. The GBS protocol not only significantly enhances the photon generation probability, compared to standard Boson sampling with single photon Fock states, but also links to potential applications such as dense subgraph problems and molecular vibronic spectra. Here, we report the first experimental demonstration of GBS using squeezed-state sources with simultaneously high photon indistinguishability and collection efficiency.We implement and validate 3-, 4- and 5-photon GBS with high sampling rates of 832, 163 and 23 kHz,respectively, which is more than 4.4, 12.0, and 29.5 times faster than the previous experiments.Further, we observe a quantum speed-up on a NP-hard optimization problem when comparing with simulated thermal sampler and uniform sampler.展开更多
Quantum teleportation can transfer an unknown quantum state between distant quantum nodes,which holds great promise in enabling large-scale quantum networks.To advance the full potential of quantum teleportation,quant...Quantum teleportation can transfer an unknown quantum state between distant quantum nodes,which holds great promise in enabling large-scale quantum networks.To advance the full potential of quantum teleportation,quantum states must be faithfully transferred at a high rate over long distance.Despite recent impressive advances,a high-rate quantum teleportation system across metropolitan fiber networks is extremely desired.Here,we demonstrate a quantum teleportation system which transfers quantum states carried by independent photons at a rate of 7.1±0.4 Hz over 64-km-long fiber channel.An average single-photon fidelity of≥90.6±2.6%is achieved,which exceeds the maximum fidelity of 2/3 in classical regime.Our result marks an important milestone towards quantum networks and opens the door to exploring quantum entanglement based informatic applications for the future quantum internet.展开更多
The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an ...The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an incident photon wavelength of 1550 nm is 93%. This performance was attained from a superconducting nanowire single-photon detector made of amorphous WSi; such detectors are usually operated at sub-Kelvin temperatures. In this study, we first demonstrate superconducting nanowire single-photon detectors made of polycrystalline NbN with system detection efficiency of 90.2% for 1550-nm-wavelength photons at2.1 K, accessible with a compact cryocooler. The system detection efficiency saturated at 92.1% when the temperature was lowered to 1.8 K. We expect the results lighten the practical and high performance superconducting nanowire single-photon detectors to quantum information and other high-end applications.展开更多
基金the Innovation Program for Quantum Science and Technology(Grant No.2023ZD0300100)the National Key Research and Development Program of China(Grant Nos.2023YFB3809600 and 2023YFC3007801)+1 种基金the National Natural Science Foundation of China(Grant Nos.62301543 and U24A20320)the Shanghai Sailing Program(Grant No.21YF1455700).
文摘Conventional superconducting nanowire single-photon detectors(SNSPDs)have been typically limited in their applications due to their size,weight,and power consumption,which confine their use to laboratory settings.However,with the rapid development of remote imaging,sensing technologies,and long-range quantum communication with fewer topographical constraints,the demand for high-efficiency single-photon detectors integrated with avionic platforms is rapidly growing.We herein designed and manufactured the first drone-based SNSPD system with a system detection efficiency(SDE)as high as 91.8%.This drone-based system incorporates high-performance NbTiN SNSPDs,a self-developed miniature liquid helium dewar,and custom-built integrated electrical setups,making it capable of being launched in complex topographical conditions.Such a drone-based SNSPD system may open the use of SNSPDs for applications that demand high SDE in complex environments.
基金supported by the National Natural Science Foundation of China(Nos.62275243,62075209,and 61675193)the Beijing Natural Science Foundation(No.Z200006).
文摘Cryogenic oxide-confined vertical-cavity surface-emitting laser(VCSEL)has promising application in cryogenic optical interconnect for cryogenic computing.In this paper,we demonstrate a cryogenic 850-nm oxide-confined VCSEL at around 4 K.The cryogenic VCSEL with an optical oxide aperture of 6.5μm in diameter can operate in single fundamental mode with a side-mode suppression-ratio of 36 dB at 3.6 K,and the fiber-coupled output power reaches 1 mW at 5 mA.The small signal modulation measurements at 298 and 292 K show the fabricated VCSEL has the potential to achieve a high modulation bandwidth at cryogenic temperature.
基金Supported by the National Key R&D Program of China under Grant Nos 2017YFA0303704 and 2017YFA0304000the National Natural Science Foundation of China under Grant Nos 61575102,91750206,61671438,61875101 and 61621064+1 种基金the Beijing Natural Science Foundation under Grant No Z180012the Beijing Academy of Quantum Information Sciences under Grant No Y18G26
文摘A silicon shallow-ridge waveguide integrated superconducting nanowire single photon detector is designed and fabricated.At the bias current of 11.6μA,4% on-chip detection efficiency near 1550 nm wavelength is achieved with the dark count rate of 3 Hz and a timing jitter of 75 ps.This device shows the potential application in the integration of superconducting nanowire single photon detectors with a complex quantum photonic circuit.
基金supported by the National Key Research and Development Program of China(Grant No.2017YFA0304003)。
文摘A cold preamplifier based on superconducting quantum interference devices(SQUIDs)is currently the preferred readout technology for the low-noise transition edge sensor(TES).In this work,we have designed and fabricated a series SQUID array(SSA)amplifier for the TES detector readout circuit.In this SSA amplifier,each SQUID cell is composed of a first-order gradiometer formed using two equally large square washers,and an on-chip low pass filter(LPF)as a radiofrequency(RF)choke has been developed to reduce the Josephson oscillation interference between individual SQUID cells.In addition,a highly symmetric layout has been designed carefully to provide a fully consistent embedded electromagnetic environment and achieve coherent flux operation.The measured results show smooth V-Φcharacteristics and a swing voltage that increases linearly with increasing SQUID cell number N.A white flux noise level as low as 0.28μφ;/Hz;is achieved at 0.1 K,corresponding to a low current noise level of 7 pA/Hz;.We analyze the measured noise contribution at mK-scale temperatures and find that the dominant noise derives from a combination of the SSA intrinsic noise and the equivalent current noise of the room temperature electronics.
基金the Chinese Academy of Sciences(Grant No.XDB25000000).
文摘We study superconducting properties of NbN thin film samples with different thicknesses and an ultra-thin NbTiN meander nanowire sample.For the ultra-thin samples,we found that the temperature dependence of upper critical field(Hc2)in parallel to surface orientation shows bending curvature close to critical temperature Tc,suggesting a two-dimensional(2D)nature of the samples.The 2D behavior is further supported by the angular dependence measurements of Hc2 for the thinnest samples.The temperature dependence of parallel upper critical field for the thick films could be described by a model based on the anisotropic Ginzburg-Landau theory.Interestingly,the results measured in the field perpendicular to the film surface orientation show a similar bending curvature but in a much narrow temperature region close to Tc for the ultra-thin samples.We suggest that this feature could be due to suppression of pair-breaking caused by local in-homogeneity.We further propose the temperature dependence of perpendicular Hc2 as a measure of uniformity of superconducting ultra-thin films.For the thick samples,we find that Hc2 shows maxima for both parallel and perpendicular orientations.The Hc2 peak for the perpendicular orientation is believed to be due to the columnar structure formed during the growth of the thick films.The presence of columnar structure is confirmed by transmission electron microscopy(TEM).In addition,we have measured the angular dependence of magneto-resistance,and the results are consistent with the Hc2 data.
基金Innovation Program for Quantum Science and Technology(2023ZD0300100)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)+1 种基金National Natural Science Foundation of China(61971408,12033007,92365210,U24A20320)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020241,2021230)。
文摘On-chip superconducting nanowire single-photon detectors(SNSPDs)are gaining traction in integrated quantum photonics due to their exceptional performance and the elimination of fiber coupling loss.However,off-chip high-rejection filters are commonly required to remove the intense pump light employed in quantum states generation,thus remaining the obstacle for embedding SNSPDs into quantum photonic circuits.Here,we explore the integration of SNSPDs with passive pump rejection filters,achieved by cascaded silicon Bragg gratings,on a single substrate.Serving as an entanglement receiver chip,the integrated components show a system detection efficiency of 20.1%and a pump rejection ratio of approximately 56 dB.We successfully verify energy-time entangled photon pairs from a microring resonator with raw visibilities of 92.85%±5.95%and 91.91%±7.34%under two nonorthogonal bases,with use of standard fiber wavelength demultiplexers.Our results pave the way for entanglement resource distribution,offering a promising approach toward the construction of large-scale quantum photonic systems.
基金supported by the National Natural Science Foundation of China(92365210,W.Z.)the National Key R&D Program of China(2023YFB2806700,Y.H.)+2 种基金the Innovation Program for Quantum Science and Technology(2023ZD0300100,L.Y.)the Tsinghua Initiative Scientific Research Program(W.Z.)the project of Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies(JIAOT,Y.H.)。
文摘Quantum teleportation is a crucial function in quantum networks.The implementation of photonic quantum teleportation could be highly simplified by quantum photonic circuits.To extend chip-to-chip teleportation distance,more effort is needed on both chip design and system implementation.In this work,we demonstrate a time-bin-based chip-to-chip photonic quantum teleportation over optical fibers under the scenario of a star-topology quantum network.Three quantum photonic circuits are designed and fabricated on a single chip,each serving specific functions:heralded single-photon generation at the user node,entangled photon pair generation and BSM at the relay node,and projective measurement of the teleported photons at the central node.The unbalanced Mach-Zehnder interferometers(UMZI)for time-bin encoding in these quantum photonic circuits are optimized to reduce insertion losses and suppress noise photons generated on the chip.Besides,an active feedback system is employed to suppress the impact of fiber length fluctuation between the circuits,achieving a stable quantum interference for the BSM in the relay node.As a result,a photonic quantum teleportation over optical fibers of 12.3 km is achieved based on these quantum photonic circuits,showing the potential ofchip integration for the development of quantum networks.
基金Innovation Program for Quantum Science and Technology(No.2023ZD0300100)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)National Natural Science Foundation of China(U24A20320,and 12033007)for their financial support.
文摘In this study,we investigate the impact of substrates with distributed Bragg reflectors(DBRs)on the proximity effect during the fabrication of superconducting nanowire single-photon detectors(SNSPDs)using electron beam lithography.We compare the linewidth compression and line edge roughness of nanowires prepared on three different DBRs substrates.Additionally,we characterize the variations in switching current(I_(sw))and intrinsic detection efficiency(IDE)at a 2.2-K temperature.The results show that when the substrates are composed of low atomic number materials,such as Si and SiO2,the proximity effect is significantly mitigated.As a consequence,the lithography quality of nanowires is effectively improved,thus enhancing the IDE of SNSPDs.This study is expected to provide new insights into the fabrication of SNSPDs and lay the foundation for the preparation of high-performance and high-uniformity large-area devices.
基金supported by the Sichuan Science and Technology Program(Nos.2022YFSY0061,2023YFSY0061,2022YFSY0062,2022YFSY0063,2023YFSY0058,and2023YFSY0060)the National Natural Science Foundation of China(Nos.62405046,62475039,and 92365106)+1 种基金the Innovation Program for Quantum Science and Technology(No.2021ZD0301702)the Tianfu Jiangxi Laboratory(No.TFJX-ZD-2024-002)。
文摘We report a broadband energy-time entangled photon-pair source based on a fiber-pigtailed periodically poled lithium niobate[PPLN]waveguide,designed for applications in the quantum secure network.Utilizing the spontaneous parametric down-conversion nonlinear optical process,the source generates entangled photon pairs within a wavelength range of64 nm in the telecom band at a pump wavelength of 770.3 nm.Photon pairs from eight paired International Telecommunication Union[ITU]channels are selected,and their correlation and entanglement properties are characterized.The measured coincidence counts of photon pairs from eight paired ITU channels are larger than 152.9 kHz when the coincidence-to-accidental ratios are greater than 260.Entanglement properties are measured through two-photon interference in the Franson interferometer,with all visibilities of interference curves exceeding 98.13%.Our demonstration provides a broadband energy-time entangled photon-pair source,contributing to the development of a large-scale quantum secure network.
基金supported by the Innovation Program for Quantum Science and Technology(No.2023ZD0300100)the Shanghai Municipal Science and Technology Major Project(Nos.2019SHZDZX01 and 2017SHZDZX03)+1 种基金the Strategic Priority Research Program(A)of the Chinese Academy of Sciences(No.XDA18040300)the ShanghaiTech University(Start-up funding)。
文摘In this study,we present a comprehensive thermo-optic characterization of an on-chip thin-film lithium niobate asymmetric Mach-Zehnder interferometer(aMZI)across a temperature range of 290 to 10 K.We observe that the spectral shift of the aMZI is closely associated with changes in the environmental temperature.We experimentally observed a 4.88 nm wavelength shift of the a MZI from 290 to 10 K.Moreover,the shift diminished gradually below 50 K.Our observations highlight a distinctive non-linear temperature sensitivity,particularly pronounced at cryogenic temperatures.The high-resolution setup revealed a thermo-optic coefficient as low as 5.29×10^(-8)K^(-1)at 10 K.The presented results provide new practical guidelines for designing photonic circuits for applications in cryogenic optoelectronics.
基金Innovation Program for Quantum Science and Technology(2023ZD0300100)Shanghai Sailing Program(21YF1455500,21YF1455700,22YF1456500)+2 种基金Youth Innovation Promotion Association of the Chinese Academy of Sciences(2020241,2021230)Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)National Natural Science Foundation of China(12033007,61827823,61971408).
文摘Rapid detection and discrimination of single photons are pivotal in various applications,such as deep-space laser communication,high-rate quantum key distribution,and optical quantum computation.However,conventional single-photon detectors(SPDs),including semiconducting and recently developed superconducting detectors,have limited detection speed and photon number resolution(PNR),which pose significant challenges in practical applications.In this paper,we present an efficient,fast SPD with good PNR,which has 64 paralleled,sandwiched superconducting nanowires fabricated on a distributed Bragg reflector.The detector is operated in a compact Gifford–McMahon cryocooler that supports 64 electrical channels and has a minimum working temperature of 2.3 K.The combined detector system shows a functional nanowire yield of 61/64,a system detection efficiency of 90%at 1550 nm,and a maximum count rate of 5.2 GHz.Additionally,it has a maximum PNR of 61,corresponding to the operating nanowires.This SPD signifies a substantial improvement in quantum detector technology,with potential applications in deep-space laser communication,high-speed quantum communication,and fundamental quantum optics experiments.
基金Strategic Priority Research Program(B)of the Chinese Academy of Sciences(XDB0580000)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021230)+2 种基金Shanghai Science and Technology Development Foundation(21YF1455500)Science and Technology Commission of Shanghai Municipality(2019SHZDZX01)National Natural Science Foundation of China(61801462,61827823,61971408).
文摘We systematically investigated the detection performance of Al nanostrips for single photons at various wavelengths.The Al films were deposited using magnetron sputtering,and the sophisticated nanostructures and morphology of the deposited films were revealed through high-resolution transmission electron microscopy.The fabricated Al meander nanostrips,with a thickness of 4.2 nm and a width of 178 nm,exhibited a superconducting transition temperature of 2.4 K and a critical current of approximately 5μA at 0.85 K.While the Al nanostrips demonstrated a saturated internal quantum efficiency for 405-nm photons,the internal detection efficiency exhibited an exponential dependence on bias current without any saturation tendency for 1550-nm photons.This behavior can be attributed to the relatively large diffusion coefficient and coherence length of the Al films.By further narrowing the nanostrip width,the Al-SNSPDs remain capable of effectively detecting single telecom photons to facilitate practical applications.
基金Sichuan Science and Technology Program(2022YFSY0061,2022YFSY0062,2022YFSY0063,2023YFSY0058,2023NSFSC0048)Innovation Program for Quantum Science and Technology(2021ZD0301702)+2 种基金National Natural Science Foundation of China(12174222,62475039,62405046)Natural Science Foundation of Shandong Province(ZR2021ZD02)National Key Research and Development Program of China(2018YFA0306102,2022YFA1405900).
文摘The light–matter interface is an important building block for long-distance quantum networks.Towards a scalable quantum network with high-rate quantum information processing,it requires to develop integrated light–matter interfaces with broadband and multiplexing capacities.Here we demonstrate a light–matter interface at the telecom band in an integrated system.A five-spectral-channel atomic-frequency-comb photonic memory is prepared on a laser-written Er^(3+):LiNbO_(3)chip.The bandwidth of each channel is 4 GHz with a channel spacing of 15 GHz.The signal photons from time-bin entangled photon pairs at the telecom band are sent into the on-chip memory and recalled after a storage time of 152 ns.The entanglement-preserving nature of our integrated quantum interface is assessed by an input/output fidelity of>92%for all five spectral channels.Our light–matter interfaces constitute a notable step forward toward a high-rate quantum network involving integrated devices.
基金supported by the National Key Research and Development Program of China (Grant No.2022YFB2803100)the National Major Scientific Research Instrument Development Project(Grant No.22127901)+6 种基金the National Natural Science Foundation of China (Grant No.62305367)the Shanghai Natural Science Foundation (Grant No.25ZR1401379)the Natural Science Foundation of Zhejiang Province,China (Grant No.LZ24F050001)the Innovation Program for Quantum Science and Technology (Grant Nos.2021ZD0301500 and 2021ZD0303200)the National Natural Science Foundation of China (Grant Nos.T2325022,U23A2074,62061160487,and 62275240)the CAS Project for Young Scientists in Basic Research(Grant No.YSBR-049)the Fundamental Research Funds for the Central Universities。
文摘Quantum photonic integrated circuits offer enhanced stability and scalability for quantum communications,sensing, and computing. Transverse modes in multimode waveguides enable high-dimensional scalability and versatile photon manipulation, but practical adoption requires compact and fabrication-tolerant quantum interference devices. Here, we present an ultra-compact taper-stepped beamsplitter that enables quantum interference between photon pairs in different transverse modes, and cascade it to realize NOON state interferometry. We experimentally achieve high visibilities of 93.9% for HOM interference and 86.5% for NOON state interference,demonstrating that efficient mode interference with active tuning can be realized on this platform.
基金This work was supported by The National Ten Thousand Talent Program in China.We are grateful to Nanjing Taixin Co.,Ltd.for financial support(91320191MA26A48Q5X).
文摘Spectroscopy is a well-established nonintrusive tool that has played an important role in identifying and quantifying substances,from quantum descriptions to chemical and biomedical diagnostics.Challenges exist in accurate spectrum analysis in free space,which hinders us from understanding the composition of multiple gases and the chemical processes in the atmosphere.A photon-counting distributed free-space spectroscopy is proposed and demonstrated using lidar technique,incorporating a comb-referenced frequency-scanning laser and a superconducting nanowire single-photon detector.It is suitable for remote spectrum analysis with a range resolution over a wide band.As an example,a continuous field experiment is carried out over 72 h to obtain the spectra of carbon dioxide(CO_(2))and semi-heavy water(HDO,isotopic water vapor)in 6 km,with a range resolution of 60 m and a time resolution of 10 min.Compared to the methods that obtain only column-integrated spectra over kilometer-scale,the range resolution is improved by 2-3 orders of magnitude in this work.The CO_(2)and HDO concentrations are retrieved from the spectra acquired with uncertainties as low as±1.2%and±14.3%,respectively.This method holds much promise for increasing knowledge of atmospheric environment and chemistry researches,especially in terms of the evolution of complex molecular spectra in open areas.
基金supported by the National Natural Science Foundation of China (91836303, 11674308, and 11525419)the Chinese Academy of Sciences, the National Fundamental Research Program (2018YFA0306100)the Anhui Initiative in Quantum Information Technologies
文摘Gaussian Boson sampling(GBS) provides a highly efficient approach to make use of squeezed states from parametric down-conversion to solve a classically hard-to-solve sampling problem. The GBS protocol not only significantly enhances the photon generation probability, compared to standard Boson sampling with single photon Fock states, but also links to potential applications such as dense subgraph problems and molecular vibronic spectra. Here, we report the first experimental demonstration of GBS using squeezed-state sources with simultaneously high photon indistinguishability and collection efficiency.We implement and validate 3-, 4- and 5-photon GBS with high sampling rates of 832, 163 and 23 kHz,respectively, which is more than 4.4, 12.0, and 29.5 times faster than the previous experiments.Further, we observe a quantum speed-up on a NP-hard optimization problem when comparing with simulated thermal sampler and uniform sampler.
基金This work was supported by the National Key Research and Development Program of China(Nos.2018YFA0307400,2018YFA0306102)National Natural Science Foundation of China(Nos.61775025,91836102,U19A2076,62005039)+1 种基金Innovation Program for Quantum Science and Technology(No.2021ZD0301702)Sichuan Science and Technology Program(Nos.2021YFSY0066,2021YFSY0062,2021YFSY0063,2021YFSY0064,2021YFSY0065).The authors thank X.X.H,Y.X.L and L.B.Z from the Information Center of the University of Electronic Science and Technology of China(UESTC)for providing access to the campus fiber network and for the help during the experiment.
文摘Quantum teleportation can transfer an unknown quantum state between distant quantum nodes,which holds great promise in enabling large-scale quantum networks.To advance the full potential of quantum teleportation,quantum states must be faithfully transferred at a high rate over long distance.Despite recent impressive advances,a high-rate quantum teleportation system across metropolitan fiber networks is extremely desired.Here,we demonstrate a quantum teleportation system which transfers quantum states carried by independent photons at a rate of 7.1±0.4 Hz over 64-km-long fiber channel.An average single-photon fidelity of≥90.6±2.6%is achieved,which exceeds the maximum fidelity of 2/3 in classical regime.Our result marks an important milestone towards quantum networks and opens the door to exploring quantum entanglement based informatic applications for the future quantum internet.
基金supported by the National Key R&D Program of China(Grant No.2017YFA0304000)Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB04010200)+1 种基金the National Natural Science Foundation of China(Grant Nos.91121022,61401441,and61401443)the Science and Technology Commission of Shanghai Municipality(Grant No.16JC1400402)
文摘The rapid development of superconducting nanowire single-photon detectors over the past decade has led to numerous advances in quantum information technology. The record for the best system detection efficiency at an incident photon wavelength of 1550 nm is 93%. This performance was attained from a superconducting nanowire single-photon detector made of amorphous WSi; such detectors are usually operated at sub-Kelvin temperatures. In this study, we first demonstrate superconducting nanowire single-photon detectors made of polycrystalline NbN with system detection efficiency of 90.2% for 1550-nm-wavelength photons at2.1 K, accessible with a compact cryocooler. The system detection efficiency saturated at 92.1% when the temperature was lowered to 1.8 K. We expect the results lighten the practical and high performance superconducting nanowire single-photon detectors to quantum information and other high-end applications.
