Proof-of-concept of real-world quantum key distribution with quantum frames

Lucio-Martinez, I.; Chan, P.C.H.; Mo, Xinxin; Hosier, Steve; Tittel, Wolfgang

doi:10.1088/1367-2630/11/9/095001

Cited by 75 publications

(79 citation statements)

References 37 publications

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“…Instead one can derive a lower bound Y (1) L for the single photon yield (used in Eq. (11)), which for the specific case of µ d2 = 0 is given by [47] where µ s = 0.5 is the mean photon number of the signal state. The right-hand sides of equations (11) and (13) now contain directly measurable values and thus allow us to calculate the upper bound on the error rate E…”

Section: G: Bounding the Single-photon Fidelity Using Decoy State Anamentioning

confidence: 99%

Spectral Multiplexing for Scalable Quantum Photonics using an Atomic Frequency Comb Quantum Memory and Feed-Forward Control

et al. 2014

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Future multi-photon applications of quantum optics and quantum information science require quantum memories that simultaneously store many photon states, each encoded into a different optical mode, and enable one to select the mapping between any input and a specific retrieved mode during storage. Here we show, with the example of a quantum repeater, how to employ spectrallymultiplexed states and memories with fixed storage times that allow such mapping between spectral modes. Furthermore, using a Ti:Tm:LiNbO3 waveguide cooled to 3 Kelvin, a phase modulator, and a spectral filter, we demonstrate storage followed by the required feed-forward-controlled frequency manipulation with time-bin qubits encoded into up to 26 multiplexed spectral modes and 97% fidelity.PACS numbers: 03.67. Hk, 42.50.Ex, 32.80.Qk, 78.47.jf Further advances towards scalable quantum optics [1,2] and quantum information processing [3,4] rely on joint measurements of multiple photons that encode quantum states (e.g. qubits) [3][4][5]. However, as photons generally arrive in a probabilistic fashion, either due to a probabilistic creation process or due to loss during transmission, such measurements are inherently inefficient. For instance, this leads to exponential scaling of the time required to establish entanglement, the very resource of quantum information processing, as a function of distance in a quantum relay [6]. This problem can be overcome by using quantum memories, which are generally realized through the reversible mapping of quantum states between light and matter [7,8]. For efficient operation, these memories must be able to simultaneously store many photon states, each encoded into a different optical mode, and subsequently (using feed-forward) allow selecting the mapping between input and retrieved modes (e.g., different spectral or temporal modes). This enables making several photons arriving at a measurement device indistinguishable, thereby rendering joint measurements deterministic. For instance, revisiting the example of entanglement distribution, a quantum relay supplemented with quantum memories changes it to a repeater and, in principle, the scaling from exponential to polynomial [4,9].Interestingly, for such multimode quantum memories to be useful, it is not necessary to map any input mode onto any retrieved (output) mode, but it often suffices if a single input mode, chosen once a photon is stored, can be mapped onto a specific output mode (e.g. characterized by the photon's spectrum and recall time) [4,10]. This ensures that the photons partaking in a joint measurement, each recalled from a different quantum memory, are indistinguishable, as required, e.g., for a Bell-state measurement. We emphasize that it does not matter if the device used to store quantum states also allows the mode mapping, or if the mode mapping is performed after recall using appended devices -we will refer to the system allowing storage and mode mapping as the memory.To date, most research assumes photons arriving at different times at the m...

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Section: G: Bounding the Single-photon Fidelity Using Decoy State Anamentioning

confidence: 99%

Spectral Multiplexing for Scalable Quantum Photonics using an Atomic Frequency Comb Quantum Memory and Feed-Forward Control

et al. 2014

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“…Active phase randomization is implemented to defend against attacks on the imperfect weak coherent sources. Key bits are encoded into polarization states of the weak coherent pulses by a polarization modulator (Pol-M), whose design is proposed in [30]. The schematic of the polarization modulator, consisting of an optical circulator, a phase modulator (labelled as PM-pol), and a Faraday mirror, is shown in FIG.…”

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confidence: 99%

Experimental Demonstration of Polarization Encoding Measurement-Device-Independent Quantum Key Distribution

et al. 2014

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We demonstrate the first implementation of polarization encoding measurement-deviceindependent quantum key distribution (MDI-QKD), which is immune to all detector side-channel attacks. Active phase randomization of each individual pulse is implemented to protect against attacks on imperfect sources. By optimizing the parameters in the decoy state protocol, we show that it is feasible to implement polarization encoding MDI-QKD over large optical fiber distances. A 1600-bit secure key is generated between two parties separated by 10 km of telecom fibers. Our work suggests the possibility of building a MDI-QKD network, in which complicated and expensive detection system is placed in a central node and users connected to it can perform confidential communication by preparing polarization qubits with compact and low-cost equipment. Since MDI-QKD is highly compatible with the quantum network, our work brings the realization of quantum internet one step closer. Quantum key distribution (QKD) allows two parties, normally referred to as Alice and Bob, to generate a private key even with the presence of an eavesdropper, Eve [1,2]. With perfect single photon sources and single photon detectors, the security of QKD is guaranteed by quantum mechanics [3]. However, the aforementioned perfect devices are not available today and the security of QKD cannot be guaranteed in real life implementation. For example, attenuated coherent laser pulses are commonly used in practical QKD setups, which makes the QKD system vulnerable to the photon number splitting (PNS) attack [4]. Fortunately, it has been shown that the unconditional security of QKD can still be assured with phase randomized weak coherent pulses [5]. Furthermore, by applying decoy state techniques [6], secure key rate can be dramatically increased in practical implementations [7]. Nonetheless, other imperfections in practical QKD systems still present loopholes that can be exploited by Eve to steal the secret key [8,9]. We remark that most of the identified security loopholes are due to imperfections in the detection systems [8].Much effort has been put to build loophole-free QKD systems with practical devices. On one hand, people have been trying to build a better model to understand all the imperfections in a QKD detection system [10], but it is almost impossible to guarantee that all the loopholes have been fixed. On the other hand, full device-independent QKD (DI-QKD) has been proposed to close all the loopholes due to devices' imperfections [11]. The security of DI-QKD relies on the violation of Bell's inequality and does not require any knowledge of how practical QKD devices work. However, the demand for single photon detectors with near unity detection efficiency and the low key rate make this protocol highly impractical [12].Fortunately, measurement-device-independent QKD (MDI-QKD), which removes all loopholes in detec- arXiv:1306.6134v2 [quant-ph]

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“…The details of the calculation can be found in (Lucio-Martinez et al (2009)). Equation 2 shows that the polarization of the reflected laser pulse varies as a function of ∆φ, which is determined by the modulation voltages applied to the phase modulator.…”

Section: Modulationmentioning

confidence: 99%

Quantum Key Distribution

Zeng¹

2010

Quantum Private Communication

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Proof-of-concept of real-world quantum key distribution with quantum frames

Cited by 75 publications

References 37 publications

Spectral Multiplexing for Scalable Quantum Photonics using an Atomic Frequency Comb Quantum Memory and Feed-Forward Control

Spectral Multiplexing for Scalable Quantum Photonics using an Atomic Frequency Comb Quantum Memory and Feed-Forward Control

Experimental Demonstration of Polarization Encoding Measurement-Device-Independent Quantum Key Distribution

Quantum Key Distribution

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