Luis Trigo Vidarte | LIP6 - Équipe QI

Experimental demonstration of Continuous-Variable Quantum Key Distribution with a silicon photonics integrated receiver

Wed, 25 Dec 2024 00:00:00 +0000

Quantum Key Distribution (QKD) is a prominent application in the field of quantum cryptography providing information-theoretic security for secret key exchange. The implementation of QKD systems on photonic integrated circuits (PICs) can reduce the size and cost of such systems and facilitate their deployment in practical infrastructures. To this end, continuous-variable (CV) QKD systems are particularly well-suited as they do not require single-photon detectors, whose integration is presently challenging. Here we present a CV-QKD receiver based on a silicon PIC capable of performing balanced detection. We characterize its performance in a laboratory QKD setup using a frequency multiplexed pilot scheme with specifically designed data processing allowing for high modulation and secret key rates. The obtained excess noise values are compatible with asymptotic secret key rates of 2.4 Mbit/s and 220 kbit/s at an emulated distance of 10 km and 23 km, respectively. These results demonstrate the potential of this technology towards fully integrated devices suitable for high-speed, metropolitan-distance secure communication.

QOSST : A Highly Modular Open Source Software for Continuous-Variable Quantum Key Distribution

Wed, 13 Nov 2024 00:00:00 +0000

Shaped Constellation Continuous Variable Quantum Key Distribution: Concepts, Methods and Experimental Validation

Thu, 01 Aug 2024 00:00:00 +0000

Quantum key distribution (QKD) enables the establishment of secret keys between users connected via a channel vulnerable to eavesdropping, with information-theoretic security, that is, independently of the power of a malevolent party (Scarani et al., 2009). QKD systems based on the encoding of the key information on continuous variables (CV), such as the values of the quadrature components of coherent states (Weedbrook et al., 2012), (Diamanti and Leverrier, 2015), present the major advantage that they only require standard telecommunication technology. However, the most general security proofs for CV-QKD required until now the use of Gaussian modulation by the transmitter, complicating practical implementations (Jouguet et al., 2013), (Zhang et al., 2020), (Jain et al., 2022). Here, we experimentally implement a protocol that allows for arbitrary, Gaussian-like, discrete modulations, whose security is based on a theoretical proof that applies generally to such situations (Denys et al., 2021). These modulation formats are compatible with the use of powerful tools of coherent optical telecommunication, allowing our system to reach an estimated performance of tens of megabit per second secret key rates over 25 km.

QOSST: A Highly Modular Open Source Platform for Continuous Variable Quantum Key Distribution Applications

Sun, 23 Jun 2024 00:00:00 +0000

We present a highly modular Open Source Software to perform CV-QKD experiments. The software is hardware agnostic and was benchmarked on bulk and integrated receivers, reaching state of the art secret key rates.

QOSST: A Highly-Modular Open Source Platform for Experimental Continuous-Variable Quantum Key Distribution

Mon, 29 Apr 2024 00:00:00 +0000

Quantum Key Distribution (QKD) enables secret key exchange between two remote parties with information-theoretic security rooted in the laws of quantum physics. Encoding key information in continuous variables (CV), such as the values of quadrature components of coherent states of light, brings implementations much closer to standard optical communication systems, but this comes at the price of significant complexity in the digital signal processing techniques required for operation at low signal-to-noise ratios. In this work, we wish to lower the barriers to entry for CV-QKD experiments associated to this difficulty by providing a highly modular, open source software that is in principle hardware agnostic and can be used in multiple configurations. We benchmarked this software, called QOSST, using an experimental setup with a locally generated local oscillator, frequency multiplexed pilots and RF-heterodyne detection, and obtained state-of-the-art secret key rates of the order of Mbit/s over metropolitan distances at the asymptotic limit. We hope that QOSST can be used to stimulate further experimental advances in CV-QKD and be improved and extended by the community to achieve high performance in a wide variety of configurations.

Experimental Demonstration of Continuous-Variable Quantum Key Distribution with a Photonic Integrated Receiver and Modular Software

Wed, 22 Nov 2023 00:00:00 +0000

High-speed continuous-variable quantum key distribution with advanced digital signal processing

Sun, 02 Jul 2023 00:00:00 +0000

Continuous-variable quantum key distribution (CV-QKD) is a promising solution for providing high secure key rates in moderate loss channels. A great advantage with respect to discrete-variable (DV) systems is the use of a technology similar to the one used in classical coherent communication, in particular for the detection system, which can operate at room temperature and benefits from an easier integration process. In addition to this, the use of advanced digital signal processing (DSP) techniques developed for classical communication allows for bandwidth-efficient temporal shaping, which optimizes the performance of the CV-QKD system. These techniques applied to the detected signal are also fundamental for using a locally generated local oscillator, correcting frequency and phase differences using frequency-multiplexed pilots generated by the transmitter. In this presentation, we will describe how these DSP techniques can be applied to a CV-QKD system and show some recent experimental results obtained by our research group, including results for a receiver based on a Photonic Integrated Circuit (PIC).

CV-QKD Receiver Platform Based On A Silicon Photonic Integrated Circuit

Sun, 05 Mar 2023 00:00:00 +0000

We report on the characterization of a SiGe PIC-based receiver along with its usage in a Gaussian-modulated coherent state CV-QKD setup. Excess noise measurements lead to secret key rate estimations of 280 kbit/s at 6.9 km.

CV-QKD Receiver Platform Based On A Silicon Photonic Chip

Wed, 16 Nov 2022 00:00:00 +0000

A Versatile PIC-based CV-QKD receiver

Wed, 05 Oct 2022 00:00:00 +0000

A Versatile PIC-based CV-QKD Receiver

Mon, 29 Aug 2022 00:00:00 +0000

Experimental Demonstration of Discrete Modulation Formats for Continuous Variable Quantum Key Distribution

Sun, 24 Jul 2022 00:00:00 +0000

A Versatile CV-QKD system with a PIC-based receiver

Mon, 11 Jul 2022 00:00:00 +0000

2022 Roadmap on integrated quantum photonics

Mon, 31 Jan 2022 00:00:00 +0000

Abstract Integrated photonics will play a key role in quantum systems as they grow from few-qubit prototypes to tens of thousands of qubits. The underlying optical quantum technologies can only be realized through the integration of these components onto quantum photonic integrated circuits (QPICs) with accompanying electronics. In the last decade, remarkable advances in quantum photonic integration have enabled table-top experiments to be scaled down to prototype chips with improvements in efficiency, robustness, and key performance metrics. These advances have enabled integrated quantum photonic technologies combining up to 650 optical and electrical components onto a single chip that are capable of programmable quantum information processing, chip-to-chip networking, hybrid quantum system integration, and high-speed communications. In this roadmap article, we highlight the status, current and future challenges, and emerging technologies in several key research areas in integrated quantum photonics, including photonic platforms, quantum and classical light sources, quantum frequency conversion, integrated detectors, and applications in computing, communications, and sensing. With advances in materials, photonic design architectures, fabrication and integration processes, packaging, and testing and benchmarking, in the next decade we can expect a transition from single- and few-function prototypes to large-scale integration of multi-functional and reconfigurable devices that will have a transformative impact on quantum information science and engineering.

A versatile and high-performance PIC-based CV-QKD receiver

Wed, 03 Nov 2021 00:00:00 +0000

High-Rate Continuous Variable Quantum Key Distribution Based on Probabilistically Shaped 64 and 256-QAM

Mon, 13 Sep 2021 00:00:00 +0000

We designed a CV-QKD system with off-the-shelf components and established the feasibility of distributing 67.6 and 66.8 Mb/s secret key rates on average over a 9.5 km SMF link, using respectively probabilistically shaped 64 and 256 QAM, and relying on a novel analytical security proof.

Feasibility of satellite-to-ground continuous-variable quantum key distribution

Mon, 04 Jan 2021 00:00:00 +0000

Establishing secure communication links at a global scale is a major potential application of quantum information science but also extremely challenging for the underlying technology. While milestone experiments using satellite-to-ground links and exploiting singe-photon encoding for implementing quantum key distribution have shown recently that this goal is achievable, it is still necessary to further investigate practical solutions compatible with classical optical communication systems. Here we examine the feasibility of establishing secret keys in a satellite-to-ground downlink configuration using continuous-variable encoding, which can be implemented using standard telecommunication components certified for space environment and able to operate at high symbol rates. Considering a realistic channel model and state-of-the-art technology, and exploiting an orbit subdivision technique for mitigating fluctuations in the transmission efficiency, we find positive secret key rates for a low-Earth-orbit scenario, while finite-size effects can be a limiting factor for higher orbits. Our analysis determines regions of values for important experimental parameters where secret key exchange is possible and can be used as a guideline for experimental efforts in this direction.

Design and implementation of high-performance devices for continuous-variable quantum key distribution

Fri, 20 Dec 2019 00:00:00 +0000

Abstract :
Quantum key distribution (QKD) is one of the first quantum technologies that were able to provide commercially meaningful solutions to the problem of distributing cryptographic keys between trusted parties, guaranteeing long term security. It is now progressing towards technical maturity, by proposing multiple implementation alternatives. In this thesis, we study Continuous-Variables QKD (CV-QKD), which shares many common elements with classical coherent communication systems, and is a good candidate to facilitate the access to QKD for more users.The use of digital signal processing (DSP) techniques typical in classical communications has been only partially exploited in previous CV-QKD implementations. We experimentally implement standard telecommunication techniques like pulse shaping, adaptive filtering and mode recovery in order to improve the quantum secret key rate and optimize the occupied bandwidth.The potential of integration of the components in a photonic integrated circuit (PIC) is another important aspect of CV-QKD. We have tested a silicon photonics PIC integrating a 180º hybrid detector with two germanium photodiodes, showing that measured parameters are compatible with the generation of secret key.One of the most limiting factors of QKD is the performance under lossy channels, which is common in optical fibre for distances in the order of hundred kilometers. The range can be significantly extended using free space communications, and in particular satellites, where the losses at longer distances can be lower than those in fibre. We consider a model for a downlink satellite channel and predict the achievable secret key rates at different altitudes for CV-QKD, resulting in a potentially feasible technology for satellite communications, extending the range to intercontinental distances.

Design and implementation of high-performance devices for continuous-variable quantum key distribution

Fri, 20 Dec 2019 00:00:00 +0000

Quantum key distribution (QKD) is one of the first quantum technologies that were able to provide commercially meaningful solutions to the problem of distributing cryptographic keys between trusted parties, guaranteeing long term security. It is now progressing towards technical maturity, by proposing multiple implementation alternatives. In this thesis, we study Continuous-Variables QKD (CV-QKD), which shares many common elements with classical coherent communication systems, and is a good candidate to facilitate the access to QKD for more users.The use of digital signal processing (DSP) techniques typical in classical communications has been only partially exploited in previous CV-QKD implementations. We experimentally implement standard telecommunication techniques like pulse shaping, adaptive filtering and mode recovery in order to improve the quantum secret key rate and optimize the occupied bandwidth.The potential of integration of the components in a photonic integrated circuit (PIC) is another important aspect of CV-QKD. We have tested a silicon photonics PIC integrating a 180º hybrid detector with two germanium photodiodes, showing that measured parameters are compatible with the generation of secret key.One of the most limiting factors of QKD is the performance under lossy channels, which is common in optical fibre for distances in the order of hundred kilometers. The range can be significantly extended using free space communications, and in particular satellites, where the losses at longer distances can be lower than those in fibre. We consider a model for a downlink satellite channel and predict the achievable secret key rates at different altitudes for CV-QKD, resulting in a potentially feasible technology for satellite communications, extending the range to intercontinental distances.

Experimental investigation of practical unforgeable quantum money

Mon, 01 Jan 2018 00:00:00 +0000

Wiesner’s unforgeable quantum money scheme is widely celebrated as the first quantum information application. Based on the no-cloning property of quantum mechanics, this scheme allows for the creation of credit cards used in authenticated transactions offering security guarantees impossible to achieve by classical means. However, despite its central role in quantum cryptography, its experimental implementation has remained elusive because of the lack of quantum memories and of practical verification techniques. Here, we experimentally implement a quantum money protocol relying on classical verification that rigorously satises the security condition for unforgeability. Our system exploits polarization encoding of weak coherent states of light and operates under conditions that ensure compatibility with state-of-the-art quantum memories. We derive working regimes for our system using a security analysis taking into account all practical imperfections. Our results constitute a major step towards a real-world realization of this milestone protocol.