Directly Phase-Modulated Light Source

Yuan, Zhiliang; Fröhlich, B.; Roberts, George L.; Dynes, J. F.; Shields, A. J.

doi:10.1103/physrevx.6.031044

Cited by 57 publications

(52 citation statements)

References 50 publications

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“…In this work, we present a QKD transmitter chip that exploits the direct phase modulation approach recently introduced in bulk optics transmitters 16 . This approach combines gain-switching, injection locking and ultra-fast phase modulation of the seedlaser to generate chirp free pulses and to realize multi-level phase encoding without the need of high-speed modulators.…”

Section: Introductionmentioning

confidence: 99%

A modulator-free quantum key distribution transmitter chip

et al. 2019

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Quantum key distribution (QKD) has convincingly been proven compatible with real life applications. Its wide-scale deployment in optical networks will benefit from an optical platform that allows miniature devices capable of encoding the necessarily complex signals at high rates and with low power consumption. While photonic integration is the ideal route toward miniaturisation, an efficient route to high-speed encoding of the quantum phase states on chip is still missing. Consequently, current devices rely on bulky and high power demanding phase modulation elements which hinder the sought-after scalability and energy efficiency. Here we exploit a novel approach to high-speed phase encoding and demonstrate a compact, scalable and power efficient integrated quantum transmitter. We encode cryptographic keys on-demand in high repetition rate pulse streams using injection-locking with deterministic phase control at the seed laser. We demonstrate record secure-key-rates under multiprotocol operation. Our modulator-free transmitters enable the development of high-bit rate quantum communications devices, which will be essential for the practical integration of quantum key distribution in high connectivity networks.

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Section: Introductionmentioning

confidence: 99%

A modulator-free quantum key distribution transmitter chip

et al. 2019

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“…There are two approaches to increase the key generation rate. One is to increase the repetition rates of photon generation [10] and detection [11], which is inherently limited by dead times and jitter of the detectors [12]. The other approach is to exploit properties of photons besides the polarization to increase the dimensionality of the Hilbert space [13,14].…”

Section: Introductionmentioning

confidence: 99%

Large-alphabet quantum key distribution using spatially encoded light

Tentrup

Luiten²,

Meer

et al. 2019

New J. Phys.

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Most quantum key distribution protocols using a two-dimensional basis, such as HV polarization as first proposed by Bennett and Brassard in 1984, are limited to a key generation density of 1 bit per photon. We increase this key density by encoding information in the transverse spatial displacement of the used photons. Employing this higher-dimensional Hilbert space together with modern singlephoton-detecting cameras, we demonstrate a proof-of-principle large-alphabet quantum key distribution experiment with 1024 symbols and a shared information between sender and receiver of 7bit per photon.

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“…With respect to this, we note that gain-switched laser diodes are presently the de facto QKD light source, capable of naturally providing phase-randomised coherent pulses at a clock rate of up to 2.5 GHz. 134,135 Progress has also been made on enhancing the security of QKD by carefully examining source imperfections in implementations. Refs 136,137 studied the risk of Trojan horse attacks due to back reflections from commonly used optical components in QKD.…”

Section: Mdi-qkdmentioning

confidence: 99%

Practical challenges in quantum key distribution

Diamanti¹,

Lo²,

Qi³

et al. 2016

npj Quantum Inf

625

468

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Quantum key distribution (QKD) promises unconditional security in data communication and is currently being deployed in commercial applications. Nonetheless, before QKD can be widely adopted, it faces a number of important challenges such as secret key rate, distance, size, cost and practical security. Here, we survey those key challenges and the approaches that are currently being taken to address them. For thousands of years, human beings have been using codes to keep secrets. With the rise of the Internet and recent trends to the Internet of Things, our sensitive personal financial and health data as well as commercial and national secrets are routinely being transmitted through the Internet. In this context, communication security is of utmost importance. In conventional symmetric cryptographic algorithms, communication security relies solely on the secrecy of an encryption key. If two users, Alice and Bob, share a long random string of secret bits-the key-then they can achieve unconditional security by encrypting their message using the standard one-time-pad encryption scheme. The central question then is: how do Alice and Bob share a secure key in the first place? This is called the key distribution problem. Unfortunately, all classical methods to distribute a secure key are fundamentally insecure because in classical physics there is nothing preventing an eavesdropper, Eve, from copying the key during its transit from Alice to Bob. On the other hand, standard asymmetric or public-key cryptography solves the key distribution problem by relying on computational assumptions such as the hardness of factoring. Therefore, such schemes do not provide information-theoretic security because they are vulnerable to future advances in hardware and algorithms, including the construction of a large-scale quantum computer.

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Directly Phase-Modulated Light Source

Cited by 57 publications

References 50 publications

A modulator-free quantum key distribution transmitter chip

A modulator-free quantum key distribution transmitter chip

Large-alphabet quantum key distribution using spatially encoded light

Practical challenges in quantum key distribution

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