Quantum integrability provides a unique and powerful framework for accurately understanding quantum magnetism.In this review,we focus specifically on several quantum integrable low-dimensional quantum Ising models.We ...Quantum integrability provides a unique and powerful framework for accurately understanding quantum magnetism.In this review,we focus specifically on several quantum integrable low-dimensional quantum Ising models.We begin with the transverse field Ising chain(TFIC)at quantum critical point and examine how it evolves under perturbations,such as an applied longitudinal field or weak coupling to another quantum critical TFIC.展开更多
An unconventional integer quantum Hall regime was found in magnetic semiconductor-superconductor hybrids. By making use of the decomposition of the gauge potential on a U（1） principal fibre bundle over k-space, we s...An unconventional integer quantum Hall regime was found in magnetic semiconductor-superconductor hybrids. By making use of the decomposition of the gauge potential on a U（1） principal fibre bundle over k-space, we study the topological structure of the integral Hall conductance. It is labeled by the Hopf index β and the Brouwer degree η. The Hall conductance topological current and its evolution is discussed.展开更多
We investigate the integrability of the Rabi model,which is traditionally viewed as not Yang–Baxter-integrable despite its solvability.Building on efforts by Bogoliubov and Kulish(2013 J.Math.Sci.19214–30),Amico et ...We investigate the integrability of the Rabi model,which is traditionally viewed as not Yang–Baxter-integrable despite its solvability.Building on efforts by Bogoliubov and Kulish(2013 J.Math.Sci.19214–30),Amico et al(2007 Nucl.Phys.B 787283–300),and Batchelor and Zhou(2015 Phys.Rev.A 91053808),who explored special limiting cases of the model,we develop a spin–boson interaction Hamiltonian under more general boundary conditions,particularly focusing on open boundary conditions with off-diagonal terms.Our approach maintains the direction of the spin in the z direction and also preserves the boson particle number operator a^(†)a,marking a progression beyond previous efforts that have primarily explored reduced forms of the Rabi model from Yang–Baxter algebra.We also address the presence of‘unwanted’quadratic boson terms a^(2) and a^(†2),which share coefficients with the boson particle number operator.Interestingly,these terms vanish when spectral parameter u=±θ_(s),simplifying the model to a limiting case of operator-valued twists,a scenario previously discussed by Batchelor and Zhou(2015 Phys.Rev.A 91053808).展开更多
Quantum communications aim to share encryption keys between the transmitters and receivers governed by the laws of quantum mechanics.Integrated quantum photonics offers significant advantages of dense integration,high...Quantum communications aim to share encryption keys between the transmitters and receivers governed by the laws of quantum mechanics.Integrated quantum photonics offers significant advantages of dense integration,high stability and scalability,which enables a vital platform for the implementation of quantum information processing and quantum communications.This article reviews recent experimental progress and advances in the development of integrated quantum photonic devices and systems for quantum communications and quantum networks.展开更多
We construct an integrable 1D extended Hubbard model within the framework of the quantum inverse scattering method.With the help of the nested algebraic Bethe ansatz method,the eigenvalue Hamiltonian problem is solved...We construct an integrable 1D extended Hubbard model within the framework of the quantum inverse scattering method.With the help of the nested algebraic Bethe ansatz method,the eigenvalue Hamiltonian problem is solved by a set of Bethe ansatz equations,whose solutions are supposed to give the correct energy spectrum.展开更多
For the requirement of quantum photonic integration in on-chip quantum information,we propose a scheme to realize quantum controlled-Z(CZ)gates through single gradient metasurface.Using its parallel beam-splitting fea...For the requirement of quantum photonic integration in on-chip quantum information,we propose a scheme to realize quantum controlled-Z(CZ)gates through single gradient metasurface.Using its parallel beam-splitting feature,i.e.,a series of connected beamsplitters with the same splitting ratio,one metasurface can support a polarization encoding CZ gate or path encoding CZ gate,several independent CZ gates,and cascade CZ gates.Taking advantage that the path of output state is locked by the polarization of input state,path encoding CZ gates can efficiently filter out bit-flip errors coming from beam-splitting processes.These CZ gates also have the potential to detect quantum errors and generate high-dimensional entanglement through multi-degree-of-freedom correlation on metasurfaces.By integrating quantum CZ gates into a single metasurface,our results open an avenue for high-density and multifunctional integration of quantum devices.展开更多
The integration of sensing and communication can achieve ubiquitous sensing while enabling ubiquitous communication.Within the gradually improving global communication,the integrated sensing and communication system b...The integration of sensing and communication can achieve ubiquitous sensing while enabling ubiquitous communication.Within the gradually improving global communication,the integrated sensing and communication system based on optical fibers can accomplish various functionalities,such as urban structure imaging,seismic wave detection,and pipeline safety monitoring.With the development of quantum communication,quantum networks based on optical fiber are gradually being established.In this paper,we propose an integrated sensing and quantum network(ISAQN)scheme,which can achieve secure key distribution among multiple nodes and distributed sensing under the standard quantum limit.The continuous variables quantum key distribution protocol and the round-trip multiband structure are adopted to achieve the multinode secure key distribution.Meanwhile,the spectrum phase monitoring protocol is proposed to realize distributed sensing.It determines which node is vibrating by monitoring the frequency spectrum and restores the vibration waveform by monitoring the phase change.The scheme is experimentally demonstrated by simulating the vibration in a star structure network.Experimental results indicate that this multiuser quantum network can achieve a secret key rate of approximately 0.7 Mbits/s for each user under 10-km standard fiber transmission,and its network capacity is 8.In terms of distributed sensing,it can achieve a vibration response bandwidth ranging from 1 Hz to 2 kHz,a strain resolution of 0.50 nε/Hz,and a spatial resolution of 0.20 m under shot-noise-limited detection.The proposed ISAQN scheme enables simultaneous quantum communication and distributed sensing in a multipoint network,laying a foundation for future large-scale quantum networks and high-precision sensing networks.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
Using an exact Bethe ansatz solution,we rigorously study excitation spectra of the spin-1/2 Fermi gas(called Yang–Gaudin model)with an attractive interaction.Elementary excitations of this model involve particle-hole...Using an exact Bethe ansatz solution,we rigorously study excitation spectra of the spin-1/2 Fermi gas(called Yang–Gaudin model)with an attractive interaction.Elementary excitations of this model involve particle-hole excitation,hole excitation and adding particles in the Fermi seas of pairs and unpaired fermions.The gapped magnon excitations in the spin sector show a ferromagnetic coupling to the Fermi sea of the single fermions.By numerically and analytically solving the Bethe ansatz equations and the thermodynamic Bethe ansatz equations of this model,we obtain excitation energies for various polarizations in the phase of the Fulde–Ferrell–Larkin–Ovchinnikov-like state.For a small momentum(long-wavelength limit)and in the strong interaction regime,we analytically obtained their linear dispersions with curvature corrections,effective masses as well as velocities in particle-hole excitations of pairs and unpaired fermions.Such a type of particle-hole excitations display a novel separation of collective motions of bosonic modes within paired and unpaired fermions.Finally,we also discuss magnon excitations in the spin sector and the application of Bragg spectroscopy for testing such separated charge excitation modes of pairs and single fermions.展开更多
Themass production and the practical number of cryogenic quantum devices producible in a single chip are limited to the number of electrical contact pads and wiring of the cryostat or dilution refrigerator.It is,there...Themass production and the practical number of cryogenic quantum devices producible in a single chip are limited to the number of electrical contact pads and wiring of the cryostat or dilution refrigerator.It is,therefore,beneficial to contrast themeasurements of hundreds of devices fabricated in a single chip in one cooldown process to promote the scalability,integrability,reliability,and reproducibility of quantum devices and to save evaluation time,cost and energy.Here,we used a cryogenic on-chip multiplexer architecture and investigated the statistics of the 0.7 anomaly observed on the first three plateaus of the quantized conductance of semiconductor quantum point contact(QPC)transistors.Our single chips contain 256 split gate field-effect QPC transistors(QFET)each,with two 16-branch multiplexed source-drain and gate pads,allowing individual transistors to be selected,addressed and controlled through an electrostatic gate voltage process.A total of 1280 quantum transistors with nano-scale dimensions are patterned in 5 different chips of GaAs heterostructures.From the measurements of 571 functioning QFETs taken at temperatures T[1.4 K and T[40 mK,it is found that the spontaneous polarisation model and Kondo effect do not fit our results.Furthermore,some of the features in our data largely agreed with van Hove model with short-range interactions.Our approach provides further insight into the quantum mechanical properties and microscopic origin of the 0.7 anomaly in QFETs,paving the way for the development of semiconducting quantum circuits and integrated cryogenic electronics,for scalable quantum logic control,readout,synthesis,and processing applications.展开更多
The integrated quantum interferometer has provided a promising route for manipulating and measuring quantum states of light with high precision,requiring negligible optical loss,broad bandwidth,robust fabrication tole...The integrated quantum interferometer has provided a promising route for manipulating and measuring quantum states of light with high precision,requiring negligible optical loss,broad bandwidth,robust fabrication tolerance,and scalability.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
Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming,high-speed optical communication,and integrat...Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming,high-speed optical communication,and integrated quantum photonics.It is very challenging to achieve large delay ranges,small footprints,and broad bandwidths simultaneously due to the strong trade-off between the propagation loss and the group refractive index of optical waveguides.In this paper,we propose and experimentally demonstrate multimode-enabled silicon photonic delay line for the first time,which breaks the delay-density limit of singlemode waveguide spirals,towards a broadband,mm^(2)-scale,and ultra-large time delay.By demonstrating low-loss-propagation possibilities for different polarizations and modes,we introduce a novel multimode delay unit by integrating the mode(de)multiplexers and the ultralowloss multimode waveguide spiral supporting the TE_(0),TE_(1),and TE_(2)modes propagating in parallel.The measured propagation losses for the TE_(0),TE_(1),and TE_(2)modes are 0.2 dB/cm,0.31 dB/cm,and 0.49 dB/cm,respectively.In this way,the highest line delay-density of 376.9 ps/cm and low delay loss of 0.004 dB/ps are achieved.Furthermore,we implement a 7-bit tunable multimode photonic delay line and experimentally demonstrate an ultra-large delay range of 12.7 ns with a delay resolution of 100 ps and within an ultra-compact footprint of 3.85mm^(2),enabling a delay density over 3299 ps/mm^(2),showing the largest delay range and the highest delay density among on-chip delay lines reported to date,to the best of our knowledge.展开更多
To date,most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits(PICs)through single-mode optical fibers.This approach p...To date,most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits(PICs)through single-mode optical fibers.This approach presents significant challenges due to the detection complexity,as cryogenic conditions hinder the development of scalable systems.In addition,going towards fully-integrated devices or,at least,removing the optical fibers would be also advantageous to develop compact and cost-efficient solutions featuring a high number of optical modes.This work reports on the direct coupling of a PIC,fabricated by femtosecond laser writing(FLW),and a silicon single-photon avalanche diode(SPAD)array,fabricated in a custom planar technology and compatible with the operation at room temperature.The effectiveness of this solution is shown by achieving perfect coupling and a system detection efficiency as high as 41.0%at a wavelength of 561 nm,which is the highest value reported to date among both heterogeneous/hybrid integrated and directly coupled systems.We also show the robustness of the coupling to misalignments,demonstrating that costly alignment procedures are not needed.Finally,we exploit the SPAD array to characterize a reconfigurable Mach-Zehnder interferometer,i.e.,the basic building block of multimode reconfigurable PICs.This solution provides a new avenue to the design and implementation of quantum photonics experiments,especially effective when compact and cost-efficient systems are needed.展开更多
The importance of integrated quantum photonics in the telecom band is based on the possibility of interfacing with the optical network infrastructure that was developed for classical communications.In this framework,f...The importance of integrated quantum photonics in the telecom band is based on the possibility of interfacing with the optical network infrastructure that was developed for classical communications.In this framework,femtosecond laser-written integrated photonic circuits,which have already been assessed for use in quantum information experiments in the 800-nm wavelength range,have great potential.In fact,these circuits,being written in glass,can be perfectly mode-matched at telecom wavelength to the in/out coupling fibers,which is a key requirement for a low-loss processing node in future quantum optical networks.In addition,for several applications,quantum photonic devices must be dynamically reconfigurable.Here,we experimentally demonstrate the high performance of femtosecond laser-written photonic circuits for use in quantum experiments in the telecom band,and we demonstrate the use of thermal shifters,which were also fabricated using the same femtosecond laser,to accurately tune such circuits.State-of-the-art manipulation of single-and two-photon states is demonstrated,with fringe visibilities greater than 95%.The results of this work open the way to the realization of reconfigurable quantum photonic circuits based on this technological platform.展开更多
Multipartite entangled states like the W-class are of growing interest since they exhibit a variety of possible applications ranging from quantum computation to genuine random number generation. Here, we present a uni...Multipartite entangled states like the W-class are of growing interest since they exhibit a variety of possible applications ranging from quantum computation to genuine random number generation. Here, we present a universal setup to generate high-order single photon W-states based on three-dimensional integrated-photonic waveguide struc- tures. Additionally, we present a novel method to charac- terize the device＇s unitary by means of classical light only.展开更多
Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent pr...Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot （QD） lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of self- organized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength （〉 1.3 μm） QD lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.展开更多
We report an index-coupled distributed feedback quantum cascade laser by employing an equivalent phase shift(EPS) of quarter-wave integrated with a distributed Bragg reflector(DBR) at λ~5.03 μm. The EPS is fabricate...We report an index-coupled distributed feedback quantum cascade laser by employing an equivalent phase shift(EPS) of quarter-wave integrated with a distributed Bragg reflector(DBR) at λ~5.03 μm. The EPS is fabricated through extending one sampling period by 50% in the center of a sampled Bragg grating. The key EPS and DBR pattern are fabricated by conventional holographic exposure combined with the optical photolithography technology, which leads to improved flexibility, repeatability, and cost-effectiveness. Stable single-mode emission can be obtained by changing the injection current or heat sink temperature even under the condition of large driving pulse width.展开更多
We study the approximation of the integration of multivariate functions in the quantum model of computation. Using a new reduction approach we obtain a lower bound of the n-th minimal query error on anisotropic Sobole...We study the approximation of the integration of multivariate functions in the quantum model of computation. Using a new reduction approach we obtain a lower bound of the n-th minimal query error on anisotropic Sobolev class R（Wpr（[0, 1]d）） （r R＋d）. Then combining this result with our previous one we determine the optimal bound of n-th minimal query error for anisotropic Hblder- Nikolskii class R（H∞r（[0,1]d）） and Sobolev class R（W∞r（[0,1]d））. The results show that for these two types of classes the quantum algorithms give significant speed up over classical deterministic and randomized algorithms.展开更多
In this paper we will show how the Bohr–Sommerfeld levels of a quantum completely integrable system can be computed modulo O(h^(∞))by an inductive procedure starting at stage zero with the Bohr–Sommerfeld levels of...In this paper we will show how the Bohr–Sommerfeld levels of a quantum completely integrable system can be computed modulo O(h^(∞))by an inductive procedure starting at stage zero with the Bohr–Sommerfeld levels of the corresponding classical completely integrable system.展开更多
基金supported by the National Natural Science Foundation of China Grant Nos.12450004,12274288the Innovation Program for Quantum Science and Technology Grant No.2021ZD0301900。
文摘Quantum integrability provides a unique and powerful framework for accurately understanding quantum magnetism.In this review,we focus specifically on several quantum integrable low-dimensional quantum Ising models.We begin with the transverse field Ising chain(TFIC)at quantum critical point and examine how it evolves under perturbations,such as an applied longitudinal field or weak coupling to another quantum critical TFIC.
基金Project supported by the National Natural Science Foundation of China (Grant No 10275030)
文摘An unconventional integer quantum Hall regime was found in magnetic semiconductor-superconductor hybrids. By making use of the decomposition of the gauge potential on a U（1） principal fibre bundle over k-space, we study the topological structure of the integral Hall conductance. It is labeled by the Hopf index β and the Brouwer degree η. The Hall conductance topological current and its evolution is discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.12275214,12247103,12047502)the Natural Science Basic Research Program of Shaanxi Province Grant Nos.2021JCW-19 and 2019JQ-107Shaanxi Key Laboratory for Theoretical Physics Frontiers in China.
文摘We investigate the integrability of the Rabi model,which is traditionally viewed as not Yang–Baxter-integrable despite its solvability.Building on efforts by Bogoliubov and Kulish(2013 J.Math.Sci.19214–30),Amico et al(2007 Nucl.Phys.B 787283–300),and Batchelor and Zhou(2015 Phys.Rev.A 91053808),who explored special limiting cases of the model,we develop a spin–boson interaction Hamiltonian under more general boundary conditions,particularly focusing on open boundary conditions with off-diagonal terms.Our approach maintains the direction of the spin in the z direction and also preserves the boson particle number operator a^(†)a,marking a progression beyond previous efforts that have primarily explored reduced forms of the Rabi model from Yang–Baxter algebra.We also address the presence of‘unwanted’quadratic boson terms a^(2) and a^(†2),which share coefficients with the boson particle number operator.Interestingly,these terms vanish when spectral parameter u=±θ_(s),simplifying the model to a limiting case of operator-valued twists,a scenario previously discussed by Batchelor and Zhou(2015 Phys.Rev.A 91053808).
基金support from the Natural Science Foundation of China(61975001)National Key R&D Program of China(2018YFB1107205)+1 种基金Beijing Natural Science Foundation(Z190005)the Key R&D Program of Guangdong Province(2018B030329001).
文摘Quantum communications aim to share encryption keys between the transmitters and receivers governed by the laws of quantum mechanics.Integrated quantum photonics offers significant advantages of dense integration,high stability and scalability,which enables a vital platform for the implementation of quantum information processing and quantum communications.This article reviews recent experimental progress and advances in the development of integrated quantum photonic devices and systems for quantum communications and quantum networks.
基金Financial support from the National Natural Science Foundation of China(Grant Nos.12105221,12175180,12074410,12047502,11934015,11975183,11947301,11775177,11775178 and 11774397)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)+4 种基金the Shaanxi Fundamental Science Research Project for Mathematics and Physics(Grant No.22JSZ005)the Major Basic Research Program of Natural Science of Shaanxi Province(Grant Nos.2021JCW-19,2017KCT-12 and 2017ZDJC-32)the Scientific Research Program Funded by the Shaanxi Provincial Education Department(Grant No.21JK0946)the Beijing National Laboratory for Condensed Matter Physics(Grant No.202162100001)the Double First-Class University Construction Project of Northwest University is gratefully acknowledged.
文摘We construct an integrable 1D extended Hubbard model within the framework of the quantum inverse scattering method.With the help of the nested algebraic Bethe ansatz method,the eigenvalue Hamiltonian problem is solved by a set of Bethe ansatz equations,whose solutions are supposed to give the correct energy spectrum.
基金supported by the National Natural Science Foundation of China under Grants No.12474370,No.12161141010 and No.T2325022by the Innovation Program for Quantum Science and Technology under Grant No.2021ZD0301500.
文摘For the requirement of quantum photonic integration in on-chip quantum information,we propose a scheme to realize quantum controlled-Z(CZ)gates through single gradient metasurface.Using its parallel beam-splitting feature,i.e.,a series of connected beamsplitters with the same splitting ratio,one metasurface can support a polarization encoding CZ gate or path encoding CZ gate,several independent CZ gates,and cascade CZ gates.Taking advantage that the path of output state is locked by the polarization of input state,path encoding CZ gates can efficiently filter out bit-flip errors coming from beam-splitting processes.These CZ gates also have the potential to detect quantum errors and generate high-dimensional entanglement through multi-degree-of-freedom correlation on metasurfaces.By integrating quantum CZ gates into a single metasurface,our results open an avenue for high-density and multifunctional integration of quantum devices.
基金supported by Innovation Program for Quantum Science and Technology(Grant No.2021ZD0300703)the National Natural Science Foundation of China(Grant No.62101320)+1 种基金the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)the Hebei Provincial Science and Technology Project(Grant No.22310701D).
文摘The integration of sensing and communication can achieve ubiquitous sensing while enabling ubiquitous communication.Within the gradually improving global communication,the integrated sensing and communication system based on optical fibers can accomplish various functionalities,such as urban structure imaging,seismic wave detection,and pipeline safety monitoring.With the development of quantum communication,quantum networks based on optical fiber are gradually being established.In this paper,we propose an integrated sensing and quantum network(ISAQN)scheme,which can achieve secure key distribution among multiple nodes and distributed sensing under the standard quantum limit.The continuous variables quantum key distribution protocol and the round-trip multiband structure are adopted to achieve the multinode secure key distribution.Meanwhile,the spectrum phase monitoring protocol is proposed to realize distributed sensing.It determines which node is vibrating by monitoring the frequency spectrum and restores the vibration waveform by monitoring the phase change.The scheme is experimentally demonstrated by simulating the vibration in a star structure network.Experimental results indicate that this multiuser quantum network can achieve a secret key rate of approximately 0.7 Mbits/s for each user under 10-km standard fiber transmission,and its network capacity is 8.In terms of distributed sensing,it can achieve a vibration response bandwidth ranging from 1 Hz to 2 kHz,a strain resolution of 0.50 nε/Hz,and a spatial resolution of 0.20 m under shot-noise-limited detection.The proposed ISAQN scheme enables simultaneous quantum communication and distributed sensing in a multipoint network,laying a foundation for future large-scale quantum networks and high-precision sensing networks.
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supported by the NSFC key grant No.12134015,the NSFC grant No.11874393 and No.12121004
文摘Using an exact Bethe ansatz solution,we rigorously study excitation spectra of the spin-1/2 Fermi gas(called Yang–Gaudin model)with an attractive interaction.Elementary excitations of this model involve particle-hole excitation,hole excitation and adding particles in the Fermi seas of pairs and unpaired fermions.The gapped magnon excitations in the spin sector show a ferromagnetic coupling to the Fermi sea of the single fermions.By numerically and analytically solving the Bethe ansatz equations and the thermodynamic Bethe ansatz equations of this model,we obtain excitation energies for various polarizations in the phase of the Fulde–Ferrell–Larkin–Ovchinnikov-like state.For a small momentum(long-wavelength limit)and in the strong interaction regime,we analytically obtained their linear dispersions with curvature corrections,effective masses as well as velocities in particle-hole excitations of pairs and unpaired fermions.Such a type of particle-hole excitations display a novel separation of collective motions of bosonic modes within paired and unpaired fermions.Finally,we also discuss magnon excitations in the spin sector and the application of Bragg spectroscopy for testing such separated charge excitation modes of pairs and single fermions.
基金financial support from EPSRC,UK.the China Scholarship Council(CSC)for its financial support.
文摘Themass production and the practical number of cryogenic quantum devices producible in a single chip are limited to the number of electrical contact pads and wiring of the cryostat or dilution refrigerator.It is,therefore,beneficial to contrast themeasurements of hundreds of devices fabricated in a single chip in one cooldown process to promote the scalability,integrability,reliability,and reproducibility of quantum devices and to save evaluation time,cost and energy.Here,we used a cryogenic on-chip multiplexer architecture and investigated the statistics of the 0.7 anomaly observed on the first three plateaus of the quantized conductance of semiconductor quantum point contact(QPC)transistors.Our single chips contain 256 split gate field-effect QPC transistors(QFET)each,with two 16-branch multiplexed source-drain and gate pads,allowing individual transistors to be selected,addressed and controlled through an electrostatic gate voltage process.A total of 1280 quantum transistors with nano-scale dimensions are patterned in 5 different chips of GaAs heterostructures.From the measurements of 571 functioning QFETs taken at temperatures T[1.4 K and T[40 mK,it is found that the spontaneous polarisation model and Kondo effect do not fit our results.Furthermore,some of the features in our data largely agreed with van Hove model with short-range interactions.Our approach provides further insight into the quantum mechanical properties and microscopic origin of the 0.7 anomaly in QFETs,paving the way for the development of semiconducting quantum circuits and integrated cryogenic electronics,for scalable quantum logic control,readout,synthesis,and processing applications.
基金National Research Foundation of Korea(2023M3K5A1094805, RS-2024-00343768)National Research Council of Science and Technology (CAP21034-000)+1 种基金Institute for Information and Communications Technology Promotion (2020-0-00972, RS-2024-00396999,RS-2023-00222863)Korea Institute of Science and Technology (KIST) research program (2E33541, 2E33571)
文摘The integrated quantum interferometer has provided a promising route for manipulating and measuring quantum states of light with high precision,requiring negligible optical loss,broad bandwidth,robust fabrication tolerance,and scalability.
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 National Natural Science Foundation of China(U23B2047,62321166651,62305294,62175214,and 92150302)Natural Science Foundation of Zhejiang Province(LD19F050001)+2 种基金Zhejiang Provincial Major Research and Development Program(2022C01103)Fundamental Research Funds for the Central Universities(226202400171)Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(2021R01001).
文摘Integrated optical delay lines have become imperative to meet the growing demand as large aperture antennas and high number of subarrays required for microwave beamforming,high-speed optical communication,and integrated quantum photonics.It is very challenging to achieve large delay ranges,small footprints,and broad bandwidths simultaneously due to the strong trade-off between the propagation loss and the group refractive index of optical waveguides.In this paper,we propose and experimentally demonstrate multimode-enabled silicon photonic delay line for the first time,which breaks the delay-density limit of singlemode waveguide spirals,towards a broadband,mm^(2)-scale,and ultra-large time delay.By demonstrating low-loss-propagation possibilities for different polarizations and modes,we introduce a novel multimode delay unit by integrating the mode(de)multiplexers and the ultralowloss multimode waveguide spiral supporting the TE_(0),TE_(1),and TE_(2)modes propagating in parallel.The measured propagation losses for the TE_(0),TE_(1),and TE_(2)modes are 0.2 dB/cm,0.31 dB/cm,and 0.49 dB/cm,respectively.In this way,the highest line delay-density of 376.9 ps/cm and low delay loss of 0.004 dB/ps are achieved.Furthermore,we implement a 7-bit tunable multimode photonic delay line and experimentally demonstrate an ultra-large delay range of 12.7 ns with a delay resolution of 100 ps and within an ultra-compact footprint of 3.85mm^(2),enabling a delay density over 3299 ps/mm^(2),showing the largest delay range and the highest delay density among on-chip delay lines reported to date,to the best of our knowledge.
文摘To date,most integrated quantum photonics experiments rely on single-photon detectors operating at cryogenic temperatures coupled to photonic integrated circuits(PICs)through single-mode optical fibers.This approach presents significant challenges due to the detection complexity,as cryogenic conditions hinder the development of scalable systems.In addition,going towards fully-integrated devices or,at least,removing the optical fibers would be also advantageous to develop compact and cost-efficient solutions featuring a high number of optical modes.This work reports on the direct coupling of a PIC,fabricated by femtosecond laser writing(FLW),and a silicon single-photon avalanche diode(SPAD)array,fabricated in a custom planar technology and compatible with the operation at room temperature.The effectiveness of this solution is shown by achieving perfect coupling and a system detection efficiency as high as 41.0%at a wavelength of 561 nm,which is the highest value reported to date among both heterogeneous/hybrid integrated and directly coupled systems.We also show the robustness of the coupling to misalignments,demonstrating that costly alignment procedures are not needed.Finally,we exploit the SPAD array to characterize a reconfigurable Mach-Zehnder interferometer,i.e.,the basic building block of multimode reconfigurable PICs.This solution provides a new avenue to the design and implementation of quantum photonics experiments,especially effective when compact and cost-efficient systems are needed.
基金This work was supported by the ERC-Starting Grant 3D-QUEST(3DQuantum Integrated Optical Simulationgrant agreement no.307783,http://www.3dquest.eu)by the Marie Curie Initial Training Network PICQUE(Photonic Integrated Compound Quantum Encoding,grant agreement no.608062,funding Program:FP7-PEOPLE-2013-ITN,http://www.picque.eu).
文摘The importance of integrated quantum photonics in the telecom band is based on the possibility of interfacing with the optical network infrastructure that was developed for classical communications.In this framework,femtosecond laser-written integrated photonic circuits,which have already been assessed for use in quantum information experiments in the 800-nm wavelength range,have great potential.In fact,these circuits,being written in glass,can be perfectly mode-matched at telecom wavelength to the in/out coupling fibers,which is a key requirement for a low-loss processing node in future quantum optical networks.In addition,for several applications,quantum photonic devices must be dynamically reconfigurable.Here,we experimentally demonstrate the high performance of femtosecond laser-written photonic circuits for use in quantum experiments in the telecom band,and we demonstrate the use of thermal shifters,which were also fabricated using the same femtosecond laser,to accurately tune such circuits.State-of-the-art manipulation of single-and two-photon states is demonstrated,with fringe visibilities greater than 95%.The results of this work open the way to the realization of reconfigurable quantum photonic circuits based on this technological platform.
基金financial support from the German Ministry of Education and Research (Center for Innovation Competence program, Grant No. 03Z1HN31)the Thuringian Ministry for Education, Science and Culture (Research group Spacetime, Grant No. 11027-514)+1 种基金the Deutsche Forschungsgemeinschaft (Grant No. NO462/6-1)the German-Israeli Foundation for Scientific Research and Development (Grant No. 1157-127.14/ 2011)
文摘Multipartite entangled states like the W-class are of growing interest since they exhibit a variety of possible applications ranging from quantum computation to genuine random number generation. Here, we present a universal setup to generate high-order single photon W-states based on three-dimensional integrated-photonic waveguide struc- tures. Additionally, we present a novel method to charac- terize the device＇s unitary by means of classical light only.
基金the Defense Advanced Research Projects Agency of the United States under Grant No.W911NF-04-1-0429
文摘Chip-scale integration of optoelectronic devices such as lasers, waveguides, and modulators on silicon is prevailing as a promising approach to realize future ultrahigh speed optical interconnects. We review recent progress of the direct epitaxy and fabrication of quantum dot （QD） lasers and integrated guided-wave devices on silicon. This approach involves the development of molecular beam epitaxial growth of self- organized QD lasers directly on silicon substrates and their monolithic integration with amorphous silicon waveguides and quantum well electroabsorption modulators. Additionally, we report a preliminary study of long-wavelength （〉 1.3 μm） QD lasers grown on silicon and integrated crystalline silicon waveguides using membrane transfer technology.
基金National Basic Research Program of China(2013CB632800)National Key Research and Development Program(2016YFB0402303)+2 种基金National Natural Science Foundation of China(NSFC)(61404131,61435014,61674144,61574136,61627822)Chinese Academy of Sciences Key Project(CAS Key Project)(QYZDJ-SSWJSC027,ZDRW-XH-2016-4)Natural Science Foundation of Beijing Municipality(4162060,4172060)
文摘We report an index-coupled distributed feedback quantum cascade laser by employing an equivalent phase shift(EPS) of quarter-wave integrated with a distributed Bragg reflector(DBR) at λ~5.03 μm. The EPS is fabricated through extending one sampling period by 50% in the center of a sampled Bragg grating. The key EPS and DBR pattern are fabricated by conventional holographic exposure combined with the optical photolithography technology, which leads to improved flexibility, repeatability, and cost-effectiveness. Stable single-mode emission can be obtained by changing the injection current or heat sink temperature even under the condition of large driving pulse width.
基金Supported by National Natural Science Foundation of China (Grant Nos. 10501026 and 60675010)
文摘We study the approximation of the integration of multivariate functions in the quantum model of computation. Using a new reduction approach we obtain a lower bound of the n-th minimal query error on anisotropic Sobolev class R（Wpr（[0, 1]d）） （r R＋d）. Then combining this result with our previous one we determine the optimal bound of n-th minimal query error for anisotropic Hblder- Nikolskii class R（H∞r（[0,1]d）） and Sobolev class R（W∞r（[0,1]d））. The results show that for these two types of classes the quantum algorithms give significant speed up over classical deterministic and randomized algorithms.
基金Supported by the National Key R and D Program of China(Grant No.2020YFA0713100)NSFC(Grant Nos.12026409,11721101,11926313)。
文摘In this paper we will show how the Bohr–Sommerfeld levels of a quantum completely integrable system can be computed modulo O(h^(∞))by an inductive procedure starting at stage zero with the Bohr–Sommerfeld levels of the corresponding classical completely integrable system.
