共线和非共线模式下单光子探测器定标比对实验研究

采用相关光子法定标单光子探测器的量子效率对提高光学载荷的辐射定标准确度具有重要意义.利用355nm连续激光泵浦BBO晶体产生Ⅰ类自发参量下转换,在共线和非共线两种相位匹配模式下分别测量了单光子探测器雪崩光电二极管在736nm波段的量子效率.结果表明,共线和非共线两种模式测量结果的合成不确定度分别为0.71%和0.39%,相对偏差均优于0.4%,这两种模式都可以定标探测器量子效率,且具有很好的一致性.最后比较了两种模式定标探测器量子效率的优缺点,该研究为以后利用相关光子法对遥感器进行辐射定标提供了晶体相位匹配模式选择的依据.     

单光子探测器量子效率绝对自身标定方案

参考已有的方案,提出了一种更简单的方案来实现单光子探测器量子效率的绝对自身标定。我们利用同轴线缆和数据采集卡代替已有方案中的符合测量电路和计数器,通过精确设定同轴线缆的长度,利用电脉冲在同轴线缆的短路终端反射回波的特性,对一个测量周期中单个脉冲和连续两个脉冲进行区分,用数据采集卡记录区分结果,分别得到探测器探测到两个孪生光子的计数和仅探测到其中任意一个光子的计数,从而算出单光子探测器的量子效率。此方案不需要其他任何的参考标准或者另一个探测器.     

Heralded linear optical quantum Fredkin gate based on one auxiliary qubit and one single photon detector

Linear optical quantum Fredkin gate can be applied to quantum computing and quantum multi-user communication networks. In the existing linear optical scheme, two single photon detectors （SPDs） are used to herald the success of the quantum Fredkin gate while they have no photon count. But analysis results show that for non-perfect SPD, the lower the detector efficiency, the higher the heralded success rate by this scheme is. We propose an improved linear optical quantum Fredkin gate by designing a new heralding scheme with an auxiliary qubit and only one SPD, in which the higher the detection efficiency of the heralding detector, the higher the success rate of the gate is. The new heralding scheme can also work efficiently under a non-ideal single photon source. Based on this quantum Fredkin gate, large-scale quantum switching networks can be built. As an example, a quantum Bene~ network is shown in which only one SPD is used.     

单光子探测器量子效率的绝对自身标定方法

提出一种单光子探测器量子效率的绝对自身标定方案，利用光参量下转换过程中产生的光子对在时间上的相关性，先将参量光束分为两路，然后引入相对延时，使同时产生的孪生光子先后进入单光子探测器，然后将探测器之后的电路分为三路，其中一路直接进入计数器得到探测器所探测到的光子的总计数率，另两路用电路方法引入和光路相当的相对延时，经符合电路后进入计数器，得到前后到达探测器的光子对之间的符合计数率.这样，从符合计数率与总光子计数率之比即可在不需要任何其他探测器或者参照标准的情况下获得探测器的量子效率.文中给出两种方案，分别适     

How good must single photon sources and detectors be for efficient linear optical quantum computation?

We present a scheme for linear optical quantum computation that is highly robust to imperfect single photon sources and inefficient detectors. In particular we show that if the product of the detector efficiency with the source efficiency is greater than 2/3, then efficient linear optical quantum computation is possible. This high threshold is achieved within the cluster state paradigm for quantum computation.     

Measurement-device-independent quantum key distribution

How to remove detector side channel attacks has been a notoriously hard problem in quantum cryptography. Here, we propose a simple solution to this problem--measurement-device-independent quantum key distribution (QKD). It not only removes all detector side channels, but also doubles the secure distance with conventional lasers. Our proposal can be implemented with standard optical components with low detection efficiency and highly lossy channels. In contrast to the previous solution of full device independent QKD, the realization of our idea does not require detectors of near unity detection efficiency in combination with a qubit amplifier (based on teleportation) or a quantum nondemolition measurement of the number of photons in a pulse. Furthermore, its key generation rate is many orders of magnitude higher than that based on full device independent QKD. The results show that long-distance quantum cryptography over say 200 km will remain secure even with seriously flawed detectors.     

Tripartite single-photon entangled states in noisy quantum channels

A tripartite single-photon state shared through noisy quantum channels is considered for three different system configurations. The quantum teleportation of a single-photon state between two parties is investigated in cases with and without the assistance of a third party. The condition that the quantum teleportation is superior to the classical one is provided in terms of the damping rate and detector efficiency.     

1.55 μm升频单光子探测量子密钥分配系统的性能研究

分析了1.55 μm升频单光子探测量子密钥分配(QKD)系统的性能,讨论了升频单光子探测器的主要参数：量子效率和暗计数与抽运功率的关系.比较了BB84协议、BBM92协议和DPSK协议的光纤QKD系统的性能：安全通信速率与距离的关系,通过比较得出升频探测器优于传统的InGaAs/InP雪崩二极管单光子探测器,用升频探测器后的通信距离能比传统的大两倍以上,能很好改善量子通信系统的性能. 关键词： 量子效率 通信速率 暗计数     

Quantum efficiency measurements by bidirectional coincidence counting of correlated photon pairs

We propose and demonstrate a procedure for characterizing the quantum efficiency of a single-photon detector in the telecommunication wavelength band. Our procedure employs a bidirectional coincidence counting technique to distinguish optical component losses from the detection efficiency. The standard deviations of the measured quantum efficiencies were nearly identical to the standard deviations derived from a detection probability having a Poisson distribution.     

Experimental study of the efficiency of a SDD X‐ray detector by means of PIXE spectra

The efficiency of a silicon drift detector with ultrathin window was studied for energies between 0.27 and 25 keV. Experimental values of the X‐ray yields from samples of known stoichiometry were obtained by impact of 2 MeV protons. By using theoretical calculations of these yields the relative efficiency of the detector was evaluated. The results are compared with efficiency values obtained from the window transmission and the detector quantum efficiency. A quantitative analysis of a particle induced X‐ray emission spectrum for a reference sample was performed in order to evaluate the consistency of the data presented in this work. Copyright © 2013 John Wiley & Sons, Ltd.     

Heterodyne detection enhanced by quantum correlation

Heterodyne detectors as phase-insensitive(PI) devices have found important applications in precision measurements such as space-based gravitational-wave(GW) observation. However, the output signal of a PI heterodyne detector is supposed to suffer from signal-to-noise ratio(SNR) degradation due to image band vacuum and imperfect quantum efficiency. Here, we show that the SNR degradation can be overcome when the image band vacuum is quantum correlated with the input signal.We calculate the noise figure of the detector and prove the feasibility of heterodyne detection with enhanced noise performance through quantum correlation. This work should be of great interest to ongoing space-borne GW signal searching experiments.     

X-ray photon-counting detector based on a micro-channel plate for pulsar navigation

The pulse time of arrival (TOA) is a determining parameter for accurate timing and positioning in X-ray pulsar navigation. The pulse TOA can be calculated by comparing the measured arrival time with the predicted arrival time of the X-ray pulse for pulsar. In this study, in order to research the measurement of pulse arrival time, an experimental system is set up. The experimental system comprises a simulator of the X-ray pulsar, an X-ray detector, a time-measurement system, and a data-processing system. An X-ray detector base is proposed on the basis of the micro-channel plate (MCP), which is sensitive to soft X-ray in the 1–10 keV band. The MCP-based detector, the structure and principle of the experimental system, and results of the pulse profile are described in detail. In addition, a discussion of the effects of different X-ray pulse periods and the quantum efficiency of the detector on pulse-profile signal-to-noise ratio (SNR) is presented. Experimental results reveal that the SNR of the measured pulse profile becomes enhanced as the quantum efficiency of the detector increases. The SNR of the pulse profile is higher when the period of the pulse is smaller at the same integral.     

量子密钥分配系统中的通信速率和误码率

基于通信速率和误码率在量子保密通信研究中的重要性, 采用1.55 μm上转换单光子探测器, 分析其量子效率随抽运功率的变化关系, 得出1.55 μm上转换单光子探测器较传统的铟镓砷二极管具有较高的量子效率和较低暗计数的优势, 并根据通信距离、上转换单光子探测器的量子效率和暗计数之间建立一种平衡, 得出每种距离上探测器的优化方案; 在考虑个体攻击无量子记忆的条件下, 比较BB84协议, BBM92协议和差分相移协议的量子密钥分配(QKD)系统的安全通信速率和误码率随通信距离的变化关系, 得出了差分相移键控协议的量子密钥分配系统是一个非常实用的, 通信距离大于200 km的很有吸引力的长距离量子密钥分配系统。     

High-performance integrating infrared detector

Improvement in the performance of a Si: P integrating infrared (IR) detector are described. The detector has the structure of a p-i-n diode but the mode of IR detection involves photoemission of charge stored in localized impurity states in the i-region at low temperatures. After IR exposure, the remaining occupied localized states are field ionized. In order to measure the remaining charge, the transient field ionization current is digitized and integrated. Increased quantum efficiency is obtained by increasing the photosensitive i-region thickness and impurity concentration. With increasing impurity concentration, the quantum efficiency of a 110 μm thick detector can be increased from 0.5% to about 70% in the neighborhood of 27 μm while the maximum charge storage time (IR integration time) decreased from more than 12 h to about l s.     

谐振腔提高横向光电效应的量子效率

根据位置敏感探测器的原理,设计了p-i-n型的谐振腔结构,研究谐振腔提高横向光电效应的量子效率。以一维缺陷光子晶体作为顶部光学镜,底部为分布式Bragg反射镜(DBR),中间为激活介质谐振腔。利用传输矩阵法计算了一维缺陷光子晶体的透射特性。由于顶部和底部结构的高反作用,一维缺陷光子晶体的透射谐振导模将被有效地限制在激活介质中。通过对谐振腔模型的分析,得出了激活介质的量子效率,并进行了数值仿真。结果表明,一维缺陷光子晶体的谐振导模能有效提高谐振腔中激活介质的量子转换效率。     

基于热敏超导边界转变传感的单光子探测技术

单光子探测是实现光量子信息处理的关键技术之一。基于热敏超导边界转变传感的单光子探测技术以其独有的极低的暗计数率、极高的量子探测效率和极强的光子数分辨能力而倍受关注。对比于其他的几种单光子探测技术,如光电倍增管、工作于盖革模式的雪崩二极管和超导纳米线等,本文将从其探测原理、实验样品制备和信号采集处理方法等方面出发,对基于热敏超导边界转变传感单光子探测技术研究的历史、现状进行综述,进而展望其未来可能的发.     

High-detective-quantum-efficiency fast-electron detector for electron energy loss spectroscopy

In order to increase the sensitivity of the parallel electron detector used in electron energy loss spectroscopy (EELS), we have developed a direct electron exposed detector, based on a photodiode array (PDA). This work investigates the performance of this detector at 100 keV incident electrons in terms of the detective quantum efficiency (DQE), the modulation transfer function (MTF) and radiation damage.     

Entanglement Purification of Nonlocal Quantum‐Dot‐Confined Electrons Assisted by Double‐Sided Optical Microcavities

A nondestructive parity‐check detector (PCD) scheme for two single‐electron quantum dots embedded in double‐sided optical microcavities is presented here. Using a polarization‐entangled photon pair, the PCD works in a parallel style and is robust to the phase fluctuation of the optical path length. In addition, based on this nondestructive PCD, an economic entanglement purification protocol for electron pairs is presented. The parties in quantum communication can increase the purification efficiency and simultaneously decrease the quantum source consumed for some particular fidelity thresholds. Therefore, this protocol has good applications in the future quantum communication and distributed quantum networks.     

单光子探测技术

近年来,以量子密钥分配为代表的各种量子信息技术应用获得了飞速发展,这些应用对单光子探测器的性能提出了非常苛刻的要求,以光电倍增管和雪崩光电二极管为代表的传统单光子探测器件已经无法满足需求。在此背景下,出现了以超导单光子探测器为代表的新型低温单光子探测器件,其性能比现有商用单光子探测器有了本质性的提升。本文综述了迄今为止各种类型的单光子探测器,并指出各自在量子信息技术应用中的优势和不足之处以及发展方向。