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Semi-quantum key distribution describes a system in which a fully quantum user and classical user perform key distribution. The main advantage of key distribution is its security. Owing to the bottlenecks of existing technology, highly attenuated lasers and threshold detectors are required for semi-quantum key distribution; however, these components make semi-quantum key distribution susceptible to eavesdroppers. Our previous study presented the first semi-quantum key distribution experiment and verified the feasibility of the mirror protocol in 2021. Herein, we first build a semi-quantum key distribution channel model and use Gottesman-Lo-Lütkenhaus-Preskill theory to evaluate its safety performance in the case of a quasi-single photon source. Moreover, we determine that an eavesdropper can steal all information through the photon-number-splitting attack without being detected. Therefore, we add decoy states to the semi-quantum key distribution to estimate the furthest transmission distance and secure bit rate under asymptotic conditions. Semi-quantum key distribution can still be achieved safely with highly attenuated lasers and threshold detectors in 150 km.

The visible light communication (VLC) system employs large viewing divergence angle light-emitting diode (LED) to realize illumination and communication simultaneously, so the geometric loss of optical power may reach tens of decibels, moreover, considering the gain reduction of the LED at high frequency, signal power at the receiver will be too weak. To overcome these drawbacks, in this paper, a low output impedance power driver amplifier is presented to provide enough power to drive a medium power commercial LED used at the end of the optical transmitter. A 125 Mbit/s real-time communication with illumination and communication angle of 130° has been achieved at a distance of 3 m, the bit error rate (BER) is 3.13×10−11 at a divergence angle of LED of 0° and 1.21×10−6 at a communication angle of 130°. Experimental results indicated that this VLC system can be used for illumination and communication simultaneously.

Ni-based catalysts are the most promising catalysts for CO2 methanation. The development of catalysts with low-temperature activity could bring significant energy and environmental benefits. In this work, the hydrogenation of CO2 to methane was studied on Ni-M/γ-Al2O3 (M = Fe, Co, or Mn) bimetallic catalysts. The optimum reaction was obtained using Ni-Mn/γ-Al2O3 (CO2 conversion: 85%, CH4 selectivity: 99%, 280 °C). In situ FTIR studies revealed the excellent performance of Ni-Mn/γ-Al2O3, which lowers the required reaction temperature. Based on in situ FTIR studies, CO2 methanation proceeded over three intermediates on the catalysts: bicarbonate → carbonate → formate → methane. The second metal (Co or Mn) promoted the dispersion of both Ni and itself and improved the ability of Ni to crack H2. And introduced more oxygen vacancies to strengthen the basicity of surrounding O2− on the surface of the catalysts. In effect, the number of carbonate active sites could be increased accordingly, thereby improving the adsorption capacity for CO2.

Influences of 170-keV protons beam irradiation on the static and dynamic properties of blue light InGaN/GaN multiple quantum wells (MQWs) microlight-emitting diodes (Micro-LEDs) were investigated. It was interesting to find out that, although threshold voltage and light output power of Micro-LEDs deteriorated after proton irradiation, a 3-dB bandwidth was greatly improved. In quantitative terms, at the forward current density of 1 kA/cm2, 3-dB bandwidth increased from original 7.34 to 119.74 MHz when Micro-LED exposed to proton beam with the fluence of $5\times 10^{14}$ p/cm2. Based on the frequency response data analysis, differential carrier lifetimes of Micro-LEDs, including Shockley–Read–Hall (SRH) lifetime and differential radiation recombination lifetime, were compared. The results pointed out that both SRH and recombination lifetimes became shorter after proton irradiation, indicating that competition between the nonradiative and radiative recombination processes was enhanced by proton beam. To reveal the origination of the 3-dB bandwidth improvement, photoluminescence (PL) and time-resolved PL (TRPL) spectrums of Micro-LEDs were measured. MQWs’ PL spectrum with a peak wavelength of 450 nm was observed and its intensity decreased as proton fluence increasing. Meanwhile, a PL peak at 550 nm, which was well known as defect-related PL spectrum, was enhanced by proton irradiation, especially at a proton fluence of $5\times 10^{13}$ and $5\times 10^{14}$ p/cm2, proving the increase of defects in epitaxial thin films as proton fluence increasing. In the TRPL experimental study, the nonradiative recombination lifetime decreased with proton fluence, which was consistent with the results analyzed by frequency response. Overall, the improvement of 3-dB bandwidth could be mainly attributed to the decrease of carrier lifetime in MQWs, which were caused by the generation of defects due to the atom displacement effect of proton irradiation.

Semi-quantum key distribution (SQKD) is used to establish a string of shared secret keys between a quantum party and a classical party. Here, we report the first proof-of-principle experimental demonstration of SQKD based on the Mirror protocol, which is the most experimentally feasible SQKD protocol, and equipped with time-phase encoding scheme employing the method of selective modulation. The experiment was performed at a repetition frequency of 62.5 MHz and a high raw key rate arrived at 69.8 kbps, and the average quantum bit error rate was found to be 4.56% and 2.78% for the “SWAP-x-Z” ($\mathrm{x}\in \{01,10\}$ x ∈ { 01 , 10 } ) and the “CTRL-X”, respectively. The results demonstrate the feasibility of our system, and this study is helpful for future research on SQKD experiments.

An efficient phase stabilization method is required in quantum key distribution (QKD) systems for stability in practical applications. The existing active phase compensation method has limitations in multi-node network applications, especially in network-scale applications based on measurement-device-independent QKD systems. In this study, we propose a local active phase compensation scheme that can realize phase compensation independently for each interferometer node. We performed experimental demonstrations in the BB84 phase encoding system based on a Faraday–Michelson interferometer. The average QBER rates of the system under two different forms of the reference light were found to be 1.9% and 1.6%. This scheme can also be applied to other QKD systems and has potential for application in future quantum communication networks.

Phase drifting is an intrinsic problem in the various phase-encoding quantum key distribution (QKD) system. This letter presents a novel local active phase compensation (LAPC) method, in which the phase drift of the interferometer for each node is tracked and compensated separately. The proof-of-principle demonstration is implemented based on the two common BB84 prepare-and-measure QKD systems, and the experiment result shows that our LAPC setup can run steadily for above 10 hours. A test quantum key distribution based on the Mach–Zehnder interferometer QKD system and the Faraday–Michelson interferometer QKD system with an average quantum bit error rate of 3.8% and 1.9% was achieved, respectively. This study demonstrates the validity of the LAPC method for the BB84 phase-encoding prepare-and-measure QKD system, and then the potential for its use in large-scale QKD networks, while offering a simpler scheme for the practical operation of the MDI-QKD system and the star-type MDI QKD network.

In this paper, a splitting ratio-adjustable Mach-Zehnder interferometer (MZI) for the measurement of relative humidity (RH) is proposed and experimentally demonstrated. The sensing head contains three sections of single mode fiber (SMF) and two sections of multimode fiber (MMF), in which the two MMFs are spliced among the three SMFs. The MMFs are corroded with hydrofluoric acid and act as mode couplers to split and recombine light owing to the core diameter mismatch with the SMF. A layer of graphene oxide (GO) is coated on the MMFs by dip-coating and natural evaporation. The effective refractive index of the GO will vary when it absorbs the water molecules. As a result, the intensity of the transmission light in the core and cladding of the single mode fiber can be adjusted. Thus, the intensity of the resonant dip will vary when the relative humidity changes. The experimental results show that a humidity sensitivity of 0.263 dB/RH% with a linear correlation coefficient of 99% can be achieved in a relative humidity range of 35% to 85%.

A driveline model with 6° of freedom is established, the detailed structure of a clutch with three stages nonlinear stiffness and damping is presented and modeled, and the model for a driveline with unloaded gears and the nonlinear clutch is proposed. Taking the angular acceleration amplitude of the input shaft for a transmission as an evaluation index, the influence of model parameters on the angular acceleration of the input shaft is studied. For reducing gear rattle of the unloaded meshed gears of a generic passenger car, the proposed clutch is prototyped and its torsional stiffness, damping and moment of inertia of clutch driven disc are optimized to reduce the rattle. Experiment validates the performances of the developed clutch and the proposed clutch model.

The experimental demonstration of measurement-device-independent quantum key distribution (MDI-QKD) has been widely demonstrated. Thus far, several experimental groups have implemented polarization encoding MDI-QKD but with manual polarization controllers, or polarization modulators that make circular polarization states unstable. Here, we apply an intrinsically stable polarization-modulated unit (PMU) to MDI-QKD so that Alice and Bob can modulate four BB84 polarization states, all of which can be kept stable from even the harsh environment. Moreover, our PMU can provide two operational polarization encoding modes suitable to different application scenarios. A proof-of-principle demonstration of MDI-QKD based on our PMU is implemented with an interference visibility of 46.6%, an average quantum bit error rate of 1.49% for the Z basis and the secure key rate of 4.25 × 10−6 bits per pulse. The proposed study is helpful for building polarization encoding MDI-QKD systems with better stability.

Background There are few reports on hemiparesis caused by vascular medullary compression, which can occur because of dolichoectasia of the vertebrobasilar arterial system. In this article, we report a case of vertebral artery compression of the medulla oblongata in a 67-year-old woman. Case Description The patient was hypertensive, and she developed hemiparesis and intermittent spasms over 5 years. These spasms had worsened during the last year. Cranial nerve magnetic resonance imaging showed compression of the medulla oblongata by the left vertebral artery. A motor evoked potential (MEP) examination showed abnormal conduction of MEPs of bilateral toe abductors. The patient underwent microvascular decompression surgery under general anesthesia through a retrosigmoid keyhole approach. This operation led to relief of vascular compression and symptomatic improvement. Conclusions Our case suggests that detailed history, imaging studies, and electrophysiologic studies help lead to a correct and early diagnosis of hemiparesis caused by vascular compression of the rostral ventrolateral medulla. Microvascular decompression surgery improves patient symptoms, and intraoperative electrophysiologic monitoring helps to avoid injury to important adjacent nerves.

Hongtao Sun,1,* Maohua Zheng,2,* Yanmin Wang,1 Yunfeng Diao,1 Wanyong Zhao,1 Zhengjun Wei1 1Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People’s Armed Police Force, Tianjin, 2Department of Neurosurgery, The First Hospital of Lanzhou University, Lanzhou, People’sRepublic of China *These authors contributed equally tothis work Objective: The aim of this study was to investigate the clinical significance and changes of brain tissue partial pressure of oxygen (PbtO2) in the course of mild hypothermia treatment (MHT) for treating severe traumatic brain injury (sTBI). Methods: There were 68 cases with sTBI undergoing MHT. PbtO2, intracranial pressure (ICP), jugular venous oxygen saturation (SjvO2), and cerebral perfusion pressure (CPP) were continuously monitored, and clinical outcomes were evaluated using the Glasgow OutcomeScale score. Results: Of 68 patients with sTBI, PbtO2, SjvO2, and CPP were obviously increased, but decreased ICP level was observed throughout the MHT. PbtO2 and ICP were negatively linearly correlated, while there was a positive linear correlation between PbtO2 and SjvO2. Monitoring CPP and SjvO2 was performed under normal circumstances, and a large proportion of patients were detected with low PbtO2. Decreased PbtO2 was also found after MHT. Conclusion: Continuous PbtO2 monitoring could be introduced to evaluate the condition of regional cerebral oxygen metabolism, thereby guiding the clinical treatment and predicting the outcome. Keywords: severe traumatic brain injury, hypothermia, brain tissue partial pressure of oxygen, therapy

Hong-tao Sun,1,* Maohua Zheng,2,* Yanmin Wang,1 Yunfeng Diao,1 Wanyong Zhao,1 Zhengjun Wei1 1Sixth Department of Neurosurgery, Affiliated Hospital of Logistics University of People’s Armed Police Force, Tianjin, 2Department of Neurosurgery, The First Hospital of Lanzhou University, Lanzhou, People’s Republic of China *These authors contributed equally tothis work Abstract: The aim of the study was to evaluate the clinical value of multiple brain parameters on monitoring intracranial pressure (ICP) procedures in the therapy of severe traumatic brain injury (sTBI) utilizing mild hypothermia treatment (MHT) alone or a combination strategy with other therapeutic techniques. A total of 62 patients with sTBI (Glasgow Coma Scale score

A proof-of-principle demonstration of a one-way polarization encoding quantum key distribution (QKD) system is demonstrated. This approach can automatically compensate for birefringence and phase drift. This is achieved by constructing intrinsically stable polarization-modulated units (PMUs) to perform the encoding and decoding, which can be used with four-state protocol, six-state protocol, and the measurement-device-independent (MDI) scheme. A polarization extinction ratio of about 30 dB was maintained for several hours over a 50 km optical fiber without any adjustments to our setup, which evidences its potential for use in practical applications.

The S parameter expression of high-frequency models of the high electron mobility transistors (HEMTs) with basic feedback structure, especially the transmission gain S21, is presented and analyzed. In addition, an improved feedback structure and its theory are proposed and demonstrated, in order to obtain a better gain-flatness through the mutual interaction between the series inductor and the parallel capacitor in the feedback loop. The optimization solution for the feedback amplifier can eliminate the negative impacts on transmission gain S21 caused by things such as resonance peaks. Furthermore, our theory covers the shortage of conventional feedback amplifiers, to some extent. A wideband low-noise amplifier (LNA) with the improved feedback technology is designed based on HEMT. The transmission gain is about 20 dB with the gain variation of 1.2 dB from 100 MHz to 6 GHz. The noise figure is lower than 2.8 dB in the whole band and the amplifier is unconditionally stable.

A passive quench circuit is used to study the punch-through characters of avalanche photodiodes under the Geiger mode. The photocurrent–voltage curve indicated clearly the punch-through voltage while the dark current–voltage curve is insensitive to the punch-through. The experiments demonstrate different distributions of the carries. The dark carriers counts increase much faster than the photo-carriers counts due to the different collection efficiency. A proper selection of the bias can increase the signal-to-noise ratio (SNR) of the single photon detector.

It has been shown that the single photon detectors (SPDs) based on the avalanche photodiode (APD) can be blinded and controlled by the bright light and short trigger pulses. Eavesdropper can get the full information without causing additional quantum bit error rate. Hence, in order to guarantee the security of the quantum key distribution (QKD) systems, some countermeasures, by changing the characteristic of the SPD or monitoring the parameters of the detector, are presented by some research groups. In this paper, we provide a new and effective countermeasure against the blinding attack based on improving the optical scheme of the decoding unit in the QKD system rather than only considering the characteristic of the SPD. In our proposal we use a coupler with asymmetric splitting ratio to distinguish the detection characteristic of the SPD with blinding attack from that without blinding attack. The detailed analysis shows that the proposed scheme is feasible to defense the blinding attack.

Phase drift is an inherent problem in one-way phase-encoded quantum key distribution (QKD) systems. Although combining passive with active phase compensation (APC) processes can effectively compensate for the phase drift, the security problems brought about by these processes are rarely considered. In this paper, we point out a security hole in the APC process and put forward a corresponding attack scheme. Under our proposed attack, the quantum bit error rate (QBER) of the QKD can be close to zero for some conditions. However, under the same conditions the ratio r of the key “0” and the key “1” which Bob (the legal communicators Alice and Bob) gets is no longer 1:1 but 2:1, which may expose Eve (the eavesdropper). In order to solve this problem, we modify the resend strategy of the attack scheme, which can force r to reach 1 and the QBER to be lower than the tolerable QBER.

Differential phase shift quantum key distribution scheme has been improved by introducing a passive path selection structure at the transmitter including two polarization controllers used to mark the photon pulses and a polarizing beam splitter to distinguish these pulses so that can make different time delay at the receiver. Theoretical analysis indicates that a free-space-based differential phase shift quantum key distribution system with this proposed improvement will have high efficiency with the utilization ratio of photons reaching 100% under ideal condition.

Objective China is experiencing a rapid increase in cancer incidence in elderly patients. In order to better understand this group, a large study of patients from multiple tertiary centers in the Beijing area was designed. This study was designed to provide insight into their unique treatment preferences, including the use of traditional Chinese medicine (TCM). Materials and Methods 803 patients from nine hospitals in the Beijing area were enrolled into this study. The inclusion criteria were patients who were 65 years or older and had a diagnosis of cancer at any stage. The CGA questionnaire used with these patients included the Chinese translation of the Gero-Oncology Health and Quality of Life Assessment tool. The questionnaire was provided to patients by a research nurse and was administered in Mandarin. Results The mean age of the patients was 72 years (range 65–94). The patients were mainly male (59.8%) and of Han ethnicity (95.4%). About 45% of these patients also had concurrent TCM in addition to their other cancer treatments. About 70% were able to manage their activities of daily living without assistance. Patients on TCM were more likely to have higher number of co-morbidities compared to their counterparts. Conclusion This is the largest prospective study of CGA assessments done on elderly patients with cancer in Asia. The study demonstrates that CGA provides insights into understanding the needs of elderly Chinese patients with cancer. TCM is used frequently in China, and its impact on quality of life needs further investigation.

Background Hemimasticatory spasm is a rare clinical entity characterized by involuntary and paroxysmal contractions of the jaw-closing muscles on 1 side of the face. Although its cause is not fully known, vascular compression of the trigeminal nerve has been speculated. Case Description Here, we report 1 case of hemimasticatory spasm that was cured by microvascular decompression of the motor branch of the trigeminal nerve; a relevant literature review was also performed. Conclusions Hemimasticatory spasm is a rare disease that may be recalcitrant to conservative medical therapy, and vascular decompression of the trigeminal nerve may be required to relieve the spasm.

A new method to detect infrared single photon using avalanche photodiodes is proposed, which combine the requirements of a single photon detector control circuit and features of the electric pulses generator by transient process of transmission lines. When the terminated boundary conditions of transmission lines are changed quickly, voltage across the switch devices will drop suddenly in the electric pulses generator model and at the same time a signal that can reflect the drive information of the switch device will export from load resistance. So we can replace the switch with avalanche photodiodes who can act as an excellent optoelectronic switch. Then when faint laser pulses enter the avalanche photodiode, resistance of the avalanche photodiode will decrease quickly and with that voltage across avalanche photodiodes will drop simultaneously and a signal that can reflect the single-photon laser pulses will export from the load resistance. The simulation results are given for the new quenching circuit model of avalanche photodiodes and the analyses emphasis on the feasibility of the quenching model and the influence of each electrical component on the performance of the quenching circuit. Finally optimal parameter of the electrical components in the model is demonstrated.

This paper introduces the design of a single photon detector based on the AT89C51 single chip microcontroller for quantum key distribution at telecommunication wavelengths. An avalanche photodiode (APD) is operated in Geiger mode and stabilized at temperature of 228K for translating the single photon signals into electrical pulses. The photon induced avalanche pulses are amplified and converted to digital data. The microcontroller discriminates the data, counting the number of photons, and then displays the photon number and the detection efficiency on a LCD display. The instrument can effectively support the study of quantum key distribution.

Photon cannot keep itself unchanged from emission to absorption. The information encoded on the photon is also changed due to interaction with environment. There has no definitely demonstration that the photon being absorbed is the original one from ideal light source since the quantum mechanics itself is an indeterminate theory that the physical measurement is only the probability. We divide the change of the photon state into two parts that one can be compensated and the other cannot be compensated. A concept of photon reconstruction is introduced to explain every optical phenomena including Raman scattering, multi-photon absorption, nonlinear phenomena, free electron lasing, quantum entanglement, high order coherence, ghost imaging and the de-phase which result in error bits or information loss in the quantum information process. An experimental result is explained to show that the signal photon can modify the background even the energy of the photon is not enough for absorption in the wide-band gap semiconductor material. The photon-current-voltage curve and dark-current-voltage curve of an absorption, grating, and multiplication InGaAs/InP avalanche photodiode is analyzed to show that 1550nm input light modified the dark background even the applied reverse bias voltage is far below the punch-through voltage. This increase of the dark count directly relates to the input photons at the 1550nm wavelength but is not due to absorption in the absorption layer and insensitive to the applied voltage.

In the quantum key distribution system, quantum channel is always affected by spontaneous Raman scattering noise when it transmits with classical channels that act as synchronization and data channels on a shared fiber. To study the effect of the noise exactly, the temporal distribution characteristics of the Raman scattering noise are analyzed theoretically and measured by a single-photon detector. On the basis of this, a scheme to decrease the noise is proposed.

We propose a scheme for quantum key distribution, in which single photons are encoded with polarization states and then divided and delayed to encode phase differences between two sequential pulses. In an example, the BB84 and DPS (differential phase shift) protocols are combined to achieve single-photon two-qubit quantum key distribution. This scheme can increase the key generation efficiency up to 7/6, higher than that of the conventional single-photon one-qubit quantum key distribution scheme.