qTReX : A semi-autonomous continuous-variable quantum key distribution system

Jain, Nitin; Chin, Hou-Man; Mani, Hossein; Bidstrup, Erik; Andersen, Ulrik L.; Gehring, Tobias

doi:10.1364/ofc.2022.m3z.2

Cited by 3 publications

(3 citation statements)

References 11 publications

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“…A further measurement set was taken on our semi-autonomous CV-QKD system [27] for a demonstration with a free-running system with a channel triggered Rx instead of an externally triggered one. The measurement was performed over 10 km of SMF and yielded 2.4 mPNU excess noise for a secret key fraction of roughly 0.0740 bits/symbol over 9 × 10 6 symbols with a modulation variance 3.5, assuming the same reconciliation efficiency of 0.95.…”

Section: Resultsmentioning

confidence: 99%

“…Initial testing was performed over 20 km of standard single mode fibre (SMF-28) with the DAQ in the Rx being externally triggered by the Tx. Another measurement for confirmation was performed over 10 km SMF, but this time without any external trigger; instead we used the DAQ channel itself as a trigger source [27]. Alice modulates symbols drawn at random from a Gaussian distribution at 20 Mbaud.…”

Section: Methodsmentioning

confidence: 99%

“…Firstly, the above mentioned methods require a discrete modulation format with well defined temporal features, which the CV-QKD system may not be implementing e.g. [21,27]. Secondly, the typical signal to noise ratio (SNR) of a quantum signal at the Rx is less than 0 dB [28,29] restricting the accuracy of those methods.…”

Section: Synchronizationmentioning

confidence: 99%

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Digital synchronization for continuous-variable quantum key distribution

Chin

Jain

Andersen

et al. 2022

Quantum Sci. Technol.

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Continuous variable quantum key distribution (CV-QKD) is a promising emerging technology for the distribution of secure keys for symmetric encryption. It can be readily implemented using commercial oﬀ-the-shelf optical telecommunications components. A key requirement of the CV-QKD receiver is the ability to measure the quantum states at the correct time instance and rate using the correct orthogonal observables, referred to as synchronization. We propose a digital synchronization procedure for a modern CV-QKD system with locally generated local oscillator for coherent reception. Our proposed method is modulation format independent allowing it to be used in a variety of CV-QKD systems. We experimentally investigate its performance with a Gaussian modulated CV-QKD system operating over a 10-20 km span of standard single mode ﬁbre. Since the procedure does not require hardware modiﬁcations it paves the way for cost-eﬀective QKD solutions that can adapt rapidly to changing environmental conditions.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Digital synchronization for continuous-variable quantum key distribution

Chin

Jain

Andersen

et al. 2022

Quantum Sci. Technol.

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Practical continuous-variable quantum key distribution with composable security

et al. 2022

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A quantum key distribution (QKD) system must fulfill the requirement of universal composability to ensure that any cryptographic application (using the QKD system) is also secure. Furthermore, the theoretical proof responsible for security analysis and key generation should cater to the number N of the distributed quantum states being finite in practice. Continuous-variable (CV) QKD based on coherent states, despite being a suitable candidate for integration in the telecom infrastructure, has so far been unable to demonstrate composability as existing proofs require a rather large N for successful key generation. Here we report a Gaussian-modulated coherent state CVQKD system that is able to overcome these challenges and can generate composable keys secure against collective attacks with N ≈ 2 × 108 coherent states. With this advance, possible due to improvements to the security proof and a fast, yet low-noise and highly stable system operation, CVQKD implementations take a significant step towards their discrete-variable counterparts in practicality, performance, and security.

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Continuous-variable quantum key distribution at 10 GBaud using an integrated photonic-electronic receiver

Hajomer,

Bruynsteen,

Derkach

et al. 2024

Optica

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Quantum key distribution (QKD) is a widely recognized application of quantum information theory, guaranteeing information-theoretically secure key exchange. However, commercial viability of QKD systems is currently impeded by issues such as scalability, network integration, and high manufacturing costs. Low-cost, high-volume production of photonic and electronic integrated circuits could be the breakthrough needed for broad-scale deployment of cutting-edge QKD systems. Here, we present a continuous-variable (CV) QKD system that is based on an integrated photonic-electronic receiver. It combines a silicon photonic integrated circuit, featuring a phase-diverse receiver, with custom-designed GaAs pHEMT transimpedance amplifiers. Operating at a classical telecom symbol rate of 10 GBaud, our QKD system generates high secret key rates - exceeding 0.7 Gb/s over a 5 km distance and 0.3 Gb/s over a 10 km. The secret keys are secure against collective attacks, even when accounting for finite-size effects in the parameter estimation, thanks to well-designed digital signal processing that enables broadband system operation. Our experiment sets a record for secure key exchange and paves the way for the implementation of real-time broadband CV-QKD systems.

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qTReX : A semi-autonomous continuous-variable quantum key distribution system

Abstract: Continuous-variable quantum cryptography can leverage existing telecommunication technology for solving the cryptographic task of secure key distribution. We present qTReX: A low-noise, highly stable, semi-autonomous prototype using optical coherent states for quantum key distribution.

Cited by 3 publications

References 11 publications

Digital synchronization for continuous-variable quantum key distribution

Digital synchronization for continuous-variable quantum key distribution

Practical continuous-variable quantum key distribution with composable security

Continuous-variable quantum key distribution at 10 GBaud using an integrated photonic-electronic receiver

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