arXiv subjects

Preeti Yadav

Publications and source records attributed to Preeti Yadav.

4 recordsLinked to original sources

arXiv2026

Daylight quantum keyless private communication for free-space links

Quantum key distribution (QKD) is the most established approach in quantum communication. However, long-distance free-space implementations, particularly satellite links, remain challenging, especially during the day due to daylight background noise. Quantum keyless private communication (QKPC) is a quantum communication protocol that enables information-theoretic security with simpler system requirements, improved robustness against noise, and without the need for secret key distribution. QKPC and QKD are complementary, with QKPC enabling free-space links where QKD is impractical, while QKD provides channel monitoring for applications that require eavesdropping detection. Here, we report a complete implementation of QKPC in a daylight free-space experiment over a 90 m rooftop link, using an experimentally simple setup. Our demonstration includes all stages of the protocol, from encoding and synchronization to message decoding, operates entirely without auxiliary classical synchronization channels, and is implemented offline through post-processing. This work demonstrates the feasibility of practical and scalable quantum communication over high-noise daylight links and highlights the potential of QKPC as a complementary solution to QKD for future ground-based and space-based communication systems.

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arXiv2022

Experimental Semi-quantum Key Distribution With Classical Users

Quantum key distribution, which allows two distant parties to share an unconditionally secure cryptographic key, promises to play an important role in the future of communication. For this reason such technique has attracted many theoretical and experimental efforts, thus becoming one of the most prominent quantum technologies of the last decades. The security of the key relies on quantum mechanics and therefore requires the users to be capable of performing quantum operations, such as state preparation or measurements in multiple bases. A natural question is whether and to what extent these requirements can be relaxed and the quantum capabilities of the users reduced. Here we demonstrate a novel quantum key distribution scheme, where users are fully classical. In our protocol, the quantum operations are performed by an untrusted third party acting as a server, which gives the users access to a superimposed single photon, and the key exchange is achieved via interaction-free measurements on the shared state. We also provide a full security proof of the protocol by computing the secret key rate in the realistic scenario of finite-resources, as well as practical experimental conditions of imperfect photon source and detectors. Our approach deepens the understanding of the fundamental principles underlying quantum key distribution and, at the same time, opens up new interesting possibilities for quantum cryptography networks

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arXiv2020

Generation and Distribution of Quantum Oblivious Keys for Secure Multiparty Computation

The oblivious transfer primitive is sufficient to implement secure multiparty computation. However, secure multiparty computation based only on classical cryptography is severely limited by the security and efficiency of the oblivious transfer implementation. We present a method to efficiently and securely generate and distribute oblivious keys by exchanging qubits and by performing commitments using classical hash functions. With the presented hybrid approach, quantum and classical, we obtain a practical and high-speed oblivious transfer protocol, secure even against quantum computer attacks. The oblivious distributed keys allow implementing a fast and secure oblivious transfer protocol, which can pave the way for the widespread of applications based on secure multiparty computation.

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arXiv2014

Two-step orthogonal-state-based protocol of quantum secure direct communication with the help of order-rearrangement technique

The Goldenberg-Vaidman (GV) protocol for quantum key distribution (QKD) uses orthogonal encoding states of a particle. Its security arises because operations accessible to Eve are insufficient to distinguish the two states encoding the secret bit. We propose a two-particle cryptographic protocol for quantum secure direct communication, wherein orthogonal states encode the secret, and security arises from restricting Eve from accessing any two-particle operations. However, there is a non-trivial difference between the two cases. While the encoding states are perfectly indistinguishable in GV, they are partially distinguishable in the bi-partite case, leading to a qualitatively different kind of information-vs-disturbance trade-off and also options for Eve in the two cases.

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