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Selected Topics in Quantum Electronics, IEEE Journal of

Issue 3 • Date May-June 2015

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Displaying Results 1 - 15 of 15
  • Parallel Quantum Computing Teleportation for Spin Qubits in Quantum Dot and Microcavity Coupled System

    Article#: 6809850
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (303 KB) |  | HTML iconHTML  

    We investigate the possibility of achieving a nonlocal parallel quantum computation by using hyperentangled photon pairs, quantum-dot spins, and optical-microcavities. Exploiting a pair of hyperentangled photons, the two nonlocal parties in a quantum network can perform a deterministic hyper-controlled-Z gate operation on two spins. With the parallel quantum computation operation, two identical cluster states can be built up simultaneously in a quantum computation network between non-local parties. As the cluster state is universal substrate for one-way quantum computation, our scheme can provide a polynomial gain for the capacity and efficiency of long-distance quantum computation. For the ideal spin-cavity system, our scheme for the remote control operation between two spin-qubits is deterministic and this protocol can be well combined with the long-distance quantum repeater. We also discuss the feasibility and efficiency of our scheme, conclude that it is feasible with current technologies. View full abstract»

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  • Postprocessing of the Oblivious Key in Quantum Private Query

    Article#: 6600111
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3004 KB) |  | HTML iconHTML  

    Private query is a kind of cryptographic protocols to protect both users' privacies in their communication. For instance, Alice wants to buy one item from Bob's database. The aim of private query is to ensure that Alice can get only one item from Bob, and simultaneously, Bob cannot know which one was taken by Alice. In pursuing high security and efficiency, some quantum private query protocols were proposed. As a practical model, Quantum-Oblivious-Key-Transfer (QOKT)-based private query, which utilizes a QOKT protocol to distribute oblivious key between Alice and Bob and then applies the key to achieve the aim of private query, has drawn much attention. Here, we focus on postprocessing of the oblivious key, and the following two contributions are achieved. 1) We analyze three recently proposed dilution methods and find two of them have serious security loophole. That is, Alice can illegally obtain much additional information about Bob's database by multiple queries. For example, Alice can obtain the whole database, which contains 104 items, by only 53.4 queries averagely. 2) We present an effective error-correction method for the oblivious key, which can address the realistic scenario with channel noises and make QOKT-based private query more practical. View full abstract»

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  • InP-Based Single-Photon Detectors and Geiger-Mode APD Arrays for Quantum Communications Applications

    Article#: 3800112
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (8842 KB) |  | HTML iconHTML  

    To meet the increasing demand from quantum communications and other photon starved applications, we have developed various InP-based single-photon detectors, including discrete single-photon avalanche diodes (SPADs), negative feedback avalanche diodes (NFADs), and Geiger-mode avalanche photodiode (GmAPD) arrays. A large quantity of InP SPADs have been fabricated. Out of 1000 devices with a 25-μm active area diameter, operated under gated mode at temperature of 233 K, with a pulse repetition rate of 1 MHz and pulse width of 1 ns, the average dark count rate and afterpulsing probability are 30 kHz and 8 × 10-5, respectively. Smaller (16-μm active area diameter) and larger (40-μm active area diameter) discrete devices have been fabricated as well, and their performances are presented along with the 25-μm diameter devices. NFAD devices can operate in free running mode and photon detection efficiency of 10-15% can be achieved without applying any hold-off time externally. When the temperature decreases from 240 to 160 K, the noise equivalent power (NEP) decreasesfrom1.9 × 10-16 to 1.8 × 10-18WHz-1/2, with the activation energy being 0.2 eV. The very low NEP at 160 K makes NFAD devices an ideal choice for long distance, entanglement-based quantum key distributions. GmAPD arrays provide an enabling technology for many active optical applications, such as 3-D laser detection and ranging (LADAR) and photon starved optical communications. Both 32 × 32 and 128 × 32 GmAPD arrays have been fabricated with high performance and good uniformity. GmAPD focal plane arrays (FPAs) with framed readout mode have enabled very high-performance flash LADAR systems. GmAPD FPAs with asynchronous readout mode will enable high rate quantum key distributions and other quantum communications applications. View full abstract»

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  • Differential Phase-Shift Quantum Key Distribution Systems

    Article#: 6600207
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1944 KB) |  | HTML iconHTML  

    Differential phase-shift (DPS) quantum key distribution (QKD) is a unique QKD protocol that is different from traditional ones, featuring simplicity and practicality. This paper overviews DPS-QKD systems. View full abstract»

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  • Quantum Spread Spectrum Multiple Access

    Article#: 6400107
    Multimedia
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (779 KB) |  | HTML iconHTML  

    We describe a quantum multiple access scheme that can take separate single photon channels and combine them in the same path. We propose an add-drop multiplexer that can insert or extract a single photon into an optical fiber carrying the qubits of all the other users. The system follows the principle of code division multiple access, a spread spectrum technique widely used in cellular networks. View full abstract»

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  • InGaAs/InP Single-Photon Detector Gated at 1.3 GHz With 1.5% Afterpulsing

    Article#: 3800306
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1782 KB) |  | HTML iconHTML  

    We demonstrate a single-photon detector based on InGaAs/InP single-photon avalanche diodes (SPADs) sinusoidal-gated at 1.3 GHz with very low afterpulsing (about 1.5%), high dynamic range (maximum count rate is 650 Mcount/s), high photon detection efficiency (>30% at 1550 nm), low noise (per-gate dark count rate is 2.2 × 10-5), and low timing jitter (<;70 ps full-width at half-maximum). The SPAD is paired with a “dummy” structure that is biased in antiphase. The sinusoidal gating signals are cancelled by means of a common-cathode configuration and by adjusting the relative amplitude and phase of the signals biasing the two arms. This configuration allows us to adjust the gating frequency from 1 to 1.4 GHz and can be operated also in the so-called gate-free mode, with the gate sine-wave unlocked with respect to the light stimulus, resulting in a free-running equivalent operation of the InGaAs/InP SPAD with about 4% average photon detection efficiency at 1550 nm. View full abstract»

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  • Safeguarding Quantum Key Distribution Through Detection Randomization

    Article#: 6600309
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3599 KB) |  | HTML iconHTML  

    We propose and experimentally demonstrate a scheme to render the detection apparatus of a quantum key distribution system immune to the main classes of hacking attacks in which the eavesdropper explores the back-door opened by the single-photon detectors. The countermeasure is based on the creation of modes that are not deterministically accessible to the eavesdropper. We experimentally show that the use of beamsplitters and extra single-photon detectors at the receiver station passively creates randomized spatial modes that erase any knowledge the eavesdropper might have gained when using bright-light faked states. Additionally, we experimentally show a detector-scrambling approach where the random selection of the detector used for each measurement-equivalent to an active spatial mode randomization-hashes out the side-channel open by the detection efficiency mismatch-based attacks. The proposed combined countermeasure represents a practical and readily implementable solution against the main classes of quantum hacking attacks aimed on the single-photon detector so far, without intervening on the inner working of the devices. View full abstract»

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  • Field Test of Measurement-Device-Independent Quantum Key Distribution

    Article#: 6600407
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (2076 KB) |  | HTML iconHTML  

    The main type of obstacles of practical applications of quantum key distribution (QKD) network are various attacks on detection. Measurement-device-independent QKD (MDIQKD) protocol is immune to all these attacks, and thus, a strong candidate for network security. Recently, several proof-of-principle demonstrations of MDIQKD have been performed. Although novel, those experiments are implemented in the laboratory with secure key rates less than 0.1 b/s. Besides, they need manual calibration frequently to maintain the system performance. These aspects render these demonstrations far from practicability. Thus, justification is extremely crucial for practical deployment into the field environment. Here, by developing an automatic feedback MDIQKD system operated at a high clock rate, we perform a field test via deployed fiber network of 30 km total length achieving a 16.9 b/s secure key rate. The result lays the foundation for a global quantum network, which can shield from all the detection-side attacks. View full abstract»

    Open Access
  • Design and Evaluation of a Handheld Quantum Key Distribution Sender module

    Article#: 6600607
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1457 KB) |  | HTML iconHTML  

    Currently most quantum key distribution (QKD) experiments are focusing on efficient long-distance implementations. Yet the recent development of miniaturized photonic modules and integrated quantum optics circuits could open new perspectives toward secure short-distance communication for daily-life applications. Here, we present the design of a new integrated optics architecture with an effective size of 25 mm × 2 mm × 1 mm. Our objective is to obtain an ultraflat microoptics QKD add-on suitable for integration into handheld platforms such as smartphones. In this context, we evaluated the suitability of various optical subsystems. We tested an array of four vertical cavity surface emitting lasers (VCSEL) with highly similar emission properties capable of producing subnanosecond near-infrared pulses at 100-MHz repetition rate. As short pulses exhibit a low polarization degree, their polarization can be externally controlled by a micropolarizer array. The fabrication of such elements is quite straightforward using standard lithographic techniques and extinction ratios up to 29 dB have been measured. To guarantee spatial indistinguishability of the qubits, we investigate the option of using low-birefringence, single-mode waveguide array manufactured via femtosecond laser micromachining. View full abstract»

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  • Risk Analysis of Trojan-Horse Attacks on Practical Quantum Key Distribution Systems

    Article#: 6600710
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (4953 KB) |  | HTML iconHTML  

    An eavesdropper Eve may probe a quantum key distribution (QKD) system by sending a bright pulse from the quantum channel into the system and analyzing the back-reflected pulses. Such Trojan-horse attacks can breach the security of the QKD system, if appropriate safeguards are not installed or if they can be fooled by the Eve. We present a risk analysis of such attacks based on extensive spectral measurements, such as transmittance, reflectivity, and detection sensitivity of some critical components used in a typical QKD systems. Our results indicate the existence of wavelength regimes, where the attacker gains considerable advantage as compared to launching an attack at 1550 nm. We also propose countermeasures to reduce the risk of such attacks. View full abstract»

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  • Entanglement Distribution in Optical Networks

    Article#: 6400212
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1422 KB) |  | HTML iconHTML  

    The ability to generate entangled photon pairs over a broad wavelength range opens the door to the simultaneous distribution of entanglement to multiple users in a network by using centralized sources and flexible wavelength-division multiplexing schemes. Here, we show the design of a metropolitan optical network consisting of tree-type access networks, whereby entangled photon pairs are distributed to any pair of users, independent of their location. The network is constructed employing commercial off-the-shelf components and uses the existing infrastructure, which allows for moderate deployment costs. We further develop a channel plan and a network-architecture design to provide a direct optical path between any pair of users; thus, allowing classical and one-way quantum communication, as well as entanglement distribution. This allows the simultaneous operation of multiple quantum information technologies. Finally, we present a more flexible backbone architecture that pushes away the load limitations of the original network design by extending its reach, number of users and capabilities. View full abstract»

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  • The Error Tolerance Bound for Secure Multi-Qubit QKD Against Incoherent Attack

    Article#: 6600809
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (896 KB) |  | HTML iconHTML  

    The tolerance bound for quantum symbol error rate in a multi-qubit quantum key distribution system is derived in consideration of an incoherent attack on a single-photon quantum channel, where multi-qubit encoding and measurement can be applied to a single photon in combination of polarization, phase, and frequency modulations. This paper presents a solid theoretical evidence of a multiqubit gain in secrecy performance. View full abstract»

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  • Quantum Photonic Network: Concept, Basic Tools, and Future Issues

    Article#: 6400313
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (8266 KB)  

    We present practical GHz-clocked QKD systems, next generation entanglement QKD technologies, and QKD platform to manage the secure keys and to support a variety of applications. We then show the intrinsic limit of QKD, i.e., a key rate bound, and discuss how to realize the provable (information theoretic) security with a larger secrecy capacity over longer distances. In particular, we present a basic theory of physical layer cryptography, which characterizes the secrecy capacity, and engineers the tradeoff between the efficiency of reliable transmission and secrecy of communication. We introduce a concept to unify these schemes in photonic network, referred to as quantum photonic network. Future issues for realizing this new network paradigm are discussed. View full abstract»

    Open Access
  • Spatial Mode Side Channels in Free-Space QKD Implementations

    Article#: 6600905
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (502 KB) |  | HTML iconHTML  

    The quantum key distribution protocol uses one degree of freedom of a single quantum system to encode information. If this information has correlations with the system’s other degrees of freedom, or if the measurement efficiencies on the receiver side depend on them, a security loophole called side channel is created. An eavesdropper can exploit it to gain information without disturbing the system, and thus, without revealing the attack. Here, we analyze side channels in a free-space QKD sender and receiver implementation and focus especially on the dependencies and side channels for the spatial degree of freedom. View full abstract»

    Open Access
  • Enhancing Heralding Efficiency and Biphoton Rate in Type-I Spontaneous Parametric Down-Conversion

    Article#: 6400610
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (4501 KB) |  | HTML iconHTML  

    The nonlinear optical process of spontaneous parametric down-conversion (SPDC) is widely studied for applications in quantum information science due to its ability to produce two photons that can be entangled in many degrees of freedom. For applications in quantum communication, two metrics of this process are particularly important: heralding efficiency and total joint rate. Here, we derive expressions for both quantities for a variety of different beam geometries and frequencies. We pay specific attention to the spectrum of both biphotons and individual photons. We reveal the underlying mechanisms responsible for the spectral shape and show they differ for different geometries and frequencies. We then use these spectra to calculate heralding efficiency and joint count rate and examine how each of these metrics changes with different geometries, frequencies, spectral filtering, and beam parameters. Interestingly, we find very high heralding efficiencies are achievable for collinear geometries without spectral filtering, while noncollinear geometries require spectral filtering to achieve the same values. We also find that the spectrum is narrower for nondegenerate SPDC than for degenerate SPDC, leading to lower joint count rates and higher heralding efficiency in the former. In addition to the theory, we verify selected predictions with experimental results. View full abstract»

    Open Access

Aims & Scope

Papers published in the IEEE Journal of Selected Topics in Quantum Electronics fall within the broad field of science and technology of quantum electronics of a device, subsystem, or system-oriented nature.

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Meet Our Editors

Editor-in-Chief
John Cartledge
Queen's University