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

arXiv:2207.12424 · Physical Review Applied

Quantum key Distribution with a Hand-Held Sender Unit

Gwenaëlle Vest, Peter Freiwang, Jannik Luhn, Tobias Vogl, Markus Rau, Lukas Knips, Wenjamin Rosenfeld, Harald Weinfurter

Published Aug 25, 2022• 33 citations
arXivHTMLPDF

Abstract

Living the revolution: Quantum key distribution over free-space channels offers a multitude of different application scenarios---provided it can be combined with conventional communication systems. This study presents a miniaturized sender module with all necessary optics fitting in the palm of a hand, and enabling quantum key exchange with a tracking receiver. Such rugged sender optics can facilitate many other use cases, e.g. by combining it with a free-space optical system in an urban area, or by using it aboard a microsatellite for global key exchange.

DOI
10.1103/physrevapplied.18.024067

Related papers

Integrated Quantum Key Distribution sender unit for hand-held platforms

Gwenaëlle Mélen

Mastering the generation, propagation and detection of electro-magnetic waves has enabled a technological breakthrough that has changed our entire society. World-wide communication through the telephone and the internet has become an integral part of our daily-life, which is expected to grow even further with the emergence of the internet of things. While secure communication was of concern mostly for governmental and financial institutions, digital security has now caught the attention of the general public. The weaknesses of cur- rent encryption protocols, such as the existence of back-doors or the predicted breakdown of popular algorithms such as RSA, reveal the need for alternative encryption schemes ensuring unconditional security on all types of devices. Quantum Key Distribution (QKD) has emerged as a powerful option to ensure a private communication between two users. Based on the laws of quantum mechanics, this class of protocols offers the possibility to detect the presence of a third party trying to intercept the key during its distribution, and even to quantify the amount of leaked information. While most research projects focus on long distance applications, little attention has been devoted to short distance schemes such as wireless payment, network access and authentication, which could highly benefit from QKD-enhanced security. This thesis focuses on the development of a miniature QKD sender add-on that could be embedded either in mobile devices or in existing optical communication platforms, thus allowing for a secure key exchange with a shared dedicated receiver over a free- space link. The proposed optics architecture (35 × 20 × 8 mm 3 ) is optimised for BB84-like protocols and uses an array of four Vertical-Cavity Surface-Emitting Lasers with highly similar properties to generate 40 ps long near-infrared faint coherent pulses at 100 MHz repetition rate. Under strong modulation, the polarisation of the pulses is not well defined and enables an external control of each diode’s emission by a wire-grid polariser. The four beams are spatially overlapped in a polarisation-insensitive femtosecond laser written waveguide array, and combined with a red beacon laser using an external beamsplitter to ensure a stable, synchronised optical link with the receiver. The complete module is compatible with current smartphone technology, allowing to run the classical post-processing over WLAN in the future. First tests with a free-space receiver indicate an average error ratio of 3.3 % and an asymptotic secure key rate of 54 kHz under static alignment. For the first time, a secure key exchange between a mobile platform held by a user and a receiver equipped with a dynamic alignment system could be demonstrated with an error ratio of 4.1 % and a secure key rate of 31 Hz. The further optimisation of the experimental parameters and the implementation of a decoy protocol will enhance the key generation rate as well as the general security of the system. The results of this thesis pave the way towards unprecedented security in wireless optical networks, as examplified for the communication between a mobile device and a dedicated receiver.

•Jan 1, 2016•1 citation

Integrated quantum key distribution sender unit for daily-life implementations

Gwenaëlle Mélen, Tobias Vogl, Markus Rau +4 more

Unlike currently implemented encryption schemes, Quantum Key Distribution provides a secure way of generating and distributing a key among two parties. Although a multitude of research platforms has been developed, the integration of QKD units within classical communication systems remains a tremendous challenge. The recently achieved maturity of integrated photonic technologies could be exploited to create miniature QKD add-ons that could extend the primary function of various existing systems such as mobile devices or optical stations. In this work we report on an integrated optics module enabling secure short-distance communication for, e.g., quantum access schemes. Using BB84-like protocols, Alice's mobile low-cost device can exchange secure key and information everywhere within a trusted node network. The new optics platform (35×20×8mm) compatible with current smartphone's technology generates NIR faint polarised laser pulses with 100MHz repetition rate. Fully automated beam tracking and live basis-alignment on Bob's side ensure user-friendly operation with a quantum link efficiency as high as 50% stable over a few seconds.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 16, 2016•14 citations

Handheld Quantum Key Distribution

Gwenaëlle Mélen, Peter Freiwang, Jannik Luhn +4 more

Using integrated optics enabled us to miniaturize QKD optics and to demonstrate handheld QKD. The robust device could be integrated with classical free space communication systems for links in metropolitan areas and to flying platforms.

Conference on Lasers and Electro-Optics•Jan 1, 2018•5 citations

Technologies for drone-based quantum key distribution

Daniel J. Gauthier, Roderick Cochran, Andrew J Conrad +8 more

Quantum key distribution is a well-established approach for sharing a classical key between two parties. In most cases, the parties are at fixed locations and use an optical fiber or free-space channel with fixed telescopes. To enable flexible and mobile quantum key distribution applications, we are developing a drone-based system. Here, the entire quantum transmitter and receiver system must have low size, weight, and power so that it can fly on medium-scale drones (Group 2, 21-55 lb gross takeoff weight). We will describe these key technologies and our current progress on achieving secure key exchange between drones.

Advanced Photon Counting Techniques•May 27, 2022•1 citation

Low cost, short range, free space quantum key distribution.

David Lowndes

We present a Quantum Key Distribution system comprising a hand held transmitter device (Alice) and a fixed terminal (Bob). The devices are highly asymmetrical with as much functionality as possible placed into the Bob terminal (a 4u 19in. rack) which is much less restricted on its size. The small size (80x50x10mm) and relatively low complexity will allow the hand held Alice to be cheaply mass produced and therefore widely available. A potential use for this technology would be as a method to allow the general public to benefit from a wider metropolitan or national QKD network by establishing key with trusted network nodes. The Alice device optics comprise 4 pulsed 300um LEDs behind polarizers to produce the photon states for the BB84 protocol. Light from the LEDs is combined and spatially filtered using a single mode fibre, the output of which is collimated by a lens at the optical output of the device. The device is currently controlled via USB by a PC or mobile phone. The Bob terminal is split into two modules; broadly categorized as “optical” and “processing”. The optical module contains beam splitters for state discrimination and photon detection. The processing module contains a PC, wireless router, time-tagging electronics and power supply. The modular approach allows for a flexible platform for different QKD experiments, for example change of wavelength or protocol would involve switching out only the optical module. This work forms part of the Quantum Communications hub and was carried out with EPSRC funding (Quantum Communications Hub, grant no. EP/M013472/1).

•Jan 1, 2016•0 citations

Optical Components and System for Free-Space Quantum Key Distribution

Chun Ju Youn, Haesin Ko, Byung‐Seok Choi +4 more

A free-space quantum key distribution guarantees unconditional communication security with various applications between distant parties. In this paper, we show the integrated optical components and modules for the free-space quantum key distribution. Also, a free-space quantum key distribution system using newly developed and integrated optical components is demonstrated.

Opto-Electronics and Communications Conference (OECC)•Jul 1, 2018•0 citations
Living the revolution: Quantum key distribution over free-space channels offers a multitude of different application scenarios---provided it can be combined with conventional communication systems. This study presents a miniaturized sender module with all necessary optics fitting in the palm of a hand, and enabling quantum key exchange with a tracking receiver. Such rugged sender optics can facilitate many other use cases, e.g. by combining it with a free-space optical system in an urban area, or by using it aboard a microsatellite for global key exchange.
Mastering the generation, propagation and detection of electro-magnetic waves has enabled a technological breakthrough that has changed our entire society. World-wide communication through the telephone and the internet has become an integral part of our daily-life, which is expected to grow even further with the emergence of the internet of things. While secure communication was of concern mostly for governmental and financial institutions, digital security has now caught the attention of the general public. The weaknesses of cur- rent encryption protocols, such as the existence of back-doors or the predicted breakdown of popular algorithms such as RSA, reveal the need for alternative encryption schemes ensuring unconditional security on all types of devices. Quantum Key Distribution (QKD) has emerged as a powerful option to ensure a private communication between two users. Based on the laws of quantum mechanics, this class of protocols offers the possibility to detect the presence of a third party trying to intercept the key during its distribution, and even to quantify the amount of leaked information. While most research projects focus on long distance applications, little attention has been devoted to short distance schemes such as wireless payment, network access and authentication, which could highly benefit from QKD-enhanced security. This thesis focuses on the development of a miniature QKD sender add-on that could be embedded either in mobile devices or in existing optical communication platforms, thus allowing for a secure key exchange with a shared dedicated receiver over a free- space link. The proposed optics architecture (35 × 20 × 8 mm 3 ) is optimised for BB84-like protocols and uses an array of four Vertical-Cavity Surface-Emitting Lasers with highly similar properties to generate 40 ps long near-infrared faint coherent pulses at 100 MHz repetition rate. Under strong modulation, the polarisation of the pulses is not well defined and enables an external control of each diode’s emission by a wire-grid polariser. The four beams are spatially overlapped in a polarisation-insensitive femtosecond laser written waveguide array, and combined with a red beacon laser using an external beamsplitter to ensure a stable, synchronised optical link with the receiver. The complete module is compatible with current smartphone technology, allowing to run the classical post-processing over WLAN in the future. First tests with a free-space receiver indicate an average error ratio of 3.3 % and an asymptotic secure key rate of 54 kHz under static alignment. For the first time, a secure key exchange between a mobile platform held by a user and a receiver equipped with a dynamic alignment system could be demonstrated with an error ratio of 4.1 % and a secure key rate of 31 Hz. The further optimisation of the experimental parameters and the implementation of a decoy protocol will enhance the key generation rate as well as the general security of the system. The results of this thesis pave the way towards unprecedented security in wireless optical networks, as examplified for the communication between a mobile device and a dedicated receiver.
Unlike currently implemented encryption schemes, Quantum Key Distribution provides a secure way of generating and distributing a key among two parties. Although a multitude of research platforms has been developed, the integration of QKD units within classical communication systems remains a tremendous challenge. The recently achieved maturity of integrated photonic technologies could be exploited to create miniature QKD add-ons that could extend the primary function of various existing systems such as mobile devices or optical stations. In this work we report on an integrated optics module enabling secure short-distance communication for, e.g., quantum access schemes. Using BB84-like protocols, Alice's mobile low-cost device can exchange secure key and information everywhere within a trusted node network. The new optics platform (35×20×8mm) compatible with current smartphone's technology generates NIR faint polarised laser pulses with 100MHz repetition rate. Fully automated beam tracking and live basis-alignment on Bob's side ensure user-friendly operation with a quantum link efficiency as high as 50% stable over a few seconds.
Quantum key distribution is a well-established approach for sharing a classical key between two parties. In most cases, the parties are at fixed locations and use an optical fiber or free-space channel with fixed telescopes. To enable flexible and mobile quantum key distribution applications, we are developing a drone-based system. Here, the entire quantum transmitter and receiver system must have low size, weight, and power so that it can fly on medium-scale drones (Group 2, 21-55 lb gross takeoff weight). We will describe these key technologies and our current progress on achieving secure key exchange between drones.
We present a Quantum Key Distribution system comprising a hand held transmitter device (Alice) and a fixed terminal (Bob). The devices are highly asymmetrical with as much functionality as possible placed into the Bob terminal (a 4u 19in. rack) which is much less restricted on its size. The small size (80x50x10mm) and relatively low complexity will allow the hand held Alice to be cheaply mass produced and therefore widely available. A potential use for this technology would be as a method to allow the general public to benefit from a wider metropolitan or national QKD network by establishing key with trusted network nodes. The Alice device optics comprise 4 pulsed 300um LEDs behind polarizers to produce the photon states for the BB84 protocol. Light from the LEDs is combined and spatially filtered using a single mode fibre, the output of which is collimated by a lens at the optical output of the device. The device is currently controlled via USB by a PC or mobile phone. The Bob terminal is split into two modules; broadly categorized as “optical” and “processing”. The optical module contains beam splitters for state discrimination and photon detection. The processing module contains a PC, wireless router, time-tagging electronics and power supply. The modular approach allows for a flexible platform for different QKD experiments, for example change of wavelength or protocol would involve switching out only the optical module. This work forms part of the Quantum Communications hub and was carried out with EPSRC funding (Quantum Communications Hub, grant no. EP/M013472/1).