内镜下切开术治疗原发性克罗恩病肛管直肠狭窄的初步探讨

目的评价内镜下切开术(ES)治疗原发性克罗恩病肛管直肠狭窄的临床疗效。方法回顾性分析2018年9月-2019年12月在该院接受ES治疗的原发性克罗恩病肛管直肠狭窄患者的临床资料。结果13例患者共接受22次ES治疗,人均治疗次数(1.7±0.6)次,狭窄长度0.5~10.0 cm,中位数1.5 cm,狭窄直径0.2~0.8 cm,中位数0.4 cm,即时手术成功率100.0%。随访期内,6例ES前未行近端肠管造口术的患者不需要常规手术干预,7例ES治疗前曾行近端肠管造口术的患者3例已经完成造口还纳手术;所有接受ES治疗的患者未出现并发症。结论ES治疗原发性克罗恩病肛管直肠狭窄安全、有效。

Up-conversion detection of mid-infrared light carrying orbital angular momentum

Frequency up-conversion is an effective method of mid-infrared(MIR) detection by converting long-wavelength photons to the visible domain, where efficient detectors are readily available. Here, we generate MIR light carrying orbital angular momentum(OAM) from a difference frequency generation process and perform up-conversion on it via sum frequency conversion in a bulk quasi-phase-matching crystal. The maximum quantum conversion efficiencies from MIR to visible are 34.0%, 10.4%, and 3.5% for light with topological charges of 0, 1, and 2, respectively, achieved by utilizing an optimized strong pump light. We also verify the OAM conservation with a specially designed interferometer, and the results agree well with the numerical simulations. Our study opens up the possibilities for generating, manipulating, and detecting MIR light that carries OAM, and will have great potential for optical communications and remote sensing in the MIR regime.

Orbital angular momentum photonic quantum interface

Light-carrying orbital angular momentum(OAM)has great potential in enhancing the information channel capacity in both classical and quantum optical communications.Long distance optical communication requires the wavelengths of light are situated in the low-loss communication windows,but most quantum memories currently being developed for use in a quantum repeater work at different wavelengths,so a quantum interface to bridge the wavelength gap is necessary.So far,such an interface for OAM-carried light has not been realized yet.Here,we report the first experimental realization of a quantum interface for a heralded single photon carrying OAM using a nonlinear crystal in an optical cavity.The spatial structures of input and output photons exhibit strong similarity.More importantly,single-photon coherence is preserved during up-conversion as demonstrated.

Spectrally multiplexed and bright entangled photon pairs in a lithium niobate microresonator

On-chip bright quantum sources with multiplexing ability are extremely high in demand for integrated quantum networks with unprecedented scalability and complexity.Here,we demonstrate a bright and broadband biphoton quantum source with spectral multiplexing generated in a lithium niobate microresonator system.Without introducing the conventional domain poling,the on-chip microdisk produces photon pairs covering a broad bandwidth promised by natural phase matching in spontaneous parametric down conversion.Experimentally,the multiplexed photon pairs are characterized by 30 nm bandwidth limited by the filtering system,providing over 40 multiplexing channels with a 0.8 nm channel spacing.Meanwhile,the generation rate reaches 5.13 MHz/μW with a coincidence-to-accidental ratio up to 804,and the quantum source manifests a high purity with a heralded single photon correlation g^((2))_(H)(0)=0.0098±0.0021.Furthermore,the energy-time entanglement is demonstrated with an excellent interference visibility of 96.5%±2%.Such a quantum source at the telecommunication band paves the way for high-dimensional entanglement and future integrated quantum information systems.

Quantum twisted double-slits experiments:confirming wavefunctions'physical reality

Are quantum states real? This most fundamental question in quantum mechanics has not yet been satisfactorily resolved, although its realistic interpretation seems to have been rejected by various delayedchoice experiments. Here, to address this long-standing issue, we present a quantum twisted double-slit experiment. By exploiting the subluminal feature of twisted photons, the real nature of a photon during its time in flight is revealed for the first time. We found that photons' arrival times were inconsistent with the states obtained in measurements but agreed with the states during propagation. Our results demonstrate that wavefunctions describe the realistic existence and evolution of quantum entities rather than a pure mathematical abstraction providing a probability list of measurement outcomes. This finding clarifies the long-held misunderstanding of the role of wavefunctions and their collapse in the evolution of quantum entities.

High-dimensional entanglement between distant atomic-ensemble memories

Entangled quantum states in high-dimensional space show many advantages compared with entangled states in two-dimensional space.The former enable quantum communication with higher channel capacity,enable more efficient quantum-information processing and are more feasible for closing the detection loophole in Bell test experiments.Establishing high-dimensional entangled memories is essential for long-distance communication,but its experimental realization is lacking.We experimentally established high-dimensional entanglement in orbital angular momentum space between two atomic ensembles separated by 1 m.We reconstructed the density matrix for a three-dimensional entanglement and obtained an entanglement fidelity of(83.9±2.9)%.More importantly,we confirmed the successful preparation of a state entangled in more than three-dimensional space(up to seven-dimensional)using entanglement witnesses.Achieving high-dimensional entanglement represents a significant step toward a high-capacity quantum network.

Harmonics-assisted optical phase amplifier

The change in the relative phase between two light fields serves as a basic principle for the measurement of the physical quantity that guides this change.It would therefore be highly advantageous if the relative phase could be amplified to enhance the measurement resolution.One well-known method for phase amplification involves the use of the multi-photon number and path-entangled state known as the NOON state;however,a high-number NOON state is very diffcult to prepare and is highly sensitive to optical losses.Here we propose and experimentally demonstrate in principle a phase amplifer scheme with the assistance of a harmonic generation process.The relative phase difference between two polarization modes in a polarized interferometer is amplified coherently four times with cascaded second-harmonic generation processes.We demonstrate that these amplification processes can be recycled and therefore have the potential to realize much higher numbers of multiple amplification steps.The phase amplification method presented here shows considerable advantages over the method based on NOON states and willbe highly promising for use in precision optical measurements.

Generation of multiphoton quantum states on silicon

Multiphoton quantum states play a critical role in emerging quantum technologies and greatly improve our fundamental understanding of the quantum world.Integrated photonics is well recognized as an attractive technology offering great promise for the generation of photonic quantum states with high-brightness,tunability,stability,and scalability.Herein,we demonstrate the generation of multiphoton quantum states using a single-silicon nanophotonic waveguide.The detected four-photon rate reaches 0.34 Hz even with a low-pump power of 600μW.This multiphoton quantum state is also qualified with multiphoton quantum interference,as well as quantum state tomography.For the generated four-photon states,the quantum interference visibilities are greater than 95%,and the fidelity is 0.78±0.02.Furthermore,such a multiphoton quantum source is fully compatible with the on-chip processes of quantum manipulation,as well as quantum detection,which is helpful for the realization of large-scale quantum photonic integrated circuits(QPICs)and shows great potential for research in the area of multiphoton quantum science.

Quantum interface for high-dimensional quantum states encoded in an orbital angular momentum space

Quantum information science involves the study of information pro-cessing tasks that can be accomplished using quantum mechanical sys-tems.The basic unit of quantum information is a quantum bit(qubit),which exists in a two-dimensional space spanned for example by the or-thogonal polarization states of a photon.In this case,each photon carries only one qubit.However,if the photon is encoded in a high-dimensional space.

Angular-spectrum-dependent interference

Optical interference is not only a fundamental phenomenon that has enabled new theories of light to be derived but it has also been used in interferometry for the measurement of small displacements,refractive index changes,and surface irregularities.In a two-beam interferometer,variations in the interference fringes are used as a diagnostic for anything that causes the optical path difference(OPD)to change;therefore,for a specified OPD,greater variation in the fringes indicates better measurement sensitivity.Here,we introduce and experimentally validate an interesting optical interference phenomenon that uses photons with a structured frequency-angular spectrum,which are generated from a spontaneous parametric down-conversion process in a nonlinear crystal.This interference phenomenon is manifested as interference fringes that vary much more rapidly with increasing OPD than the corresponding fringes for equal-inclination interference;the phenomenon is parameterised using an equivalent wavelength,which under our experimental conditions is 29.38 nm or about 1/27 of the real wavelength.This phenomenon not only enriches the knowledge with regard to optical interference but also offers promise for applications in interferometry.