This paper proposes a candidate framework for free-space quantum key distribution (QKD) based on geometrical-configuration modulation (GM). In the minimal implementation considered here, Alice coherently splits a single photon emitted from one source into two spatial output modes with a tunable separation, and uses the source separation R as the GM variable that defines the prepared single-photon spatial superposition state. Bob records the single-photon detection coordinate in the far field or Fourier plane, providing the correlated data used for soft-input information reconciliation. Based on this physical mechanism, we first establish an R-x protocol model in which the source separation R and the single-photon detection coordinate x are random variables, and further propose an R-Δx extension based on the difference variable Δx between adjacent accepted detection events to mitigate slowly varying center drift in free-space links. The framework specifies state preparation, far-field conditional probabilities, soft-input information generation, parameter estimation, reconciliation, and asymptotic candidate key-rate formulas. A complete composable security analysis further requires derive an explicit computable upper bound on Eve's information from experimentally observed parameters, together with finite-key analysis and experimental validation under free-space conditions. The proposed candidate framework (GM-QKD) provides a modulation approach based on spatial degrees of freedom in which the source geometry serves as the modulation variable.

We propose Geometric-Configuration Modulation (GM), a novel AO-free FSO paradigm utilizing multi-source geometric configuration encoding and active correlative decoding. GM demonstrates exceptional resistance to strong atmospheric turbulence (D/r_0∼ 5) over a 1.2 m link in preliminary experiments.

Random numbers are one of the key foundations of cryptography.This work implements a discrete quan-tum random number generator(QRNG)based on the tunneling effect of electrons in an avalanche photo diode.Without any post-processing and conditioning,this QRNG can output raw sequences at a rate of 100 Mbps.Re-markably,the statistical min-entropy of the 8,000,000 bits sequence reaches 0.9944 bits/bit,and the min-entropy validated by NIST SP 800-90B reaches 0.9872 bits/bit.This metric is currently the highest value we have inves-tigated for QRNG raw sequences.Moreover,this QRNG can continuously and stably output raw sequences with high randomness over extended periods.The system produced a continuous output of 1,174 Gbits raw sequence for a duration of 11,744 s,with every 8 Mbits forming a unit to obtain a statistical min-entropy distribution with an average value of 0.9892 bits/bit.The statistical min-entropy of all data(1,174 Gbits)achieves the value of 0.9951 bits/bit.This QRNG can produce high-quality raw sequences with good randomness and stability.It has the potential to meet the high demand in cryptography for random numbers with high quality.

We propose a novel combination of coherent detection with single-pixel imaging to produce, for the first time, single-pixel full-field simultaneous spatial and velocity imaging. We experimentally demonstrated that both a clear spatial image and a clear velocity map can be created at a low sampling rate using the compressed sensing algorithm. The experimental setup can measure speeds from 2.66 cm/s to 1327.34 cm/s at an resolution of 2.66 cm/s. This dual-modality proposal expands the range of applications for single-pixel imaging.

We propose a new experimentally verified ghost imaging[GI]mechanism,derivative GI.Our innovation is that we use the derivatives of the intensities of the test light and the reference light for imaging.Experimental results show that by com-bining derivative GI with the standard GI algorithm,multiple independent signals can be obtained in one measurement.This combination greatly reduces the number of measurements and the time required for data acquisition and imaging.Derivative GI intrinsically does not produce the storage-consuming background term of GI,so it is suitable for on-chip implementation and makes practical application of GI easier.

Based on traditional ghost imaging (TGI) and differential ghost imaging (DGI), an arbitrary-matrix differential ghost imaging (ADGI) method, which can be adjusted by a self-defined matrix, is proposed. The image of stains on the lens of the reference path is successfully extracted, and it can be used to enhance the image clarity. This method can reduce the influence of occlusion in the reference path and the random interference in the image. We believe that this may provide convenience for the practical application of pseudo thermal ghost imaging.

We propose a concurrent single-pixel imaging, object location, and classification scheme based on deep learning (SP-ILC). We used multitask learning, developed a new loss function, and created a dataset suitable for this project. The dataset consists of scenes that contain different numbers of possibly overlapping objects of various sizes. The results we obtained show that SP-ILC runs concurrent processes to locate objects in a scene with a high degree of precision in order to produce high quality single-pixel images of the objects, and to accurately classify objects, all with a low sampling rate. SP-ILC has potential for effective use in remote sensing, medical diagnosis and treatment, security, and autonomous vehicle control.

通过混凝土经历10～-40、10～-80、10～-160℃等3种典型的超低温温度区间冻融循环作用试验,探讨不同的温度区间和冻融循环作用次数对混凝土峰值应变的影响.结果 表明,经历不同温度区间冻融循环作用混凝土上下限温度时的混凝土峰值应变变化趋势不同.随冻融循环作用次数不断地增加,下限温度较低温度区间的混凝土峰值应变将不再增加而呈减小趋势.但各温度区间混凝土下限温度时的混凝土峰值应变因混凝土内孔隙水结冰均比其上限温度时大;不同温度区间的混凝土相对峰值应变差以及上下限温度时单次冻融软化指标和累积冻融软化指标均存在明显的差异且变化规律较为复杂.由试验结果拟合出混凝土相对峰值应变与超低温冻融循环作用的温度区间和次数间的关系式.所获得的这些结果可为LNG储罐类混凝土结构的设计和安全性能评估提供参考.

Ghost imaging (GI) is an imaging technique that uses the second-order correlation between two light beams to obtain the image of an object. However, standard GI is affected by optical background noise, which reduces its practical use. We investigated the robustness of an instant ghost imaging (IGI) algorithm against optical background noise and compare it with the conventional GI algorithm. Our results show that IGI is extremely resistant to spatiotemporally varying optical background noise that can change over a large range. When the noise is large in relation to the signal, IGI will still perform well in conditions that prevent the conventional GI algorithm from generating an image because IGI uses signal differences for imaging. Signal differences are intrinsically resistant to common noise modes, so the IGI algorithm is strongly robust against noise. This research is of great significance for the practical application of GI.

Ghost imaging (GI) is an imaging technique that uses the correlation between two light beams to reconstruct the image of an object. Conventional GI algorithms require large memory space to store the measured data and perform complicated offline calculations, limiting practical applications of GI. Here we develop an instant ghost imaging (IGI) technique with a differential algorithm and an implemented high-speed on-chip IGI hardware system. This algorithm uses the signal between consecutive temporal measurements to reduce the memory requirements without degradation of image quality compared with conventional GI algorithms. The on-chip IGI system can immediately reconstruct the image once the measurement finishes; there is no need to rely on post-processing or offline reconstruction. This system can be developed into a realtime imaging system. These features make IGI a faster, cheaper, and more compact alternative to a conventional GI system and make it viable for practical applications of GI.

Single-pixel imaging (SPI) uses a single-pixel detector to create an image of an object. SPI relies on a computer to construct an image, thus increasing both the size and cost of SPI and limiting its application. We developed instant single-pixel imaging (ISPI), an on-chip SPI system that implements real-time imaging at a rate of 25 fps. ISPI uses the instant ghost imaging algorithm we proposed which leverages signal differences for image creation. It does not require a computer, which greatly reduces its cost and size. The reconstruct time of ISPI for image creation is almost zero because little processing is required after signal detection. ISPI paves the way for the practical application of SPI.

Previously, we built up a set of photon-free quantum random number generator(QRNG) with InGaAs single photon avalanche diodes. We exploited the stochastic property of quantum tunneling effect. Here, we utilized tunneling signals in Si diodes to implement quantum random number generator. In our experiment, instead of applying periodic pulses between the diode as we did in the InGaAs QRNG, we applied fixed voltage and detect time intervals between adjacent tunneling signals, as random source. This Si QRNG has a high performance in the randomness of its raw data and almost post-processing-free. Final data rate in our experiment is 6.98MB/s and could reach 23MB/s if the temperature-control system is ameliorated.

Through the experiments of the concrete with different water contents subjected to cryogenic freeze -thaw cycles from room temperature to -190 ℃, the effect of concrete water content on the deformation behavior of the concrete was discussed.From the test results,it could be shown that the relative elastic module and the relative peak strain at lower and upper limit temperatures for the concrete after cryogenic freeze-thaw cycles were increased and decreased respectively with the increase of concrete water content.Further, the increment of the relative elastic module at lower limit temperature was relatively larger than that at upper limit temperature,while the variation range of the relative peak strain was small so that the effect of concrete-water content on the concrete peak strain could be ignored.At the same time,the relative elastic module and the relative peak strain of the concrete at lower and upper limit temperatures for the concrete with different water contents after cryogenic freeze -thaw action were decreased and increased respectively with the increase of freeze-thaw cycles.And the relative elastic module of the concrete with higher concrete water content was more likely to be affected,while the concrete water content had little effect on the relative peak strain.

In this paper, a realistic interpretation(REIN) of the wave function in quantum mechanics is briefly presented. We demonstrate that in the REIN, the wave function of a microscopic object is its real existence rather than a mere mathematical description.Specifically, the quantum object can exist in disjointed regions of space just as the wave function is distributed, travels at a finite speed, and collapses instantly upon a measurement. Furthermore, we analyze the single-photon interference in a Mach-Zehnder interferometer(MZI) using the REIN. Based on this, we propose and experimentally implement a generalized delayed-choice experiment, called the encounter-delayed-choice experiment, where the second beam splitter is decided whether or not to insert at the encounter of two sub-waves along the arms of the MZI. In such an experiment, the parts of the sub-waves, which do not travel through the beam splitter, show a particle nature, whereas the remaining parts interfere and thus show a wave nature. The predicted phenomenon is clearly demonstrated in the experiment, thus supporting the REIN idea.

通过不同形状和尺寸的混凝土试件经历常温降至-196℃再回温的作用,探讨混凝土内温度在降温和回温过程中的变化规律以及降温回温作用速率、试件的形状和尺寸等对其的影响.结果表明,混凝土内温度在降温回温过程中呈现出显著的滞后性且降温与回温过程存在较大的差异,反映出混凝土在超低温环境下仍具有明显的热惰性,但与高温时不尽相同.混凝土内温度的变化以及与作用温度间的温差受降温回温作用速率和试件尺寸的影响明显且呈现非线性关系.在常温至-196℃温度作用范围最小边长不小于100 mm试件的内外最大温差可达100℃,并且在降温过程中混凝土内温度低于反转温度时,其温度变化速率将达到甚至超过降温作用速率,但混凝土内各处温度变化的回温速率始终低于作用速率.这些试验结果可为(LNG)储罐类混凝土结构设计提供参考.

There have been a large number of strengthening methods for existing building structures,but it is necessary to select a proper method from them and in some cases even the improve them or to give a new strengthening method based on analyzing the damage characteristics of the building structures that need to be strengthened.Through an actual concrete frame-shear wall structure renovation project,the structural damage situation,the reason of damage and the influence of the damage on the structural mechanical properties are examined and analyzed.Then an appropriate strengthening method is given according to the combined above-mentioned examining and analyzing results.The strengthening approaches given in this paper can serve as a reference to better strengthen similar existing buildings structures.

通过混凝土经历两种超低温冻融循环作用工况的试验,探究混凝土超低温冻融循环作用下的受压变形性能.结果表明,随冻融循环作用次数的增加,超低温冻融循环作用上限温度时,因冻融损伤的累积效应使混凝土的弹性模量和峰值应变分别呈下降和增大的变化趋势;而超低温冻融循环作用下限温度时,因混凝土孔隙水结冰作用明显、产生的影响对冲了冻融损伤的累积效应使混凝土的弹性模量保持不变或略有增长、峰值应变变小.超低温冻融循环作用导致的混凝土弹性模量损失与其降温引起的峰值应变增长量有良好的对应关系,而超低温冻融循环的上限温度是否回到常温对混凝土受压变形性能的影响则不大.这些可为可靠地设计LNG类储罐预应力混凝土结构提供依据.

On the basis of the experiments of cryogenic freeze-thaw cydes from room temperature to -190 ℃ on the concrete with different water contents,the effect of the concrete water content on the mechanical properties of the concrete was discussed.Test results show that the mechanical properties of theconcrete with different water contents were obviously different.After the the cryogenic freeze-thaw cycles,the concrete compressive strength,both at lower and upper limits of the freeze-thaw temperature,was significantly improved with the increase of the concrete water content.While the concrete compressive strength at the upper limit temperature was always decreased with the increase of the freeze-thaw cycles,totally different from that at the lower limit temperature,which was closely related to the concrete water content.The relative compressive strength increment of the concrete at cryogenic temperature after freeze-thaw cydes depends more than before on the water content.Based on the experiment results and the existing investigations results,a fitting formula of the relative compressive strength increment for the concrete experiencing the action of different cryogenic freeze-thaw cycles was given,which can be used in the design of concrete structures at the cryogenic temperature such as the LNG tanks.