Simple and high-speed polarization-based QKD

Grünenfelder, Fadri; Boaron, Alberto; Rusca, Davide; Martin, Anthony; Zbinden, Hugo

doi:10.1063/1.5016931

Cited by 66 publications

(45 citation statements)

References 26 publications

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“…In this way we generate the three states required by the simplified three polarization state version of BB84 [21], with the key-generation basis Z = {|0 , |1 } where |0 := |L , |1 := |R , and the control state |+ of the X = {|+ , |− } basis.…”

Section: Setupmentioning

confidence: 99%

“…This has led, for example, to the introduction of selfcompensated modulators for different photonic degrees of freedom such as time-bin [18], mean photon number [19], and polarization [20], all based on Sagnac interferometric configurations. Also, simpler QKD protocols have been introduced such as a three-state and one-decoy state version of the BB84 protocol which simplifies the requirements of the quantum state encoder [21] and can provide higher rates in the finite-key scenario [22].…”

Section: Introductionmentioning

confidence: 99%

“…Polarization-encoded QKD in fiber-optic links has been studied to great extent, mainly encouraged by the simplicity of the receiver, which can be completely passive and requires only standard components [21,23,26,27]. Unfortunately, this type of link has an important drawback given by the natural birefringence of optical fibers, which causes the polarization state of transmitted photons to change continuously and in an unpredictable fashion [28].…”

Section: Introductionmentioning

confidence: 99%

“…Here we present a simple polarization encoded QKD experiment exploiting a 26 km fiber-optic link and using the simplified three-state and one-decoy (two intensity levels) protocol proposed by Grünenfelder et al [21]. The QKD source is comprised of the POGNAC polarization modulator, which exhibits high stability and a low intrinsic Quantum Bit Error Rate (QBER) [20].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Simple quantum key distribution with qubit-based synchronization and a self-compensating polarization encoder

Agnesi¹,

Avesani²,

Calderaro³

et al. 2020

Optica

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Widespread adoption of Quantum Key Distribution (QKD) in current telecommunication networks will require the development of simple, low cost and stable systems. Current QKD implementations usually include separate sub-systems to implement auxiliary tasks such as temporal synchronization and polarization basis tracking. Here we present a QKD system with polarization encoding that performs synchronization, polarization compensation and QKD with the same optical setup without requiring any changes or any additional hardware. Polarization encoding is performed by a self-compensating Sagnac loop modulator which exhibits high stability and the lowest intrinsic QBER ever reported by an active polarization source fully implemented using only commercial offthe-shelf components. We tested our QKD system over a fiber-optic channel, tolerating up to 43 dB of total losses and representing an important step towards technologically mature QKD systems. * These authors contributed equally to this work.

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Section: Setupmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Simple quantum key distribution with qubit-based synchronization and a self-compensating polarization encoder

Agnesi¹,

Avesani²,

Calderaro³

et al. 2020

Optica

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“…Despite polarization encoding being the predilected choice for free-space and satellite-based QKD experiments, few steps have been made to develop a simple and stable polarization state encoder. The use of inline Lithium Niobate (LiNbO 3 ) modulators has been an adopted solution [11,16], where the birefringence of the crystal is controlled by an external RF field. The applied voltage changes the index of refraction of both polarization modes differently, introducing a relative phase between each polarization, thereby modulating the polarization state.…”

Section: Introductionmentioning

confidence: 99%

All-fiber self-compensating polarization encoder for quantum key distribution

Agnesi¹,

Avesani²,

Stanco³

et al. 2019

Opt. Lett.

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Quantum Key Distribution (QKD) allows distant parties to exchange cryptographic keys with unconditional security by encoding information on the degrees of freedom of photons. Polarization encoding has been extensively used in QKD implementations along free-space, optical fiber and satellite-based links. However, the polarization encoders used in such implementations are unstable, expensive, complex and can even exhibit side-channels that undermine the security of the implemented protocol. Here we propose a self-compensating polarization encoder based on a Lithium Niobate phase modulator inside a Sagnac interferometer and implement it using only standard telecommunication commercial off-the-shelves components (COTS). Our polarization encoder combines a simple design and high stability reaching an intrinsic quantum bit error rate as low as 0.2%. Since realization is possible from the 800 nm to the 1550 nm band by using COTS, our polarization modulator is a promising solution for free-space, fiber and satellite-based QKD.

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Optimizing Decoy‐State Protocols for Practical Quantum Key Distribution Systems

Fan-Yuan

Wang

et al. 2021

Adv Quantum Tech

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The decoy-state protocol enables quantum key distribution (QKD) systems to achieve high performance without using the single-photon source. In the dozen years since the decoy-state protocol has been proposed, a series of advances in scheme design, finite-size analysis, system modelling, and parameter estimation has developed. Unfortunately, most advances are based on different starting points and lack a synthesis to figure out the optimal protocol of decoy-state method. Here, the advances in decoy-state method are reviewed and they are synthesized to compare the key-rate performance of 38 decoy-state protocols using the particle swarm optimization (PSO) algorithm. To form a guideline for practical QKD systems, the optimal decoy-state protocols are found with the change of five system parameters (the transmission loss, the block size of postprocessing, the misalignment-error probability, the dark-count probability, and the afterpulse rate). It is expected that this work can answer the questions of what the actual performance is for different decoy-state protocol in various scenarios and which decoy-state protocol is the optimal choice for various QKD systems.

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Simple and high-speed polarization-based QKD

Cited by 66 publications

References 26 publications

Simple quantum key distribution with qubit-based synchronization and a self-compensating polarization encoder

Simple quantum key distribution with qubit-based synchronization and a self-compensating polarization encoder

All-fiber self-compensating polarization encoder for quantum key distribution

Optimizing Decoy‐State Protocols for Practical Quantum Key Distribution Systems

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