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Measurement-device-independent quantum key distribution (MDI-QKD) eliminates all loopholes on detection. Previous experiments of time-bin phase-encoding MDI-QKD allow a factor of 3 4 loss in the final key for the incapability of identifying two successive detection events by a single photon detector. Here we propose a new scheme to realize the time-bin phase-encoding MDI-QKD. The polarization states are used to generate the time bins and the phase-encoding states. The factor of loss in the final key is eliminated by using four single photon detectors at the measurement site. We show the feasibility of our scheme with a proof-of-principle experimental demonstration. The phase reference frame is rotated extremely slowly with only passive stabilization measures. The quantum bit error rate can reach 0.8% in the 𝑍-basis and 26.2% in the 𝑋-basis.

Measurement-device-independent quantum key distribution (MDI-QKD) is immune to all security loopholes on detection. Previous experiments on MDI-QKD required spatially separated signal lasers and complicated stabilization systems. In this paper, we perform a proof-of-principle experimental demonstration of plug-andplay MDI-QKD over an asymmetric channel setting with a single signal laser in which the whole system is automatically stabilized in spectrum, polarization, arrival time, and phase reference. Both the signal laser and the single-photon detectors are in the possession of a common server. A passive timing-calibration technique is applied to ensure the precise and stable overlap of signal pulses. The results pave the way for the realization of a quantum network in which the users only need the encoding devices.

The correctness of measurement‐device‐independent quantum key distribution (MDI‐QKD) has been demonstrated in tremendous amount of researches. There is an interesting proposal which can collect all coincidences by transforming two pairs of orthogonal polarization states into the encoding states of MDI‐QKD. The attempt is meaningful. Here, based on this proposal, we realize a proof‐of‐principle demonstration. Only one phase modulator is applied to encode the qubits. The phase‐reference‐frame is aligned by modulating the phase modulator of the phase modulation unit. We modulate the signals into three intensities, and a secure key rate of 5.44×10−7 bits per pulse is successfully demonstrated. Our experimental system simplifies the encoding process and has the potential to implement the reference‐frame‐independent MDI‐QKD protocol.

Measurement of fast signal is getting more and more important in many fields. In this paper, we propose to detect a temporal signal based on the idea of computational ghost imaging (GI), which can greatly reduce requirements on bandwidth of detectors. In experiments, we implement retrieving of a temporal signal with time scale of 50ns using a detector of 1kHz bandwidth, which is much lower than the requirement on bandwidth of detector according to information theory. The performance of our technique are also investigated under different detection bandwidths.

We experimentally demonstrate a kind of high-quantum correlated, practical quantum random generation based on the quantum phase noise of a laser, which uniformly distributes in the range of (−𝜋, 𝜋] by driving the laser with a stream of narrow electrical pulses. We propose a working mode to further suppress the impact of phase drift after we use the passive measures (thermal and mechanical isolation) to slow it down. Moreover, a new method which ensures random numbers to be true representations of quantum characteristics is presented to quantify the quantum randomness. This scheme has an inherent advantage for multiplex generation.

Decoy state method could effectively enhance the performance of quantum key distribution (QKD) with practical phase randomized weak coherent source. Although active modulation of the source intensity is effective and has been implemented in many experiments, passive preparation of decoy states is also an important addition to the family of decoy state QKD protocols. In this paper, following the theory of Curty et al. [PRA, 81, 022310 (2010)], we experimentally demonstrate the phase-encoding passive-decoy-state QKD with only linear optical setups and threshold single photon detectors. In our experiment, two homemade independent pulsed lasers, with visibility of Hong-Ou-Mandel interference 0.53(±0.003), have been implemented and used to passively generate the different decoy states. Finally, secret key rate 1.5×10 −5 /pulse is obtained with 10km commercial fiber between Alice and Bob.