Abstract Quantum cryptography founded on the laws of physics could revolutionize way in which communication information is protected. Significant progresses long-distance quantum key distribution based discrete variables have led to secure real-world conditions being available. However, alternative approach implemented with continuous has not yet reached distance beyond 100 km. Here, we overcome previous range limitation by controlling system excess noise and report such a long...

We report a 100-MHz continuous-variable quantum key distribution (CV-QKD) experiment over 25-km fiber channel without sending local oscillator (LO). use "locally" generated LO and implement with 1-GHz shot-noise-limited homodyne detector to achieve high-speed measurement, we propose secure phase compensation scheme maintain low level of excess noise. These make high-bit-rate CV-QKD significantly simpler for larger transmission distances compared previous schemes in which both signals are...

We report the first continuous-variable quantum key distribution (CVQKD) experiment to enable creation of 1 Mbps secure rate over 25 km standard telecom fiber in a coarse wavelength division multiplexers (CWDM) environment. The result is achieved with two major technological advances: use GHz shot-noise-limited homodyne detector and implementation 50 MHz clock system. excess noise due photons from local oscillator classical data channels CWDM controlled effectively. note that experimental...

We report on what we believe is the first field implementation of a continuous-variable quantum key distribution (CV-QKD) network with point-to-point configuration. Four QKD nodes are deployed standard communication infrastructures connected commercial telecom optical fiber. Reliable exchange achieved in wavelength-division-multiplexing CV-QKD network. The impact complex and volatile environment excess noise investigated, since controlling reduction arguably major issue pertaining to...

Continuous-variable quantum key distribution (CVQKD) with a real local oscillator (LO) has been extensively studied recently due to its security and simplicity. In this paper, we propose novel implementation of high-key-rate CVQKD LO. Particularly, the help simultaneously generated reference pulse, phase drift signal is tracked in time then compensated. By utilizing polarization multiplexing techniques isolate pulse controlling intensity it, not only contamination from it suppressed, but...

It has been found that non-Gaussian operations can be applied to increase and distill entanglement between Gaussian entangled states. We propose here a method improve the performance of entanglement-based (EB) continuous-variable quantum-key-distribution protocol by using operation, in particular, subtraction which implemented under current technology easily. Security analysis shows operation well secure distance tolerable excess noise EB scheme also corresponding prepare-and-measure scheme.

Integrated quantum key distribution (QKD) systems based on photonic chips have high scalability and stability, are promising for further construction of global communications networks. On-chip light sources a critical component fully integrated QKD system; especially continuous-variable (CV-QKD) system coherent detection, which has extremely requirements the sources. Here, what we believe is first time, designed fabricated two on-chip tunable lasers CV-QKD, demonstrated high-performance...

Abstract Quantum key distribution (QKD) is one quantum technology that can provide secure encryption keys for data transmission. The secret rate (SKR) a core performance indicator in QKD, which directly determines the transmission of enciphered data. Here, first time, we demonstrate high-key-rate Gaussian-modulated continuous-variable QKD (CV-QKD) using telecom optical components. framework CV-QKD over these components constructed. Specifically, high-rate low-noise Gaussian modulation...

Abstract In continuous-variable quantum key distribution systems, reconciliation is a crucial step that significantly affects the secret rate (SKR). The rateless protocol based on Raptor codes can achieve high efficiency at low signal-to-noise ratios (SNRs). However, complexity of low-density parity-check (LDPC) used for precoding in limits speed reconciliation. this paper, we propose an adaptive by modifying codes. length random binary sequences increased because remove LDPC adds...

It has been found that non-Gaussian operations can be applied to increase and distill entanglement between Gaussian entangled states. We show the successful use of operation, in particular, photon subtraction on continuous-variable measurement-device-independent quantum key distribution (CV-MDI-QKD) protocol. The proposed method implemented based existing technologies. Security analysis shows operation remarkably maximal transmission distance CV-MDI-QKD protocol, which precisely make up for...

A suitable photon-subtraction operation can be exploited to improve the maximal transmission of continuous-variable quantum key distribution (CVQKD) in point-to-point communication. Unfortunately, faces solving improvement problem practical networks, where entangled source is located third part, which may controlled by a malicious eavesdropper, instead one trusted parts, Alice or Bob. In this paper, we show that solution come from using non-Gaussian operation, particular, provides method...

This paper deals with a channel-parameter estimation for continuous-variable quantum key distribution (CV-QKD) over satellite-to-submarine link. In particular, we focus on the channel transmittances and excess noise which are affected by atmospheric turbulence, surface roughness, zenith angle of satellite, wind speed, submarine depth, etc. The method is based proposed algorithms applied to low-Earth orbits using Monte Carlo approach. For light at 550 nm repetition frequency 1 MHz, effects...

Abstract In this paper, a practical continuous-variable quantum key distribution system is developed and it runs in the real-world conditions with 25 MHz clock rate. To reach high-rate, we have employed homodyne detector maximal bandwidth to 300 an optimal high-efficiency error reconciliation algorithm processing speed up Mbps. optimize stability of system, several techniques are developed, which include novel phase compensation algorithm, polarization feedback related method on modulators....

We propose a pilot-multiplexed continuous-variable quantum key distribution (CVQKD) scheme based on local oscillator (LLO). Our utilizes time-multiplexing and polarization-multiplexing techniques to dramatically isolate the signal from pilot, employs two heterodyne detectors separately detect adopts phase compensation method almost eliminate multifrequency jitter. In order analyze performance of our scheme, general LLO noise model is constructed. Besides modulation noise, photon-leakage...

We propose a long-distance continuous-variable measurement-device-independent quantum key distribution (CV-MDI-QKD) protocol with discrete modulation. This kind of discrete-modulated schemes have good compatibility efficient error correction code, which lead to higher reconciliation efficiency even at low signal-to-noise ratio (SNR). Security analysis shows that the proposed is secure against arbitrary collective attacks in asymptotic limit proper use decoy states. And using modulation,...

Passive-state-preparation (PSP) continuous-variable quantum key distribution (CVQKD) protocol explores the intrinsic field fluctuations of a thermal source. Compared with traditional Gaussian-modulated coherent-state CVQKD, it does not need active modulations and has promising applications in chip integration portable free-space distribution. In this Letter, we propose experimentally realize PSP CVQKD scheme transmitted local oscillator (LO) through fluctuating transmittance channel using an...

We propose and experimentally demonstrate a continuous-variable quantum key distribution (CV-QKD) protocol using dual-phase-modulated coherent states. show that the modulation scheme of our works equivalently to Gaussian-modulated coherent-states (GMCS) protocol, but shows better experimental feasibility in plug-and-play configuration. Besides, it waives necessity propagation local oscillator (LO) between legitimate users generates real LO for measurement. Our is proposed independent one-way...

The quantum network makes use of states to transmit data, which will revolutionize classical communication and allow for some breakthrough applications. Quantum key distribution (QKD) is one prominent application networks, can protect data transmission through mechanics. In this work, we propose an expandable cost-effective access network, in the round-trip structure travel a circle carry information, multi-band technique proposed support multi-user access. Based on realize secure sharing...

In Gaussian-modulated coherent-state quantum key distribution, the measurement of quadratures coherent states is performed by using a homodyne detector. However, conventional detectors usually suffer from narrow bands. We present method to design high-speed shot-noise-limited balanced A 300-MHz bandwidth detector experimentally tested and level shot noise 14 dB higher than electronic noise. The results show that with this potential GHz for continuous variable distribution at low ratio

We propose a scheme for continuous-variable quantum key distribution (CV-QKD) using the subcarrier multiplexing technique which was employed in microwave photonics. This allows of $N$ channels with independent Gaussian-modulated CV-QKD parallel one laser source and several phase modulators. analyze influence nonlinear signal mixing security asymptotic limit. Results indicate that by this technique, each channel will have non-Gaussian extra noise, resulting slight shortening maximum...

The continuous-variable quantum key distribution (CVQKD) schemes with discrete modulation are proposed to allow distributions of secret keys over long distance due the sharing data. However, nonorthogonal signal states in these can be discriminated by using receivers low error rates, which may incur state-discrimination (SD) attacks. We consider feasibility Eve's attacks on discrete-modulated CVQKD protocol based SD receiver. In particular, an intercept-resend attack is four-state receiver...

Practical security of the continuous-variable quantum key distribution (CVQKD) system with finite sampling bandwidth analog-to-digital converter (ADC) at receiver's side is investigated. We find that effects may decrease lower bound secret rate without awareness legitimate communicators. This leaves loopholes for Eve to attack system. In addition, this effect restrains linear relationship bit repetition system; subsequently, there a saturation value rate. To resist such kind effects, we...

For supporting practical quantum key distribution (QKD), it is critical to stabilize the physical parameters of signals, e.g., intensity, phase, and polarization laser so that such QKD systems can achieve better performance security. In this paper, an approach developed by integrating a support vector regression (SVR) model optimize security system. First, SVR learned precisely predict time-along evolutions signals. Second, predicted are employed as feedback control system for achieving...

For the maximum-likelihood parameter estimation (MPE) of continuous-variable quantum key distribution (CVQKD), it sacrifices partial when estimating channel parameters, and is varying, even slowly, legitimate communication parties must constantly exchange input signal output to update estimation. Therefore, MPE leads following problems in practical application: (a) achieved by randomly sampling states can not accurately reflect dynamic channel; (b) there exist a trade-off between secret rate...