More Like this

1. Experimental Semi-quantum Key Distribution With Classical Users

   https://doi.org/10.22331/q-2022-09-22-819  

   Massa, Francesco ; Yadav, Preeti ; Moqanaki, Amir ; Krawec, Walter O. ; Mateus, Paulo ; Paunković, Nikola ; Souto, André ; Walther, Philip ( September 2022 , Quantum)

   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 

   more » « less
2. Mediated semi-quantum key distribution with improved efficiency

   https://doi.org/10.1088/2058-9565/ac7412  

   Guskind, Julia ; Krawec, Walter O ( June 2022 , Quantum Science and Technology)

   Abstract Mediated semi-quantum key distribution involves the use of two end-users who have very restricted, almost classical, capabilities, who wish to establish a shared secret key using the help of a fully-quantum server who may be adversarial. In this paper, we introduce a new mediated semi-quantum key distribution protocol, extending prior work, which has asymptotically perfect efficiency. Though this comes at the cost of decreased noise tolerance, our protocol is backwards compatible with prior work, so users may easily switch to the old (normally less efficient) protocol if the noise level is high enough to justify it. To prove security, we show an interesting reduction from the mediated semi-quantum scenario to a fully-quantum entanglement based protocol which may be useful when proving the security of other multi-user quantum key distribution protocols. 

   more » « less
3. Advances in quantum cryptography

   https://doi.org/10.1364/AOP.361502  

   Pirandola, S. ; Andersen, U_L ; Banchi, L. ; Berta, M. ; Bunandar, D. ; Colbeck, R. ; Englund, D. ; Gehring, T. ; Lupo, C. ; Ottaviani, C. ; et al ( December 2020 , Advances in Optics and Photonics)

   Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs are constantly improving, and experiments are gradually moving from proof-of-principle lab demonstrations to in-field implementations and technological prototypes. In this paper, we provide both a general introduction and a state-of-the-art description of the recent advances in the field, both theoretical and experimental. We start by reviewing protocols of quantum key distribution based on discrete variable systems. Next we consider aspects of device independence, satellite challenges, and protocols based on continuous-variable systems. We will then discuss the ultimate limits of point-to-point private communications and how quantum repeaters and networks may overcome these restrictions. Finally, we will discuss some aspects of quantum cryptography beyond standard quantum key distribution, including quantum random number generators and quantum digital signatures.

    

   more » « less
4. Quantum Cryptography for Enhanced Network Security: A Comprehensive Survey of Research, Developments, and Future Directions

   Akter, M ; Rodriguez-Cardenas, J ; Shahriar, H ; Cuzzocrea, A ; Wu, F ( December 2023 , IEEE Big Data 2023)

   With the ever-growing concern for internet security, the field of quantum cryptography emerges as a promising solution for enhancing the security of networking systems. In this paper, 20 notable papers from leading conferences and journals are reviewed and categorized based on their focus on various aspects of quantum cryptography, including key distribution, quantum bit commitment, post-quantum cryptography, and counterfactual quantum key distribution. The paper explores the motivations and challenges of employing quantum cryptography, addressing security and privacy concerns along with existing solutions. Secure key distribution, a critical component in ensuring the confidentiality and integrity of transmitted information over a network, is emphasized in the discussion. The survey examines the potential of quantum cryptography to enable secure key exchange between parties, even when faced with eavesdropping, and other applications of quantum cryptography. Additionally, the paper analyzes the methodologies, findings, and limitations of each reviewed study, pinpointing trends such as the increasing focus on practical implementation of quantum cryptography protocols and the growing interest in post-quantum cryptography research. Furthermore, the survey identifies challenges and open research questions, including the need for more efficient quantum repeater networks, improved security proofs for continuous variable quantum key distribution, and the development of quantum-resistant cryptographic algorithms, showing future directions for the field of quantum cryptography. 

   more » « less
5. Continuous entanglement distribution from an AlGaAs-on-insulator microcomb for quantum communications

   https://doi.org/10.1364/OPTICAQ.510032  

   Steiner, Trevor_J ; Shen, Maximilian ; Castro, Joshua_E ; Bowers, John_E ; Moody, Galan ( December 2023 , Optica Quantum)

   Using an aluminum gallium arsenide microring resonator, we demonstrate a bright quantum optical microcomb with >300 nm (>40 THz) bandwidth and more than 20 sets of time–energy entangled modes, enabling spectral demultiplexing with simple, off-the-shelf commercial telecom components. We report high-rate continuous entanglement distribution for two sets of entangled-photon pair frequency modes exhibiting up to 20 GHz/mW²pair generation rate. As an illustrative example of entanglement distribution, we perform a continuous-wave time-bin quantum key distribution protocol with 8 kbps sifted key rates while maintaining less than 10% error rate and sufficient two-photon visibility to ensure security of the channel. When the >20 frequency modes are multiplexed, we estimate >100 kbps entanglement-based key rates or the creation of a multi-user quantum communications network. The entire system requires less than 110 µW of on-chip optical power, demonstrating an efficient source of entangled frequency modes for quantum communications. As a proof of principle, a quantum key is distributed across 12 km of deployed fiber on the University of California Santa Barbara (UCSB) campus and used to encrypt a 21 kB image with <9% error.

    

   more » « less