Scientific Publications

True Random Number Generation in an Optical I/Q Modulator

Title

True Random Number Generation in an Optical I/Q Modulator

Authors

Dinka Milovančev, Nemanja Vokić, Christoph Pacher, Hannes Hübel, and Bernhard Schrenk.

Abstract

We re-use a polarization-multiplexed I/Q modulator to acquire the quantum randomness of its seed laser light for the purpose of quantum random number generation. We obtain 9×10^4 256-bit AES keys/second after randomness extraction. Time-interleaved random number generation is demonstrated for PM-QPSK transmission.

Venue

European Conference on Optical Communicatios – ECOC 2020

Place and Date

6 – 10 Dec. 2020, hosted in Belgium, but 100% virtual

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Towards Integrating True Random Number Generation in Coherent Optical Transceivers

Title

Towards Integrating True Random Number Generation in Coherent Optical Transceivers

Authors

Dinka Milovančev, Nemanja Vokić, Christoph Pacher, Imran Khan, Christoph Marquardt, Winfried Boxleitner, Hannes Hübel, and Bernhard Schrenk.

Abstract

The integration of quantum communication functions often requires dedicated opto-electronic components that do not bode well with the technology roadmaps of telecom systems. We investigate the capability of commercial coherent transceiver sub-systems to support quantum random number generation next to classical data transmission, and demonstrate how the quantum entropy source based on vacuum fluctuations can be potentially converted into a true random number generator for this purpose. We discuss two possible implementations, building on a receiver- and a transmitter-centric architecture. In the first scheme, balanced homodyne broadband detection in a coherent intradyne receiver is exploited to measure the vacuum state at the input of a 90-degree hybrid. In our proof-ofprinciple demonstration, a clearance of >2 dB between optical and electrical noise is obtained over a wide bandwidth of more than 11 GHz. In the second scheme, we propose and evaluate the re-use of monitoring photodiodes of a polarization-multiplexed inphase/quadrature modulator for the same purpose. Time-interleaved random number generation is demonstrated for 10 Gbaud polarizationmultiplexed quadrature phase shift keyed data transmission. The availability of detailed models will allow to calculate the extractable entropy and we accordingly show randomness extraction for our two proof-of-principle experiments, employing a two-universal strong extractor.

Venue

IEEE Journal of Selected Topics in Quantum Electronics (JSTQE), vol. 26, no. 5, p. 6400608, Sep. 2020

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On the QKD Integration in Converged Fiber/Wireless Topologies for Secured, Low-Latency 5G/B5G Fronthaul

Title

On the QKD Integration in Converged Fiber/Wireless Topologies for Secured, Low-Latency 5G/B5G Fronthaul

Authors

Zavitsanos, D., Ntanos A., Giannoulis, G., & Avramopoulos, H.

Abstract

A research contribution focusing on the Quantum Key Distribution (QKD)-enabled solutions assisting in the security framework of an optical 5G fronthaul segment is presented. We thoroughly investigate the integration of a BB84-QKD link, operating at telecom band, delivering quantum keys for the Advanced Encryption Standard (AES)-256 encryption engines of a packetized fronthaul layer interconnecting multiple 5G terminal nodes. Secure Key Rate calculations are studied for both dedicated and shared fiber configurations to identify the attack surface of AES-encrypted data links in each deployment scenario. We also propose a converged fiber-wireless scenario, exploiting a mesh networking extension operated by mmWave wireless links. In addition to the quantum layer performance, emphasis is placed on the strict requirements of 5G-oriented optical edge segments, such as the latency and the availability of quantum keys. We find that for the dark fiber case, secret keys can be distilled at fiber lengths much longer than the maximum fiber fronthaul distance corresponding to the round-trip latency barrier, for both P2P and P2MP topologies. On the contrary, the inelastic Raman scattering makes the simultaneous transmission of quantum and classical signals much more challenging. To counteract the contamination of noise photons, a resilient classical/QKD coexistence scheme is adopted. Motivated by the recent advancements in quantum technology roadmap, our analysis aims to introduce the QKD blocks as a pillar of the quantum-safe security framework of the 5G/B5G-oriented fronthaul infrastructure.

Venue

Applied Sciences Journal, Volume 10, Issue 15, July 2020

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Adding Artificial Noise for Dynamic Code Rate Matching in Continuous-Variable Quantum Key Distribution

Title

Adding Artificial Noise for Dynamic Code Rate Matching in Continuous-Variable Quantum Key Distribution

Authors

S. Kreinberg, I. Koltchanov, A. Richter

Abstract

CV-QKD over long distances requires high reconciliation efficiencies, hence matching error correction code rate vs. SNR. For time-varying quantum channels, we achieve this by adding a controlled amount of digital noise to the measured data.

Venue

CLEO 2020

Place and Date

All-virtual, web conference format 11 – 15 May 2020

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Modelling Weak-Coherent QKD Systems Using a Classical Simulation Framework

Title

Modelling Weak-Coherent QKD Systems Using a Classical Simulation Framework

Authors

S. Kreinberg, P. Novik, I. Koltchanov, A. Richter

Abstract

We demonstrate how an existing simulation framework for modelling classical optical systems can be utilized for simulations of weak-coherent QKD links.

Venue

CLEO 2020

Place and Date

All-virtual, web conference format 11 – 15 May 2020

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Monolithically integrated differential phase shift transmitter for quantum key distribution

Title

Monolithically integrated differential phase shift transmitter for quantum key distribution

Authors

Ozan Çirkinoglu, Rui Santos, Kevin A. Williams, Xaveer J.M. Leijtens

Abstract

An integrated differential phase shift QKD transmitter, which consist of a distributed Bragg reflector laser, a phase modulator, and Mach-Zehnder modulator sections for pulse carving and optical attenuation has been designed and fabricated. Initial characterization shows single mode operation of the laser with a linewidth around 2 MHz, and an achievable optical attenuation of more than 60 dB.

Venue

22nd European Conference on Integrated Optics, 2020 (ECIO)

Place and date

Online, 23 – 24 June 2020

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An InP-based integrated modulated coherent state source for differential phase shift quantum key distribution

Title

An InP-based integrated modulated coherent state source for differential phase shift quantum key distribution

Authors

Ozan Çirkinoglu, Rui Santos, Kevin A. Williams, Xaveer J.M. Leijtens

Abstract

A low-cost integrated differential phase shift QKD transmitter, which consist of a distributed Bragg reflector laser, a phase modulator, and Mach-Zehnder modulator sections for pulse carving and optical attenuation is presented. Initial characterization results of the laser, and the modulator sections are demonstrated.

Venue

24th annual IEEE Photonics Benelux Symposium 2019

Place and Date

Netherlands, Amsterdam, 21 – 22 November 2019

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Differential Phase-Shift QKD in a 2:16-Split Lit PON with 19 Carrier-Grade Channels

Title

Differential Phase-Shift QKD in a 2:16-Split Lit PON with 19 Carrier-Grade Channels

Authors

N. Vokić, D. Milovančev, B. Schrenk, M. Hentschel, and H. Hübel

Abstract

We investigate the practical network integration of differential phase shift quantum key distribution following a cost-optimized deployment scheme where complexity is off-loaded to a centralized location. User terminal equipment for quantum state preparation at 1 GHz symbol rate is kept technologically lean through use of a directly-modulated laser as optical encoder. Integration in a passive optical network infrastructure is experimentally studied for legacy and modern optical access standards. We analyze the implications that result from Raman scattering arising from different spectral allocations of the classical channels in the O-, S-, C- and L-band, and prove that the quantum channel can co-exist with up to 19 classical channels of a fully-loaded modern access standard. Secure-key generation at a rate of 5.1×10 −7 bits/pulse at a quantum bit error ratio of 3.28% is obtained over a 13.5 km reach, 2:16 split passive network configuration. The high power difference of 93.8 dB between launched classical and quantum signals in the lit access network leads to a low penalty of 0.52% in terms of error ratio.

Venue

IEEE Journal Selected Topics in Quantum Electronics

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11.2 Tb/s Classical Channel Coexistence with DV-QKD over a 7-Core Multicore Fiber

Title 

11.2 Tb/s Classical Channel Coexistence with DV-QKD over a 7-Core Multicore Fiber

Author

E. Hugues-Salas, O. Alia, R. Wang, K. Rajkumar, G. T. Kanellos, R. Nejabati and D. Simeonidou

Abstract

The feasibility of transmitting discrete-variable quantum key distribution channels with carrier-grade classical optical channels over multicore fibers is experimentally explored in terms of achievable quantum bit error rates, secret key rates as well as classical signal bit error rates. A coexistence transmission record of 11.2Tb/s is achieved for the classical channels simultaneously with a DV-QKD channel over a 1km-long 7-core multicore fiber. Coexistence over the same multicore fiber core is identified as a dominant factor for the performance of the quantum channel requiring optical bandpass filtering of 17nm for the quantum channel to avoid the effect of Raman noise. Also, counter-propagation of classical channels and quantum channels probe more tolerance to noise proliferation than co-propagation. In addition, the performance of the quantum channel is maintained when more than three cores are used for the classical channels. Furthermore, by adding a second DV-QKD channel in the multicore fiber, the simultaneous transmission of classical channels as well as the generation of quantum-secured keys of two QKD channels is achieved with an operational range of 10dBs of launched power into the MCF.

Venue

IEEE Journal of Lightwave Technology

 

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Compact, low-threshold squeezed light source

Title

Compact, low-threshold squeezed light source

Authors

J. Arnbark, C. S. Jacobsen, R. B. Andrade, X. Guo, J. S. Neergaard-Nielsen, U. L. Andersen, T. Gehring

Abstract

Strongly squeezed light finds many important applications within the fields of
quantum metrology, quantum communication and quantum computation. However, due to the
bulkiness and complexity of most squeezed light sources of today, they are still not a standard tool
in quantum optics labs. We have taken the first steps in realizing a compact, high-performance
1550 nm squeezing source based on commercially available fiber components combined with
a free-space double-resonant parametric down-conversion source. The whole setup, including
single-pass second-harmonic generation in a waveguide, fits on a 30 cm×45 cm breadboard and
produces 9.3 dB of squeezing at a 5 MHz sideband-frequency. The setup is currently limited
by phase noise, but further optimization and development should allow for a 19″ sized turn-key
squeezing source capable of delivering more than 10 dB of squeezing.

Venue

Optics Express, vol 27

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