A5040330812- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum Mechanics and Applications
- Quantum optics and atomic interactions
- Optical Network Technologies
- Quantum and electron transport phenomena
- Advanced Photonic Communication Systems
- Molecular Communication and Nanonetworks
- graph theory and CDMA systems
- Laser-Matter Interactions and Applications
- Mechanical and Optical Resonators
- Optical Wireless Communication Technologies
- Neural Networks and Reservoir Computing
- Orbital Angular Momentum in Optics
- Diamond and Carbon-based Materials Research
- Photonic and Optical Devices
- Quantum Electrodynamics and Casimir Effect
- Mathematical and Computational Methods
- Low-power high-performance VLSI design
- Semiconductor Quantum Structures and Devices
- Quantum-Dot Cellular Automata
- Plasmonic and Surface Plasmon Research
- Coding theory and cryptography
- IoT and Edge/Fog Computing
- Drug-Induced Ocular Toxicity
University of Leeds
2016-2025
Iran University of Medical Sciences
2022
University of Waterloo
2008-2010
Massachusetts Institute of Technology
2002-2007
Sharif University of Technology
2002
ICT Research Institute
2002
Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs constantly improving, and experiments gradually moving from proof-of-principle lab demonstrations to in-field implementations technological prototypes. In this review, we provide both general introduction state of art description recent advances field, theoretically experimentally. We start by reviewing key distribution based...
Quantum communication is rapidly gaining popularity due to its high security and technological maturity. However, most implementations are limited just two communicating parties (users). networks aim connect a multitude of users. Here, we present fully connected quantum network on city-wide scale without active switching or trusted nodes. We demonstrate simultaneous secure connections between all 28 pairings eight Our novel topology easily scalable many users, allows traffic management...
Practical schemes for measurement-device-independent quantum key distribution using phase and path or time encoding are presented. In addition to immunity existing loopholes in detection systems, our setup employs simple decoding modules without relying on polarization maintenance optical switches. Moreover, by employing a modified sifting technique handle the dead-time limitations single-photon detectors, scheme can be run with only two detectors. With phase-postselection technique,...
The recent advances in quantum information processing, sensing and communications are surveyed with the objective of identifying associated knowledge gaps formulating a roadmap for their future evolution. Since operation systems is prone to deleterious effects decoherence, which manifests itself terms bit-flips, phase-flips or both, pivotal subject error mitigation reviewed both presence absence coding. state-of-the-art, evolution machine learning also discussed, followed by discourse on...
Measurement-device-independent quantum key distribution with a finite number of decoy states is analyzed under finite-data-size assumption. By accounting for statistical fluctuations in parameter estimation, we investigate vacuum+weak- and vacuum+two-weak-decoy-state protocols. In each case, find proper operation regimes, where the performance our system comparable to asymptotic case which size approach infinity. Our results show that practical implementations this scheme can be both secure...
The decoy-state scheme is the most widely implemented quantum-key-distribution protocol in practice. In order to account for finite-size key effects on achievable secret generation rate, a rigorous statistical fluctuation analysis required. Originally, heuristic Gaussian-approximation technique was used this purpose, which, despite its analytical convenience, not sufficiently rigorous. has recently been made by using Chernoff bound. There considerable gap, however, between key-rate bounds...
We investigate the consequences of space-time being curved on space-based quantum communication protocols. analyze tasks that require either exchange single photons in a certain entanglement distribution protocol or beams light continuous-variable key scheme. find gravity affects propagation photons, therefore adding additional noise to channel for transmission information. The effects could be measured with current technology.
The weak nonlinear Kerr interaction between single photons and intense laser fields has been recently proposed as a basis for distributed optics-based solutions to few-qubit applications in quantum communication computation. Here, we analyse the above by employing continuous-time multi-mode model input/output to/from medium. In contrast previous single-mode treatments of this problem, our analysis takes into account full temporal content free-field input beams well non-instantaneous response...
Atmospheric optical communication systems that use preamplifiers and diversity reception are addressed. The particular techniques investigated include aperture averaging, linear combining, adaptive optics. On-off keying binary pulse position modulation considered. effects of atmospheric turbulence, background light, source extinction ratio, amplified spontaneous emission, receiver thermal noise studied in the context a semiclassical photon-counting approach. Numerical results presented using...
Memory dephasing and its impact on the rate of entanglement generation in quantum repeaters is addressed. For systems that rely probabilistic schemes for distribution connection, we estimate maximum achievable per employed memory our optimized partial nesting protocol, when a large number memories are being used each node. The above scales polynomially with distance, $L$, if infinitely long coherence times available or employ fully fault-tolerant scheme. finite no protection, optimistically...
Single-photon sources (SPSs) are mainly characterized by the minimum value of their second-order coherence function, viz. ${g}^{(2)}$ function. A precise measurement may, however, require high time-resolution devices, in whose absence, only time-averaged measurements accessible. These measures, standing alone, do not carry sufficient information for proper characterization SPSs. Here, we develop a theory, corroborated an experiment, which allows us to scrutinize properties heralded SPSs that...
This paper addresses multi-user quantum key distribution networks, in which any two users can mutually exchange a secret without trusting other nodes. The same network also supports conventional classical communications by assigning different wavelength bands to and signals. Time code division multiple access (CDMA) techniques, within passive star network, are considered. In the case of CDMA, it turns out that optimal performance is achieved at unity weight. A listen-before-send protocol...
A protocol with the potential of beating existing distance records for conventional quantum key distribution (QKD) systems is proposed. It borrows ideas from repeaters by using memories in middle link, and that measurement-device-independent QKD, which only requires optical source equipment at user's end. For certain fast memories, our scheme allows a higher repetition rate than repeaters, thereby requiring lower coherence times. By accounting various sources nonideality, such as memory...
Optimal wavelength assignment in dense-wavelength-division-multiplexing (DWDM) systems that integrate both quantum and classical channels is studied. In such systems, weak key distribution (QKD) signals travel alongside intense on the same fiber, where former can be masked by background noise induced latter. Here, we investigate how optimal mitigate this problem. We consider different DWDM structures various sources of crosstalk propose several near-optimal methods maximize total secret rate...
It is known that quantum scissors, as non-deterministic amplifiers, can enhance the performance of Gaussian-modulated continuous-variable key distribution (CV-QKD) in noisy and long-distance regimes operation. Here, we extend this result to a non-Gaussian CV-QKD protocol with discrete modulation. We show that, by using proper setting, use scissors receiver such discrete-modulation protocols would allow us achieve positive secret rates at high loss excess noise operation, which have been...
We investigate the use of quantum scissors, as candidates for non-deterministic amplifiers, in continuous-variable key distribution. Such devices rely on single-photon sources their operation and such, they do not necessarily preserve Guassianity channel. Using exact analytical modeling system components, we bound secret generation rate a protocol that uses scissors. find that, certain non-zero values excess noise, such can reach longer distances than counterpart with no amplification. This...
Quantum technologies are increasingly recognized as groundbreaking advancements set to redefine the landscape of computing, communications, and sensing by leveraging quantum phenomena, like entanglement teleportation. offer an interesting advantages such unconditional security, large communications capacity, unparalleled computational speed, ultra-precise capabilities. However, their global deployment faces challenges related communication ranges geographical boundaries. Non-terrestrial...
Memory-assisted measurement-device-independent quantum key distribution (MA-MDI-QKD) has recently been proposed as a possible intermediate step towards the realization of repeaters. Despite its relaxing some requirements on memories, choice memory in relation to layout setup and protocol stark effect our ability beat existing no-memory systems. Here, we investigate suitability nitrogen vacancy (NV) centers, MA-MDI-QKD. We particularly show that moderate cavity enhancement is required for NV...
We propose and study the feasibility of wireless quantum key distribution (QKD) in indoor environments. Such systems are essential providing access to developing communications networks. find a practical regime operation, where, presence external light sources loss, secret keys can be exchanged. Our findings identify trade-off between acceptable amount background receiver field view, where latter affects ease QKD system. In particular, we show that, using proper setting, provide mobility for...
The architecture proposed by Duan, Lukin, Cirac, and Zoller (DLCZ) for long-distance quantum communication with atomic ensembles is analyzed. Its fidelity throughput in entanglement distribution, swapping, teleportation derived within a framework that accounts multiple excitations the as well loss asymmetries channel. DLCZ performance metrics are obtained compared to corresponding results trapped-atom has been team from Massachusetts Institute of Technology Northwestern University (MIT NU)....
The feasibility of trust-free long-haul quantum key distribution (QKD) is addressed. We combine measurement-device-independent QKD, as an access technology, with a repeater setup, at the core future communication networks. This will provide link none whose intermediary nodes need to be trusted, or, in our terminology, QKD link. As main figure merit, we calculate secret generation rate when particular probabilistic protocol use. assume users are equipped imperfect single photon sources, which...
Memory-assisted measurement-device-independent quantum key distribution (MA-MDI-QKD) is a promising scheme that aims to improve the rate-versus-distance behavior of QKD system by using state-of-the-art devices. It can be seen as bridge between current links repeater based networks. While, similar repeaters, MA-MDI-QKD relies on memory (QM) units, requirements for such QMs are less demanding than probabilistic repeaters. Here we present variant structure only single physical QM:...
We propose orthogonal frequency division multiplexing (OFDM), as a spectrally efficient technique, for quantum key distribution (QKD) at the core of trustednode networks. Two main schemes are proposed and analyzed in detail, considering system imperfections, specifically, time misalignment issues. It turns out that while multiple service providers can share network infrastructure using techniques, no gain total secret generation rate is obtained if one uses conventional all-optical passive...
Quantum key distribution (QKD) offers a reliable solution to communication problems that require long-term data security. For its widespread use, however, the rate and reach of QKD systems must be improved. Twin-field (TF) is step forward toward this direction, with early demonstrations suggesting it can beat current rate-versus-distance records. A recently introduced variant TF-QKD particularly suited for experimental implementation, has been shown offer higher than other variants in...