Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Optical Fiber Communication Conference

A resource-effective QKD field-trial in Padua with the iPOGNAC encoder

Marco Avesani, Luca Calderaro, Giulio Foletto, Costantino Agnesi, Francesco Picciariello, Francesco B. L. Santagiustina, Alessia Scriminich, Andrea Stanco, Francesco Vedovato, Mujtaba Zahidy, Giuseppe Vallone, Paolo Villoresi

Published Jan 1, 2021• 5 citations
Publisher

Abstract

We describe a novel low-error and calibration-free polarization encoder for Quantum Key Distribution, called iPOGNAC. The device, together with the Qubit4Sync synchronization, has been used to realize a resource-effective QKD field-trial in Padua, Italy.
DOI
10.1364/ofc.2021.f4e.3

Related papers

QKD field-trial in Padua: a resource-effective implementation with the iPOGNAC encoder

Marco Avesani, Luca Calderaro, Giulio Foletto +9 more

Quantum key distribution (QKD) is one of the most mature among the quantum technologies that allows two remote users to generate secret keys with unconditional security. To increase its adoption, simple, low-cost, and robust systems are necessary, together with demonstrations in real environments. Here, we present a QKD field-trial over optical fibers deployed in the city center of Padua, Italy. Our system exploits two key technologies developed by our group: a low-error, self-stabilized polarization encoder, called iPOGNAC, and a novel synchronization technique, called Qubit4Sync, which allows us to minimize the experimental complexity of our system.

Quantum Computing, Communication, and Simulation•Mar 2, 2022•0 citations

Resource-effective quantum key distribution: a field trial in Padua city center

Marco Avesani, Luca Calderaro, Giulio Foletto +9 more

Field trials are of key importance for novel technologies seeking commercialization and widespread adoption. This is also the case for quantum key distribution (QKD), which allows distant parties to distill a secret key with unconditional security. Typically, QKD demonstrations over urban infrastructures require complex stabilization and synchronization systems to maintain a low quantum bit error and high secret key rates over time. Here we present a field trial that exploits low-complexity self-stabilized hardware and a novel synchronization technique, to perform QKD over optical fibers deployed in the city center of Padua, Italy. Two techniques recently introduced by our research group are evaluated in a real-world environment: the iPOGNAC polarization encoder was used for preparation of the quantum states, while temporal synchronization was performed with the Qubit4Sync algorithm. The results here presented demonstrate the validity and robustness of our resource-effective QKD system, which can be easily and rapidly installed in an existing telecommunication infrastructure, thus representing an important step towards mature, efficient, and low-cost QKD systems.

arXiv:2012.08457•Optics Letters•Apr 28, 2021•41 citations

Time-bin Quantum Key Distribution exploiting the iPOGNAC polarization moulator and Qubit4Sync temporal synchronization

Costantino Agnesi, Davide Scalcon, Marco Avesani +5 more

Here we present cross-encoded Quantum Key Distribution where state encoding is performed with a self-compensating and calibration-free polarization modulator, while transmission is performed in time-bin encoding resistant to perturbances from the fiber channel.

Optical Fiber Communication Conference•Jan 1, 2022•0 citations

A Versatile and Low-Error Polarization Encoder for Quantum Communications

Costantino Agnesi, Marco Avesani, Federico Berra +7 more

In addition to stable, low-error and calibration-free polarization modulation, the iPOGNAC encoder can be promptly reconfigured for time-bin encoding, intensity modulation, and operations at different wavelengths. An overview of these applications and results is given.

Quantum 2.0 Conference and Exhibition•Jan 1, 2023•1 citation

GHz-rate polarization-based QKD system for fiber and satellite applications

Matías Rubén Bolaños, Edoardo Rossi, Federico Berra +9 more

Quantum key distribution (QKD) leverages the principles of quantum mechanics to exchange a secret key between two parties. Despite its promising features, QKD also faces several practical challenges such as transmission loss, noise in quantum channels and finite key size effects. Addressing these issues is crucial for the large-scale deployment of QKD in fiber and satellite networks. In this paper, we present a 1550 nm QKD system realizing the efficient-BB84 protocol and based on the iPOGNAC scheme. The system achieved repetition rates up to 1.5~GHz and showed an intrinsic QBER of $\sim 0.4\%$. The system was first tested on a laboratory fiber link and then on an intermodal link in the field, consisting of both deployed fiber and a 620 m free-space channel. The experiment was performed in daylight conditions, exploiting the Qubit4Sync synchronization protocol. With this trial, we achieved a new benchmark for free-space BB84 QKD systems by generating a sustained secret key rate (SKR) above 1~Mb/s for 1 hour. Finally, exploiting a recently discovered finite-size bound, we achieved a secure key rate of about 10 Mb/s at low losses (5 dB), and around 6.5~kb/s in the high-loss (38.5 dB), low block length ($N=10^4$) regime. The latter results demonstrate the system's suitability for highly lossy and time-constrained scenarios such as QKD from low Earth orbit satellites.

quant-pharXiv:2602.08908•Optica Quantum•Feb 10, 2026•0 citations

A quantum key distribution network in the metropolitan area of Padova

Marco Avesani, Giulio Foletto, Matteo Padovan +13 more

One of the most advanced technologies within the field of quantum mechanics is quantum key distribution (QKD), which allows the secure generation of secret keys among remote users. In order for QKD to be more widely adopted, it must be integrated into existing classical communication systems. However, this can be difficult due to the use of various technologies and channels in deployed networks. Recently, we developed a QKD network in the metropolitan area of Padova, which connects various nodes across the city through a combination of fiber and free-space links. By utilizing a modular design based on the iPOGNAC encoder and the Qubit4Sync method, we have realized portable and adaptable systems that operate in the C and O bands. This allowed us to deploy and test the compatibility of both research and commercial QKD systems by ThinkQuantum with classical communication over a variety of links, as well as their ability to switch between free-space and fiber connections. Finally, we developed and experimentally implemented complex network configurations such as star networks, where a fiber-based transmitter and free-space transmitter could operate with a single receiver.

Quantum Computing, Communication, and Simulation•Mar 8, 2023•4 citations
Quantum key distribution (QKD) is one of the most mature among the quantum technologies that allows two remote users to generate secret keys with unconditional security. To increase its adoption, simple, low-cost, and robust systems are necessary, together with demonstrations in real environments. Here, we present a QKD field-trial over optical fibers deployed in the city center of Padua, Italy. Our system exploits two key technologies developed by our group: a low-error, self-stabilized polarization encoder, called iPOGNAC, and a novel synchronization technique, called Qubit4Sync, which allows us to minimize the experimental complexity of our system.
Field trials are of key importance for novel technologies seeking commercialization and widespread adoption. This is also the case for quantum key distribution (QKD), which allows distant parties to distill a secret key with unconditional security. Typically, QKD demonstrations over urban infrastructures require complex stabilization and synchronization systems to maintain a low quantum bit error and high secret key rates over time. Here we present a field trial that exploits low-complexity self-stabilized hardware and a novel synchronization technique, to perform QKD over optical fibers deployed in the city center of Padua, Italy. Two techniques recently introduced by our research group are evaluated in a real-world environment: the iPOGNAC polarization encoder was used for preparation of the quantum states, while temporal synchronization was performed with the Qubit4Sync algorithm. The results here presented demonstrate the validity and robustness of our resource-effective QKD system, which can be easily and rapidly installed in an existing telecommunication infrastructure, thus representing an important step towards mature, efficient, and low-cost QKD systems.
Quantum key distribution (QKD) leverages the principles of quantum mechanics to exchange a secret key between two parties. Despite its promising features, QKD also faces several practical challenges such as transmission loss, noise in quantum channels and finite key size effects. Addressing these issues is crucial for the large-scale deployment of QKD in fiber and satellite networks. In this paper, we present a 1550 nm QKD system realizing the efficient-BB84 protocol and based on the iPOGNAC scheme. The system achieved repetition rates up to 1.5~GHz and showed an intrinsic QBER of ∼0.4%\sim 0.4\%∼0.4%. The system was first tested on a laboratory fiber link and then on an intermodal link in the field, consisting of both deployed fiber and a 620 m free-space channel. The experiment was performed in daylight conditions, exploiting the Qubit4Sync synchronization protocol. With this trial, we achieved a new benchmark for free-space BB84 QKD systems by generating a sustained secret key rate (SKR) above 1~Mb/s for 1 hour. Finally, exploiting a recently discovered finite-size bound, we achieved a secure key rate of about 10 Mb/s at low losses (5 dB), and around 6.5~kb/s in the high-loss (38.5 dB), low block length (N=104N=10^4N=104) regime. The latter results demonstrate the system's suitability for highly lossy and time-constrained scenarios such as QKD from low Earth orbit satellites.
One of the most advanced technologies within the field of quantum mechanics is quantum key distribution (QKD), which allows the secure generation of secret keys among remote users. In order for QKD to be more widely adopted, it must be integrated into existing classical communication systems. However, this can be difficult due to the use of various technologies and channels in deployed networks. Recently, we developed a QKD network in the metropolitan area of Padova, which connects various nodes across the city through a combination of fiber and free-space links. By utilizing a modular design based on the iPOGNAC encoder and the Qubit4Sync method, we have realized portable and adaptable systems that operate in the C and O bands. This allowed us to deploy and test the compatibility of both research and commercial QKD systems by ThinkQuantum with classical communication over a variety of links, as well as their ability to switch between free-space and fiber connections. Finally, we developed and experimentally implemented complex network configurations such as star networks, where a fiber-based transmitter and free-space transmitter could operate with a single receiver.