Anna Pappa | LIP6 - Équipe QI

Anonymous and private parameter estimation in networks of quantum sensors

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

Anonymity and privacy are two key properties of modern communication networks. In quantum networks, distributed quantum sensing has emerged as a powerful use case, with applications to clock synchronisation, detecting gravitational effects and more. In this work, we develop a new protocol that, for the first time, combines the different cryptographic properties of anonymity and privacy for the task of distributed parameter estimation. That is, we present a protocol that allows a selected subset of network participants to anonymously collaborate in estimating the average of their private parameters. Crucially, this is achieved without disclosing either the individual parameter values or the identities of the participants, neither to each other nor to the broader network.

Tsirelson's bound and Landauer's principle in a single-system game

Sat, 01 Dec 2018 00:00:00 +0000

We introduce a simple single-system game inspired by the Clauser-Horne-Shimony-Holt (CHSH) game. For qubit systems subjected to unitary gates and projective measurements, we prove that any strategy in our game can be mapped to a strategy in the CHSH game, which implies that Tsirelson’s bound also holds in our setting. More generally, we show that the optimal success probability depends on the reversible or irreversible character of the gates, the quantum or classical nature of the system, and the system dimension. We analyze the bounds obtained in light of Landauer’s principle, showing the entropic costs of the erasure associated with the game. This demonstrates a connection between the reversibility in fundamental operations embodied by Landauer’s principle and Tsirelson’s bound that arises from the restricted physics of a unitarily evolving single-qubit system.

A Comprehensive Analysis of Quantum E-voting Protocols

Mon, 27 Aug 2018 00:00:00 +0000

Recent advances at Google, IBM, as well as a number of research groups indicate that quantum computers will soon be reality. Motivated by the ever more realistic threat quantum computers pose to existing classical cryptographic protocols, researchers have developed several schemes to resist “quantum attacks”. In particular, for electronic voting, several e-voting schemes relying on properties of quantum mechanics have been proposed. However, each of these proposals comes with a different and often not well-articulated corruption model, has different objectives, and is accompanied by security claims which are never formalized and are at best justified only against specific attacks. In this paper, we systematize and evaluate the security of suggested e-voting protocols based on quantum technology. We examine the claims of these works concerning privacy, correctness and verifiability, and if they are correctly attributed to the proposed protocols. In all non-trivial cases, we identified specific quantum attacks that violate these properties. We argue that the cause of these failures lies in the absence of formal security models and in a more general lack of reference to the existing cryptographic literature.

Information Theoretically Secure Hypothesis Test for Temporally Unstructured Quantum Computation (Extended Abstract)

Tue, 27 Feb 2018 00:00:00 +0000

Classical multiparty computation using quantum resources

Mon, 18 Dec 2017 00:00:00 +0000

In this work, we demonstrate a way to perform classical multiparty computing among parties with limited computational resources. Our method harnesses quantum resources to increase the computational power of the individual parties. We show how a set of clients restricted to linear classical processing are able to jointly compute a nonlinear multivariable function that lies beyond their individual capabilities. The clients are only allowed to perform classical xor gates and single-qubit gates on quantum states. We also examine the type of security that can be achieved in this limited setting. Finally, we provide a proof-of-concept implementation using photonic qubits that allows four clients to compute a specific example of a multiparty function, the pairwise AND.

Multiparty Delegated Quantum Computing

Sun, 30 Jul 2017 00:00:00 +0000