The Southern Advanced Photon Source(SAPS)is a diffraction-limited synchrotron light source under design,which employs longitudinal injection as its primary injection scheme.This kind of injection scheme requires that ...The Southern Advanced Photon Source(SAPS)is a diffraction-limited synchrotron light source under design,which employs longitudinal injection as its primary injection scheme.This kind of injection scheme requires that the injected beam has a short bunch length and low emittance,and the preferred injector should offer high stability and low cost.Therefore,an injector based on a booster synchrotron was developed.The proposed injector includes a 250 MeV linac,a booster synchrotron that ramps the beam energy to 3.5 GeV,and two beam transport lines to ensure efficient beam delivery and beam quality preservation.The linac utilizes a thermionic high-voltage DC gun for reliable operation and features a bunching system with an advanced focusing system to preserve the emittance.To meet the injection requirements of the SAPS,a comprehensive design for the booster has been conducted.The booster synchrotron employs a threefold lattice structure,incorporating modified theoretical minimum emittance cells with a small momentum compaction factor and a high voltage to achieve an emittance of 3.98 nm rad and a bunch length of 4.8 mm.The injector has the potential to deliver a high charge,reducing the injection period of the storage ring to less than 1 min.Simulations demonstrated the expected performance,with a transmission efficiency of 90%,confirming its capability to meet the injection requirement of the SAPS storage ring.This design offers a stable and efficient solution for the SAPS.展开更多
To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.T...To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.展开更多
The single-molecule detection tech-nique plays a pivotal role in elucidat-ing the fundamental mechanisms of various scientific processes at the molecular level,and holds essential im-portance in multiple fields includ...The single-molecule detection tech-nique plays a pivotal role in elucidat-ing the fundamental mechanisms of various scientific processes at the molecular level,and holds essential im-portance in multiple fields including physics,biology,and chemistry.Re-cently,single-molecule detection has garnered increasing attention owing to its practical utility in medical diagno-sis,primarily due to its exceptional sensitivity and the minimal sample volume required for analysis.However,the conventional single-molecule technique,represented by total internal reflection microscopy,faces challenges such as sophisticated operation procedures and limited detection throughput,thereby impeding its broader application.To address these limitations,we have demonstrated single-molecule detection using an integrated silicon photonic chip,of-fering a cost-effective and user-friendly alternative.By employing basic optics,we efficiently introduce the excitation source for single-molecule fluorescence by harnessing the strong evanescent field of high refractive-index waveguides.Subsequently,fluorescence signals are collected using basic optics comprising a water-immersion objective,relay optics,and a digi-tal camera.Our results highlight a low-cost,high-throughput single-molecule technique achieved through the integrated silicon photonic chip.This innovative approach is promised to facilitate the widespread adoption of single-molecule fluorescence in medical diagnosis.展开更多
This paper presents a three-dimensional particle-in-cell （PIC） simulation of a Ka-band relativistic Cherenkov source with a slow wave structure （SWS） consisting of metal photonic band gap （PBG） structures. In th...This paper presents a three-dimensional particle-in-cell （PIC） simulation of a Ka-band relativistic Cherenkov source with a slow wave structure （SWS） consisting of metal photonic band gap （PBG） structures. In the simulation, a perfect match layer boundary is employed to absorb passing band modes supported by the PBG lattice with an artificial metal boundary. The simulated axial field distributions in the cross section and surface of the SWS demonstrate that the device operates in the vicinity of the π point of a TM01-1ike mode. The Fourier transformation spectra of the axial fields as functions of time and space show that only a single frequency appears at 36.27 GHz, which is in good agreement with that of the intersection of the dispersion curve with the slow space charge wave generated on the beam. The simulation results demonstrate that the SWS has good mode selectivity.展开更多
Single photon sources are key components for quantum technologies such as quantum communication, computing and metrology. A key challenge towards the realization of global quantum networks are transmission losses in o...Single photon sources are key components for quantum technologies such as quantum communication, computing and metrology. A key challenge towards the realization of global quantum networks are transmission losses in optical fibers. Therefore, single photon sources are required to emit at the low-loss telecom wavelength bands. However, an ideal telecom wavelength single photon source has yet to be discovered. Here, we review the recent progress in realizing such sources. We start with single photon emission based on atomic ensembles and spontaneous parametric down conversion, and then focus on solid-state emitters including semiconductor quantum dots, defects in silicon carbide and carbon nanotubes. In conclusion, some state-of-the-art applications are highlighted.展开更多
Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal deco...Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal decoy state protocol with a heralded single photon source （HSPS） for QKD is presented. The protocol is based on 4 states with different intensities. i.e. one signal state and three decoy states. The signal state is for generating keys; the decoy states are for detecting the eavesdropping and estimating the fraction of single-photon and two-photon pulses. We have discussed three cases of this protocol, i.e. the general case, the optimal case and the special case. Moreover, the final key rate over transmission distance is simulated. For the low dark count of the HSPS and the utilization of the two-photon pulses, our protocol has a higher key rate and a longer transmission distance than any other decoy state protocol.展开更多
Single-photon sources are building blocks for photonic quantum information processes. Of the many single-photon generation schemes, electrically driven single-photon sources have the advantages of realizing monolithic...Single-photon sources are building blocks for photonic quantum information processes. Of the many single-photon generation schemes, electrically driven single-photon sources have the advantages of realizing monolithic integration of quantum light sources and detectors without optical filtering, thus greatly simplify the integrated quantum photonic circuits. Here, we review recent advances on electrically driven single-photon sources based on solid-state quantum emitters, such as semiconductor epitaxial quantum dots, colloidal quantum dots, carbon nanotubes, molecules, and defect states in diamond, SiC and layered semiconductors. In particular, the merits and drawbacks of each system are discussed. Finally, the article is concluded by discussing the challenges that remain for electrically driven single-photon sources.展开更多
The intrinsic characteristics of single photons became critical issues since the early development of quantum mechanics. Nowadays, acting as flying qubits, single photons are shown to play important roles in the quant...The intrinsic characteristics of single photons became critical issues since the early development of quantum mechanics. Nowadays, acting as flying qubits, single photons are shown to play important roles in the quantum key distribution and quantum networks. Many different single photon sources (SPSs) have been developed. Point defects in silicon carbide (SiC) have been shown to be promising SPS candidates in the telecom range. In this work, we demonstrate a stable SPS in an epitaxial 3CSiC with the wavelength in the near C-band range, which is very suitable for fiber communications. The observed SPSs show high single photon purity and stable fluorescence at even above 400 K. The lifetimes of the SPSs are found to be almost linearly decreased with the increase of temperature. Since the epitaxial 3C-SiC can be conveniently nanofabricated, these stable near Cband SPSs would find important applications in the integrated photonic devices.展开更多
We investigate metallic microdisk-size dependence of quantum dot （QD） spontaneous emission rate and micro- antenna directional emission effect for the hybrid metM-distributed Bragg reflector structures based on a pa...We investigate metallic microdisk-size dependence of quantum dot （QD） spontaneous emission rate and micro- antenna directional emission effect for the hybrid metM-distributed Bragg reflector structures based on a particular single QD emission. It is found that the measured photolumineseence （PL） intensity is very sensitive to the size of metMlic disk, showing an enhancement factor of 11 when the optimal disk diameter is 2μm and the numerical aperture of microscope objective NA=0.5. It is found that for large metal disks, the Purcell effect is dominant for enhanced PL intensity, whereas for small size disks the main contribution comes from plasmon scattering at the disk edge within the light cone collected by the microscope objective.展开更多
We study the two coupling two-level single molecules driven by an external field as a photon pair source. The probability of emitting two photons, P2, is employed to describe the photon pair source quality in a short ...We study the two coupling two-level single molecules driven by an external field as a photon pair source. The probability of emitting two photons, P2, is employed to describe the photon pair source quality in a short time, and the correlation coefficient RAB is employed to describe the photon pair source quality in a long time limit. The results demonstrate that the coupling single quantum emitters can be considered as a stable photon pair source.展开更多
The 1.55-μm quantum-dot (QD) micropillar cavities are strongly required as single photon sources (SPSs) for silica-fiber-based quantum information processing. Theoretical analysis shows that the adiabatic distributed...The 1.55-μm quantum-dot (QD) micropillar cavities are strongly required as single photon sources (SPSs) for silica-fiber-based quantum information processing. Theoretical analysis shows that the adiabatic distributed Bragg reflector (DBR) structure may greatly improve the quality of a micropillar cavity. An InGaAsP/InP micropillar cavity is originally difficult, but it becomes more likely usable with inserted tapered (thickness decreased towards the center) distributed DBRs. Simulation turns out that, incorporating adiabatically tapered DBRs, a Si/SiO2- InP hybrid micropillar cavity, which enables weakly coupling InAs/InP quantum dots (QDs), can even well satisfy strong coupling at a smaller diameter. Certainly, not only the tapered structure, other adiabatic designs, e.g., both DBR layers getting thicker and one thicker one thinner, also improve the quality, reduce the diameter, and degrade the fabrication difficulty of Si/SiO2-InP hybrid micropillar cavities. Furthermore, the problem of the thin epitaxial semiconductor layer can also be greatly resolved by inserting adiabatic InGaAsP/InP DBRs. With tapered DBRs, the InGaAsP/InP-air-aperture micro-pillar cavity serves as an efficient, coherent, and monolithically producible 1.55-μm single-photon source (SPS). The adiabatic design is thus an effective way to obtain prospective candidates for 1.55-μm QD SPSs.展开更多
Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an effic...Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source.By properly modeling the target states,a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique,and hence our method reduces the resource consumption without loss of accuracy.We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data.Explicitly,the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states.Our method could be generalized to estimate other kinds of states,as well as other quantum information tasks.展开更多
Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Io...Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility(BRIF)and the future High Intensity Heavy-ion Accelerator Facility(HIAF),we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system.The overall performance of this state-of-the-art technique was evaluated,and the system was commissioned using a bunched stable ion beam.The high-resolution optical spectra for the 4s ^(2)S_(1/2)→4p^(2)P_(3/2)(D2)ionic transition of ^(40;42;44;48)Ca isotopes were successfully measured.The extracted isotope shifts relative to ^(40)Ca showed excellent agreement with the literature values.This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonance ionization spectroscopy techniques.展开更多
We propose a photon-photon collider based on synchrotron gamma sources driven by relativistic electron beams in hollow plasma channels.The collimated(with a divergence angle of~1 mrad)and ultrabrilliant(>10^(28)pho...We propose a photon-photon collider based on synchrotron gamma sources driven by relativistic electron beams in hollow plasma channels.The collimated(with a divergence angle of~1 mrad)and ultrabrilliant(>10^(28)photons s^(-1)·mrad^(-2)·mm^(-2)per 0.1% bandwidth at 0.6 MeV)photon beams are generated by strong electromagnetic fields induced by current filamentation instability,and up to~10^(6) Breit-Wheeler(BW)pairs can be created per shot.Notably,the usage of hollow plasma channels not only enhances synchrotron radiation,but also allows flexible control of the produced photon beams,ensuring the alignment of the two colliding beams and maximizing the two-photon BW process.This setup has the advantage of a clean background by eliminating the yield from the nonlinear BW process,and the signal-to-noise ratio is higher than 10^(2).展开更多
The pursuit of high-quality single-photon sources has long been hampered by challenges in improving the performance and robustness.While traditional microcavity structures can achieve impressive performance,they suffe...The pursuit of high-quality single-photon sources has long been hampered by challenges in improving the performance and robustness.While traditional microcavity structures can achieve impressive performance,they suffer from extreme sensitivity to manufacturing uncertainty,structural disorders,and scatterings.Topological photonics potentially offers a powerful toolbox for solving these problems.A recent breakthrough by researchers from the Beijing Academy of Quantum Information Sciences,published in Light:Science&Applications,exploits a topological bulk state rather than the already reported edge and corner states to enhance the single photon emission for a quantum dot.展开更多
目的评估双源CT Sn 100kVp能谱纯化用于低剂量肺结节筛查的诊断效能。方法纳入2020年4月至2023年12月期间在南京医科大学附二院接受至少两次低剂量CT检查的100名肺结节患者,将初检患者纳入常规电压组[(以110 kVp、52 mAs行常规电压低剂...目的评估双源CT Sn 100kVp能谱纯化用于低剂量肺结节筛查的诊断效能。方法纳入2020年4月至2023年12月期间在南京医科大学附二院接受至少两次低剂量CT检查的100名肺结节患者,将初检患者纳入常规电压组[(以110 kVp、52 mAs行常规电压低剂量螺旋CT(LDCT)扫描)],复检患者纳入低电压组(以Sn 100kVp、70 mAs行低电压能谱纯化低剂量双源CT扫描),比较两组辐射剂量、客观图像质量评价、主观图像质量评分及诊断效能。结果低电压组的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)和有效辐射剂量(ED)均显著低于常规电压组(P均<0.05)。低电压组肺窗标准差(SD)低于常规电压组,肺窗对比噪声比(CNR)高于常规电压组(P均<0.05)。低电压组肺窗、纵隔窗主观图像质量评分低于常规电压组(P均<0.05)。与病理结果相比,常规电压LDCT检测肺结节的Kappa指数为0.944,双源CT Sn 100kVp检测肺结节的Kappa指数为0.917,均与病理结果一致性良好。结论本研究表明,双源CT Sn 100kVp能谱纯化技术在低剂量肺结节筛查中展现出良好的诊断效能,同时显著降低了辐射剂量,为临床提供了一种更为安全有效的筛查方法。展开更多
In a breakthrough that promises to revolutionize quantum photonic systems,researchers have successfully demonstrated a high-performance,ultracompact polarization-entangled photon-pair source using the van der Waalsbas...In a breakthrough that promises to revolutionize quantum photonic systems,researchers have successfully demonstrated a high-performance,ultracompact polarization-entangled photon-pair source using the van der Waalsbased two-dimensional 3R-wS2 crystal.This achievement opens new avenues for integrated quantum technologies,paving the way for advanced applications in quantum computing,communication,and metrology.展开更多
Beijing,March 27,2025-The Institute of High Energy Physics(IHEP)of the Chinese Academy of Sciences announced today that the High Energy Photon Source(HEPS),a major national science and technology infrastructure projec...Beijing,March 27,2025-The Institute of High Energy Physics(IHEP)of the Chinese Academy of Sciences announced today that the High Energy Photon Source(HEPS),a major national science and technology infrastructure project,has successfully completed its preliminary beam commissioning and officially entered the joint commissioning phase(Figure 1A).With an investment of 4.76 billion RMB(∼$657 million),this“super microscope”is designed to redefine the spatiotemporal resolution limits of matter structure research by delivering X-rays with a brilliance that surpasses that of sunlight by a trillion-fold.展开更多
Purpose The High Energy Photon Source(HEPS)is designed to be one of the world’s brightest synchrotron light sources.In this paper,we provide an overview of the initial commissioning process of the HEPS storage ring,f...Purpose The High Energy Photon Source(HEPS)is designed to be one of the world’s brightest synchrotron light sources.In this paper,we provide an overview of the initial commissioning process of the HEPS storage ring,from the start of commissioning to the achievement of the first beam storage.We introduce the possible challenges that may arise during this critical phase of commissioning and detail the efforts made to achieve this important milestone in the HEPS storage ring commissioning.Methods The commissioning process began with transportation through the high-energy transfer line BR(Booster-to-Ring),followed by beam injection and the first-turn transportation.This was followed by iterative trajectory correction and optimization,primarily utilizing a self-developed trajectory correction program based on the independently developed high-level application framework,Pyapas.Through iterative manual adjustment of the variable parameters,we successfully advanced the beam further.Subsequently,the RF cavities and sextupole magnets were gradually powered on.Through multi-turn trajectory correction and parameters optimization in a larger variable space,beam storage in the HEPS storage ring was achieved.Results On July 23,the first beam injection and the first-turn beam transportation were achieved within a few hours of starting the storage ring commissioning.By July 29,the beam circulation exceeded 10 turns,and by August 4,the beam circulated in the storage ring more than 1000 turns.On August 6,the first beam storage in the HEPS storage ring was achieved.Furthermore,the storage ring beam current reached approximately 60 microamperes on the same day.Conclusion The successful beam storage is a significant milestone in the HEPS storage ring commissioning and a solid step toward the completion of the HEPS construction.It is hoped that the process to reach this achievement,as presented in this paper,will provide a useful reference for the commissioning of similar facilities both domestically and internationally.展开更多
基金supported by the Guangdong Basic and Applied Basic Research Foundation,China(No.2021B1515140007).
文摘The Southern Advanced Photon Source(SAPS)is a diffraction-limited synchrotron light source under design,which employs longitudinal injection as its primary injection scheme.This kind of injection scheme requires that the injected beam has a short bunch length and low emittance,and the preferred injector should offer high stability and low cost.Therefore,an injector based on a booster synchrotron was developed.The proposed injector includes a 250 MeV linac,a booster synchrotron that ramps the beam energy to 3.5 GeV,and two beam transport lines to ensure efficient beam delivery and beam quality preservation.The linac utilizes a thermionic high-voltage DC gun for reliable operation and features a bunching system with an advanced focusing system to preserve the emittance.To meet the injection requirements of the SAPS,a comprehensive design for the booster has been conducted.The booster synchrotron employs a threefold lattice structure,incorporating modified theoretical minimum emittance cells with a small momentum compaction factor and a high voltage to achieve an emittance of 3.98 nm rad and a bunch length of 4.8 mm.The injector has the potential to deliver a high charge,reducing the injection period of the storage ring to less than 1 min.Simulations demonstrated the expected performance,with a transmission efficiency of 90%,confirming its capability to meet the injection requirement of the SAPS storage ring.This design offers a stable and efficient solution for the SAPS.
基金supported by the Quantum Science and Technology-National Science and Technology Major Project (Grant No.2024ZD0302502 for WZ)the National Natural Science Foundation of China(Grant No.92365210 for WZ)+1 种基金Tsinghua Initiative Scientific Research Program (for WZ)the project of Tsinghua University-Zhuhai Huafa Industrial Share Company Joint Institute for Architecture Optoelectronic Technologies (JIAOT,for YH)。
文摘To fully utilize the resources provided by optical fiber networks,a cross-band quantum light source generating photon pairs,where one photon in a pair is at C band and the other is at O band,is proposed in this work.This source is based on spontaneous four-wave mixing(SFWM)in a piece of shallow-ridge silicon waveguide.Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width,enabling broadband photon pair generation by SFWM across C band and O band.The spontaneous Raman scattering(SpRS)in silicon waveguides is also investigated experimentally.It shows that there are two regions in the spectrum of generated photons from SpRS,which could be used to achieve cross-band photon pair generation.A chip of shallow-ridge silicon waveguide samples with different ridge widths has been fabricated,through which cross-band photon pair generation is demonstrated experimentally.The experimental results show that the source can be achieved using dispersion-optimized shallow-ridge silicon waveguides.This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extends applications of quantum networks.
基金supported by the National Key Research and Development Program(No.2022YFE0107400)the internal research funding from Photonic View Technology Technology Co.,Ltd.the GuangCi Deep Mind Project of Ruijin Hospital Shanghai Jiao Tong University School of Medicine.
文摘The single-molecule detection tech-nique plays a pivotal role in elucidat-ing the fundamental mechanisms of various scientific processes at the molecular level,and holds essential im-portance in multiple fields including physics,biology,and chemistry.Re-cently,single-molecule detection has garnered increasing attention owing to its practical utility in medical diagno-sis,primarily due to its exceptional sensitivity and the minimal sample volume required for analysis.However,the conventional single-molecule technique,represented by total internal reflection microscopy,faces challenges such as sophisticated operation procedures and limited detection throughput,thereby impeding its broader application.To address these limitations,we have demonstrated single-molecule detection using an integrated silicon photonic chip,of-fering a cost-effective and user-friendly alternative.By employing basic optics,we efficiently introduce the excitation source for single-molecule fluorescence by harnessing the strong evanescent field of high refractive-index waveguides.Subsequently,fluorescence signals are collected using basic optics comprising a water-immersion objective,relay optics,and a digi-tal camera.Our results highlight a low-cost,high-throughput single-molecule technique achieved through the integrated silicon photonic chip.This innovative approach is promised to facilitate the widespread adoption of single-molecule fluorescence in medical diagnosis.
基金Project supported by the National Key Basic Research Program of China (Grant No 2007CB31040)the National Natural Science Foundation of China (Grant No 60571020)
文摘This paper presents a three-dimensional particle-in-cell （PIC） simulation of a Ka-band relativistic Cherenkov source with a slow wave structure （SWS） consisting of metal photonic band gap （PBG） structures. In the simulation, a perfect match layer boundary is employed to absorb passing band modes supported by the PBG lattice with an artificial metal boundary. The simulated axial field distributions in the cross section and surface of the SWS demonstrate that the device operates in the vicinity of the π point of a TM01-1ike mode. The Fourier transformation spectra of the axial fields as functions of time and space show that only a single frequency appears at 36.27 GHz, which is in good agreement with that of the intersection of the dispersion curve with the slow space charge wave generated on the beam. The simulation results demonstrate that the SWS has good mode selectivity.
基金financially supported by the ERC Starting Grant No.715770(QD-NOMS)the National Natural Science Foundation of China(No.61728501)
文摘Single photon sources are key components for quantum technologies such as quantum communication, computing and metrology. A key challenge towards the realization of global quantum networks are transmission losses in optical fibers. Therefore, single photon sources are required to emit at the low-loss telecom wavelength bands. However, an ideal telecom wavelength single photon source has yet to be discovered. Here, we review the recent progress in realizing such sources. We start with single photon emission based on atomic ensembles and spontaneous parametric down conversion, and then focus on solid-state emitters including semiconductor quantum dots, defects in silicon carbide and carbon nanotubes. In conclusion, some state-of-the-art applications are highlighted.
基金Project supported by the National Natural Science Foundation of China (Grant No 60578055)the State Key Development Program for Basic Research of China (Grant No 2007CB307001)
文摘Recently the performance of the quantum key distribution （QKD） is substantially improved by the decoy state method and the non-orthogonal encoding protocol, separately. In this paper, a practical non-orthogonal decoy state protocol with a heralded single photon source （HSPS） for QKD is presented. The protocol is based on 4 states with different intensities. i.e. one signal state and three decoy states. The signal state is for generating keys; the decoy states are for detecting the eavesdropping and estimating the fraction of single-photon and two-photon pulses. We have discussed three cases of this protocol, i.e. the general case, the optimal case and the special case. Moreover, the final key rate over transmission distance is simulated. For the low dark count of the HSPS and the utilization of the two-photon pulses, our protocol has a higher key rate and a longer transmission distance than any other decoy state protocol.
基金financial support from the National Key R&D Program of China(No.2016YFB0401600)the National Natural Science Foundation of China(No.61635009)the Fundamental Research Funds for the Central Universities(No.2018FZA5004)
文摘Single-photon sources are building blocks for photonic quantum information processes. Of the many single-photon generation schemes, electrically driven single-photon sources have the advantages of realizing monolithic integration of quantum light sources and detectors without optical filtering, thus greatly simplify the integrated quantum photonic circuits. Here, we review recent advances on electrically driven single-photon sources based on solid-state quantum emitters, such as semiconductor epitaxial quantum dots, colloidal quantum dots, carbon nanotubes, molecules, and defect states in diamond, SiC and layered semiconductors. In particular, the merits and drawbacks of each system are discussed. Finally, the article is concluded by discussing the challenges that remain for electrically driven single-photon sources.
基金supported by the National Key Research and Development Program of China(Grant No.2016YFA0302700)the National Natural Science Foundation of China(Grants No.61725504,61327901,61490711,11821404 and11774335)+2 种基金the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(CAS)(Grant No.QYZDY-SSWSLH003)Anhui Initiative in Quantum Information Technologies(AHY060300 and AHY020100)the Fundamental Research Funds for the Central Universities(Grant NosWK2030380017 and WK2470000026)
文摘The intrinsic characteristics of single photons became critical issues since the early development of quantum mechanics. Nowadays, acting as flying qubits, single photons are shown to play important roles in the quantum key distribution and quantum networks. Many different single photon sources (SPSs) have been developed. Point defects in silicon carbide (SiC) have been shown to be promising SPS candidates in the telecom range. In this work, we demonstrate a stable SPS in an epitaxial 3CSiC with the wavelength in the near C-band range, which is very suitable for fiber communications. The observed SPSs show high single photon purity and stable fluorescence at even above 400 K. The lifetimes of the SPSs are found to be almost linearly decreased with the increase of temperature. Since the epitaxial 3C-SiC can be conveniently nanofabricated, these stable near Cband SPSs would find important applications in the integrated photonic devices.
基金Supported by the National Key Basic Research Program of China under Grant No 2013CB922304the National Natural Science Foundation of China under Grant Nos 11474275 and 11464034
文摘We investigate metallic microdisk-size dependence of quantum dot （QD） spontaneous emission rate and micro- antenna directional emission effect for the hybrid metM-distributed Bragg reflector structures based on a particular single QD emission. It is found that the measured photolumineseence （PL） intensity is very sensitive to the size of metMlic disk, showing an enhancement factor of 11 when the optimal disk diameter is 2μm and the numerical aperture of microscope objective NA=0.5. It is found that for large metal disks, the Purcell effect is dominant for enhanced PL intensity, whereas for small size disks the main contribution comes from plasmon scattering at the disk edge within the light cone collected by the microscope objective.
基金Project supported by the National Natural Science Foundation of China(Grand Nos.91021009,21073110,and 11374191)the Natural Science Foundation of Shandong Province,China(Grant No.ZR2013AQ020)+2 种基金the Postdoctoral Science Foundation of China(Grant No.2013M531584)the Doctoral Program of Higher Education of China(Grant Nos.20130131110005 and 20130131120006)the Taishan Scholarship Project of Shandong Province,China
文摘We study the two coupling two-level single molecules driven by an external field as a photon pair source. The probability of emitting two photons, P2, is employed to describe the photon pair source quality in a short time, and the correlation coefficient RAB is employed to describe the photon pair source quality in a long time limit. The results demonstrate that the coupling single quantum emitters can be considered as a stable photon pair source.
基金supported by the Sichuan Science and Technology Program under Grant No.2018JY0084
文摘The 1.55-μm quantum-dot (QD) micropillar cavities are strongly required as single photon sources (SPSs) for silica-fiber-based quantum information processing. Theoretical analysis shows that the adiabatic distributed Bragg reflector (DBR) structure may greatly improve the quality of a micropillar cavity. An InGaAsP/InP micropillar cavity is originally difficult, but it becomes more likely usable with inserted tapered (thickness decreased towards the center) distributed DBRs. Simulation turns out that, incorporating adiabatically tapered DBRs, a Si/SiO2- InP hybrid micropillar cavity, which enables weakly coupling InAs/InP quantum dots (QDs), can even well satisfy strong coupling at a smaller diameter. Certainly, not only the tapered structure, other adiabatic designs, e.g., both DBR layers getting thicker and one thicker one thinner, also improve the quality, reduce the diameter, and degrade the fabrication difficulty of Si/SiO2-InP hybrid micropillar cavities. Furthermore, the problem of the thin epitaxial semiconductor layer can also be greatly resolved by inserting adiabatic InGaAsP/InP DBRs. With tapered DBRs, the InGaAsP/InP-air-aperture micro-pillar cavity serves as an efficient, coherent, and monolithically producible 1.55-μm single-photon source (SPS). The adiabatic design is thus an effective way to obtain prospective candidates for 1.55-μm QD SPSs.
基金Project supported by the National Key Research and Development Program of China (Grant No.2019YFA0705000)Leading-edge technology Program of Jiangsu Natural Science Foundation (Grant No.BK20192001)the National Natural Science Foundation of China (Grant No.11974178)。
文摘Neural networks are becoming ubiquitous in various areas of physics as a successful machine learning(ML)technique for addressing different tasks.Based on ML technique,we propose and experimentally demonstrate an efficient method for state reconstruction of the widely used Sagnac polarization-entangled photon source.By properly modeling the target states,a multi-output fully connected neural network is well trained using only six of the sixteen measurement bases in standard tomography technique,and hence our method reduces the resource consumption without loss of accuracy.We demonstrate the ability of the neural network to predict state parameters with a high precision by using both simulated and experimental data.Explicitly,the mean absolute error for all the parameters is below 0.05 for the simulated data and a mean fidelity of 0.99 is achieved for experimentally generated states.Our method could be generalized to estimate other kinds of states,as well as other quantum information tasks.
基金supported by the National Natural Science Foundation of China(Nos.12027809,U1967201,11875073,11875074 and 11961141003)National Key R&D Program of China(No.2018YFA0404403)+1 种基金China National Nuclear Corporation(No.FA18000201)the State Key Laboratory of Nuclear Physics and Technology,Peking University(No.NPT2019ZZ02).
文摘Collinear laser spectroscopy is a powerful tool for studying the nuclear spins,electromagnetic moments,and charge radii of exotic nuclei.To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion-beam Facility(BRIF)and the future High Intensity Heavy-ion Accelerator Facility(HIAF),we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system.The overall performance of this state-of-the-art technique was evaluated,and the system was commissioned using a bunched stable ion beam.The high-resolution optical spectra for the 4s ^(2)S_(1/2)→4p^(2)P_(3/2)(D2)ionic transition of ^(40;42;44;48)Ca isotopes were successfully measured.The extracted isotope shifts relative to ^(40)Ca showed excellent agreement with the literature values.This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonance ionization spectroscopy techniques.
基金supported by the Fund of the National Key Laboratory of Plasma Physics(Grant No.6142A04230204)the National Natural Science Foundation of China(Project No.12075046).
文摘We propose a photon-photon collider based on synchrotron gamma sources driven by relativistic electron beams in hollow plasma channels.The collimated(with a divergence angle of~1 mrad)and ultrabrilliant(>10^(28)photons s^(-1)·mrad^(-2)·mm^(-2)per 0.1% bandwidth at 0.6 MeV)photon beams are generated by strong electromagnetic fields induced by current filamentation instability,and up to~10^(6) Breit-Wheeler(BW)pairs can be created per shot.Notably,the usage of hollow plasma channels not only enhances synchrotron radiation,but also allows flexible control of the produced photon beams,ensuring the alignment of the two colliding beams and maximizing the two-photon BW process.This setup has the advantage of a clean background by eliminating the yield from the nonlinear BW process,and the signal-to-noise ratio is higher than 10^(2).
基金Open Access funding enabled and organized by Projekt DEAL。
文摘The pursuit of high-quality single-photon sources has long been hampered by challenges in improving the performance and robustness.While traditional microcavity structures can achieve impressive performance,they suffer from extreme sensitivity to manufacturing uncertainty,structural disorders,and scatterings.Topological photonics potentially offers a powerful toolbox for solving these problems.A recent breakthrough by researchers from the Beijing Academy of Quantum Information Sciences,published in Light:Science&Applications,exploits a topological bulk state rather than the already reported edge and corner states to enhance the single photon emission for a quantum dot.
文摘目的评估双源CT Sn 100kVp能谱纯化用于低剂量肺结节筛查的诊断效能。方法纳入2020年4月至2023年12月期间在南京医科大学附二院接受至少两次低剂量CT检查的100名肺结节患者,将初检患者纳入常规电压组[(以110 kVp、52 mAs行常规电压低剂量螺旋CT(LDCT)扫描)],复检患者纳入低电压组(以Sn 100kVp、70 mAs行低电压能谱纯化低剂量双源CT扫描),比较两组辐射剂量、客观图像质量评价、主观图像质量评分及诊断效能。结果低电压组的容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)和有效辐射剂量(ED)均显著低于常规电压组(P均<0.05)。低电压组肺窗标准差(SD)低于常规电压组,肺窗对比噪声比(CNR)高于常规电压组(P均<0.05)。低电压组肺窗、纵隔窗主观图像质量评分低于常规电压组(P均<0.05)。与病理结果相比,常规电压LDCT检测肺结节的Kappa指数为0.944,双源CT Sn 100kVp检测肺结节的Kappa指数为0.917,均与病理结果一致性良好。结论本研究表明,双源CT Sn 100kVp能谱纯化技术在低剂量肺结节筛查中展现出良好的诊断效能,同时显著降低了辐射剂量,为临床提供了一种更为安全有效的筛查方法。
文摘In a breakthrough that promises to revolutionize quantum photonic systems,researchers have successfully demonstrated a high-performance,ultracompact polarization-entangled photon-pair source using the van der Waalsbased two-dimensional 3R-wS2 crystal.This achievement opens new avenues for integrated quantum technologies,paving the way for advanced applications in quantum computing,communication,and metrology.
基金funded by the research project"The Chinese Academy of Sciences Discipline Development History:Case Studies on Major Missions and Discipline Development(E3293Z06)""Foundamental Theoretical Issues in Philosophy of Engineering Science"(23JZD006),Major Projest in the Philosophy and Social Sciences funded by Ministry of Education of China.
文摘Beijing,March 27,2025-The Institute of High Energy Physics(IHEP)of the Chinese Academy of Sciences announced today that the High Energy Photon Source(HEPS),a major national science and technology infrastructure project,has successfully completed its preliminary beam commissioning and officially entered the joint commissioning phase(Figure 1A).With an investment of 4.76 billion RMB(∼$657 million),this“super microscope”is designed to redefine the spatiotemporal resolution limits of matter structure research by delivering X-rays with a brilliance that surpasses that of sunlight by a trillion-fold.
基金supported by the high-energy photon source(HEPS),a major national science and technology infrastructurethe National Natural Science Foundation of China(No.11922512,12375149).
文摘Purpose The High Energy Photon Source(HEPS)is designed to be one of the world’s brightest synchrotron light sources.In this paper,we provide an overview of the initial commissioning process of the HEPS storage ring,from the start of commissioning to the achievement of the first beam storage.We introduce the possible challenges that may arise during this critical phase of commissioning and detail the efforts made to achieve this important milestone in the HEPS storage ring commissioning.Methods The commissioning process began with transportation through the high-energy transfer line BR(Booster-to-Ring),followed by beam injection and the first-turn transportation.This was followed by iterative trajectory correction and optimization,primarily utilizing a self-developed trajectory correction program based on the independently developed high-level application framework,Pyapas.Through iterative manual adjustment of the variable parameters,we successfully advanced the beam further.Subsequently,the RF cavities and sextupole magnets were gradually powered on.Through multi-turn trajectory correction and parameters optimization in a larger variable space,beam storage in the HEPS storage ring was achieved.Results On July 23,the first beam injection and the first-turn beam transportation were achieved within a few hours of starting the storage ring commissioning.By July 29,the beam circulation exceeded 10 turns,and by August 4,the beam circulated in the storage ring more than 1000 turns.On August 6,the first beam storage in the HEPS storage ring was achieved.Furthermore,the storage ring beam current reached approximately 60 microamperes on the same day.Conclusion The successful beam storage is a significant milestone in the HEPS storage ring commissioning and a solid step toward the completion of the HEPS construction.It is hoped that the process to reach this achievement,as presented in this paper,will provide a useful reference for the commissioning of similar facilities both domestically and internationally.
