Verena Yacoub | LIP6 - Équipe QI

Verena Yacoub

Wed, 12 Nov 2025 00:00:00 +0000

Photonics experiments aimed to study the quantum advantage in different communication and computation tasks.

Violating Bell inequalities using photon path encoding

Wed, 12 Nov 2025 00:00:00 +0000

In this work we investigate the use of photon path entanglement for the violation of a Bell inequality. The advantage of this encoding is that Bell pairs can be distributed with a rate scaling as the square root of the transmitivity of the channel in an heralding protocol, instead of a linear scaling in e.g. polarisation-based schemes. The drawback is that it is hard to implement generic Pauli measurements. We explore different ways to implement tackle this issue.

Toward quantum advantage with photonic state injection

Fri, 11 Jul 2025 00:00:00 +0000

We propose a new scheme for near-term photonic quantum devices that allows us to increase the expressive power of the quantum models beyond what linear optics can do. This scheme relies upon state injection, a measurement-based technique that can produce states that are more controllable, and solve learning tasks that are believed to be intractable classically. We explain how circuits made of linear optical architectures separated by state injections are well-suited for experimental implementation. In addition, we give theoretical results regarding the evolution of the purity of the resulting states, and we discuss how it impacts the distinguishability of the circuit outputs. Finally, we study a computational subroutine of learning algorithms named probability estimation, and we show that the state injection scheme we propose may offer a potential quantum advantage in a regime that can be more easily achieved than state-of-the-art adaptive techniques. Our analysis offers new possibilities for near-term advantage that rely on overcoming fewer experimental difficulties.

Experimentally Certified Transmission of a Quantum Message through an Untrusted and Lossy Quantum Channel via Bell's Theorem

Wed, 01 Jan 2025 00:00:00 +0000

Quantum transmission links are central elements in essentially all protocols involving the exchange of quantum messages. Emerging progress in quantum technologies involving such links needs to be accompanied by appropriate certification tools. In adversarial scenarios, a certification method can be vulnerable to attacks if too much trust is placed on the underlying system. Here, we propose a protocol in a device-independent framework, which allows for the certification of practical quantum transmission links in scenarios in which minimal assumptions are made about the functioning of the certification setup. In particular, we take unavoidable transmission losses into account by modeling the link as a completely positive trace-decreasing map. We also, crucially, remove the assumption of independent identically distributed samples, which is known to be incompatible with adversarial settings. Particular emphasis is put on a one-sided device-independent scenario, in which the sender possesses trusted resources. Finally, in view of the use of the certified transmitted states for follow-up applications, our protocol moves beyond certification of the channel to allow us to estimate the quality of the transmitted quantum message itself. To illustrate the practical relevance and the feasibility of our protocol with currently available technology, we provide an experimental implementation in the one-sided device-independent setting, based on a state-of-the-art polarization-entangled photon-pair source in a Sagnac configuration, and analyze its robustness for realistic losses and errors.

Experimental Demonstration of Quantum Advantage for Computing and Communication Tasks

Wed, 18 Dec 2024 00:00:00 +0000

Félicitations Dr.Yacoub !

Abstract

Les caractéristiques distinctives et souvent contre-intuitives de la mécanique quantique, telles que la superposition, l’absence de clonage et l’intrication, ont ouvert de nouvelles voies dans le domaine des sciences de l’information. Les chercheurs ont utilisé ces caractéristiques pour trouver des solutions efficaces à des problèmes de calcul difficiles et pour établir de nouveaux concepts de sécurité inviolables dans diverses tâches de communication. Cette thèse couvre un large éventail de sujets. Nous commençons par démontrer expérimentalement la quantité réduite de transfert d’informations nécessaire pour résoudre un problème spécifique. Ensuite, nous mettons en œuvre une technique cryptographique pour le jeu de pile ou face, en soulignant l’amélioration de la sensibilité à la tricherie offerte par le cadre quantique. En outre, dans le domaine de la cryptographie, nous avons étudié les moyens de rendre plus réalisable dans la pratique une fonctionnalité essentielle connue sous le nom de transfert oblivieux, qui s’appuie sur les ressources quantiques pour la sécurité du calcul. Ensuite, nous nous concentrons sur le problème de l’échantillonnage du boson, qui s’est avéré extrêmement difficile à l’aide de simulations classiques mais réalisable grâce à l’optique quantique ; nous avons cherché à mettre en œuvre un protocole de vérification pour cette tâche bien connue. Le système physique quantique qui sous-tend nos projets ultérieurs est entièrement basé sur l’optique quantique. Enfin, sur un plan plus théorique, nous avons cherché à approfondir le domaine des corrélations quantiques en développant des outils numériques pour caractériser la direction quantique au sein d’un réseau donné. Nos résultats fournissent des exemples concrets où un avantage quantique peut être démontré en pratique et ainsi ouvrir la voie vers de scénarios plus complexes en information quantique.

Towards quantum advantage with photonic state injection

Sun, 24 Nov 2024 00:00:00 +0000

We propose a new scheme for near-term photonic quantum device that allows to increase the expressive power of the quantum models beyond what linear optics can do. This scheme relies upon state injection, a measurement-based technique that can produce states that are more controllable, and solve learning tasks that are not believed to be tackled classically. We explain how circuits made of linear optical architectures separated by state injections are keen for experimental implementation. In addition, we give theoretical results on the evolution of the purity of the resulting states, and we discuss how it impacts the distinguishability of the circuit outputs. Finally, we study a computational subroutines of learning algorithms named probability estimation, and we show the state injection scheme we propose may offer a potential quantum advantage in a regime that can be more easily achieved that state-of-the-art adaptive techniques. Our analysis offers new possibilities for near-term advantage that require to tackle fewer experimental difficulties.

Towards an Experimental Implementation of Efficient Verification of Boson Sampling

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

A Practical Protocol for Quantum Oblivious Transfer from One-Way Functions

Mon, 17 Jun 2024 00:00:00 +0000

We present a new simulation-secure quantum oblivious transfer (QOT) protocol based on one-way functions in the plain model. With a focus on practical implementation, our protocol surpasses prior works in efficiency, promising feasible experimental realization. We address potential experimental errors and their correction, offering analytical expressions to facilitate the analysis of the required quantum resources. Technically, we achieve simulation security for QOT through an equivocal and relaxed-extractable quantum bit commitment.

Experimental cheat-sensitive quantum weak coin flipping

Fri, 01 Dec 2023 00:00:00 +0000

As in modern communication networks, the security of quantum networks will rely on complex cryptographic tasks that are based on a handful of fundamental primitives. Weak coin flipping (WCF) is a significant such primitive which allows two mistrustful parties to agree on a random bit while they favor opposite outcomes. Remarkably, perfect information-theoretic security can be achieved in principle for quantum WCF. Here, we overcome conceptual and practical issues that have prevented the experimental demonstration of this primitive to date, and demonstrate how quantum resources can provide cheat sensitivity, whereby each party can detect a cheating opponent, and an honest party is never sanctioned. Such a property is not known to be classically achievable with information-theoretic security. Our experiment implements a refined, loss-tolerant version of a recently proposed theoretical protocol and exploits heralded single photons generated by spontaneous parametric down conversion, a carefully optimized linear optical interferometer including beam splitters with variable reflectivities and a fast optical switch for the verification step. High values of our protocol benchmarks are maintained for attenuation corresponding to several kilometers of telecom optical fiber.

Experimental cheat-sensitive quantum weak coin flipping

Fri, 01 Dec 2023 00:00:00 +0000

Experimental Certification of Quantum Transmission via Bell's Theorem

Sat, 25 Nov 2023 00:00:00 +0000

Quantum transmission links are central elements in essentially all implementations of quantum information protocols. Emerging progress in quantum technologies involving such links needs to be accompanied by appropriate certification tools. In adversarial scenarios, a certification method can be vulnerable to attacks if too much trust is placed on the underlying system. Here, we propose a protocol in a device independent framework, which allows for the certification of practical quantum transmission links in scenarios where minimal assumptions are made about the functioning of the certification setup. In particular, we take unavoidable transmission losses into account by modeling the link as a completely-positive trace-decreasing map. We also, crucially, remove the assumption of independent and identically distributed samples, which is known to be incompatible with adversarial settings. Finally, in view of the use of the certified transmitted states for follow-up applications, our protocol moves beyond certification of the channel to allow us to estimate the quality of the transmitted state itself. To illustrate the practical relevance and the feasibility of our protocol with currently available technology we provide an experimental implementation based on a state-of-the-art polarization entangled photon pair source in a Sagnac configuration and analyze its robustness for realistic losses and errors.

Experimental cheat-sensitive quantum weak coin flipping

Thu, 17 Nov 2022 00:00:00 +0000