A5053069305- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Quantum Mechanics and Applications
- Semiconductor Quantum Structures and Devices
- Quantum and electron transport phenomena
- Optical Network Technologies
- Chaos-based Image/Signal Encryption
- Photonic and Optical Devices
- Error Correcting Code Techniques
- Advanced Wireless Communication Techniques
- Semiconductor Lasers and Optical Devices
- Quantum optics and atomic interactions
- Semiconductor materials and devices
- Advanced Photonic Communication Systems
- Matrix Theory and Algorithms
- Surface and Thin Film Phenomena
- Cooperative Communication and Network Coding
- Spectroscopy and Quantum Chemical Studies
- Advanced Wireless Communication Technologies
- Strong Light-Matter Interactions
- Quantum-Dot Cellular Automata
- Cellular Automata and Applications
- Ultra-Wideband Communications Technology
- Wireless Body Area Networks
- Neural Networks and Reservoir Computing
Austrian Institute of Technology
2014-2023
AustriaTech (Austria)
2023
Institute of Science and Technology Austria
2023
SIB Swiss Institute of Bioinformatics
2014
Wienerberger (Czechia)
2010
University of South Australia
2010
Seibersdorf Laboratories (Austria)
2005-2007
TU Wien
1999-2005
In this paper, we present the quantum key distribution (QKD) network designed and implemented by European project SEcure COmmunication based on Quantum Cryptography (SECOQC) (2004–2008), unifying efforts of 41 research industrial organizations. The paper summarizes SECOQC approach to QKD networks with a focus trusted repeater paradigm. It discusses architecture functionality prototype, which has been put into operation in Vienna 2008 publicly demonstrated framework conference held from...
Abstract Quantum key distribution (QKD) using weak coherent states and homodyne detection is a promising candidate for practical quantum‐cryptographic implementations due to its compatibility with existing telecom equipment high efficiencies. However, despite the actual simplicity of protocol, security analysis this method rather involved compared discrete‐variable QKD. This article reviews theoretical foundations continuous‐variable quantum (CV‐QKD) Gaussian modulation rederives essential...
Secret communication over public channels is one of the central pillars a modern information society. Using quantum key distribution this achieved without relying on hardness mathematical problems which might be compromised by improved algorithms or future computers. State-of-the-art requires composable security against coherent attacks for finite number distributed states as well robustness implementation side-channels. Here, we present an continuous-variable satisfying these requirements....
A quantum key distribution (QKD) system must fulfill the requirement of universal composability to ensure that any cryptographic application (using QKD system) is also secure. Furthermore, theoretical proof responsible for security analysis and generation should cater number $N$ distributed states being finite in practice. Continuous-variable (CV) based on coherent states, despite a suitable candidate integration telecom infrastructure, has so far been unable demonstrate as existing proofs...
Ultra-reliable wireless communication links require the utilization of all diversity sources a channel. Hadani et al. propose two dimensional discrete symplectic Fourier transform (DSFT) as orthogonal pre-coder for time-frequency modulation scheme. In this paper we explore general precoding (OP) and its performance in time- frequency-selective channels. We show that iterative parallel interference cancellation (PIC) channel estimation methods can be used detection OP. A scalar signal model...
We present a pilot-assisted coherent intradyne reception methodology for CV-QKD with true local oscillator. An optically phase-locked reference tone, prepared using carrier-suppressed optical single-sideband modulation, is multiplexed in polarisation and frequency to the 250 Mbaud quantum signal order provide frequency- phase matching between Our concept allows high symbol rates can be operated at an extremely low excess-noise level, as validated by experimental measurements.
Cascade is an information reconciliation protocol proposed in the context of secret key agreement quantum cryptography. This allows removing discrepancies two partially correlated sequences that belong to distant parties, connected through a public noiseless channel. It highly interactive, thus requiring large number channel communications between parties proceed and, although its efficiency not optimal, it has become de-facto standard for practical implementations distribution. The aim this...
A coherent transmission methodology for a continuous-variable quantum key distribution (CV-QKD) system based on quantum-heterodyne measurement through intradyne receiver is experimentally demonstrated in the framework of 5G mobile fronthaul links. Continuous optical carrier synchronization obtained training information, which multiplexing to signal as pilot tone both, frequency and polarization. Spectral tailoring by means suppression single-sideband modulation adopted simultaneously...
A numerical security proof technique is used to analyse the of continuous-variable quantum key distribution (CV-QKD) protocols with phase-shift keying modulation against collective attacks in asymptotic limit. We argue why it sufficient consider a maximum number eight signal states and different postselection strategies for four (QPSK) (8PSK) untrusted ideal trusted nonideal detectors. introduce \emph{cross-shaped} strategy, show that both cross-shaped radial angular clearly outperform...
Abstract Quantum communication has seen rapid progress towards practical large-scale networks, with quantum key distribution (QKD) spearheading this development. While fibre-based systems have been shown to be well suited for metropolitan scales, suitable fibre infrastructure may not always in place. Here, we make the case an entanglement-based free-space network as a and efficient alternative applications. We developed deployable QKD system demonstrated its use realistic scenarios. For...
Continuous-variable quantum key distribution utilizes an ensemble of coherent states light to distribute secret encryption keys between two parties. One the challenges is thereby requirement capacity approaching error correcting codes in low signal-to-noise (SNR) regime (SNR < 0 dB). Multilevel coding (MLC) combined with multistage decoding (MSD) can solve this challenge combination multi-edge-type low-density parity-check (MET-LDPC) which are ideal for code rates SNR due degree-one variable...
Tremendous progress in experimental quantum optics during the past decades enabled advent of technologies, one which is communication. Aimed at novel methods for more secure or efficient information transfer, communication has developed into an active field research and proceeds toward full-scale implementations industrialization. Continuous-variable multi-photon state preparation, manipulation, coherent detection, as well respective theoretical tools phase-space optics, offer possibility to...
It is demonstrated that standard concepts for optics like Fabry–Pérot resonances and antireflection coatings can be extended to ballistic electron transport in semiconductor superlattices. The transmission through a superlattice miniband increased by factor of 2.4 if two further barriers are added at both sides the structure. condition Bloch states finite periodic potentials derived experimental evidence their existence obtained experiments.
The detection of positive selection is widely used to study gene and genome evolution, but its application remains limited by the high computational cost existing implementations. We present a series optimizations for more efficient estimation likelihood function on large-scale phylogenetic problems. illustrate our approach using branch-site model codon evolution.We introduce novel optimization techniques that substantially outperform both CodeML from PAML package previously optimized...
CodeML (part of the PAML package) implements a maximum likelihood-based approach to detect positive selection on specific branch given phylogenetic tree. While is widely used, it very compute-intensive. We present SlimCodeML, an optimized version for branch-site model. Our performance analysis shows that SlimCodeML substantially outperforms (up 9.38 times faster), especially large-scale genomic analyses.
We report on a highly efficient information reconciliation protocol for the binary symmetric channel (BSC) with feedback, proposed to be used in context of secret-key agreement. This is variant so-called Cascade protocol. Simulations determine efficiencies, defined by ratio actual transmitted necessary amount information, approximately 1.025 frame length 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> bits and error rate typically 10...
Massive multiple-input multiple-output (MIMO) systems are of high interest for ultra-reliable low-latency communication (URLLC) links. They provide channel hardening, i.e. reduced variations, due to the large number transmit antennas which exploit spatial diversity by beam-forming. MIMO requires state information (CSI) on base station side. For time-varying vehicular channels CSI acquired during uplink phase will be outdated following downlink phase, leading hardening. We investigate a...
The integration of quantum communication functions often requires dedicated opto-electronic components that do not bode well with the technology roadmaps telecom systems. We investigate capability commercial coherent transceiver sub-systems to support random number generation next classical data transmission, and demonstrate how entropy source based on vacuum fluctuations can be potentially converted into a true generator for this purpose. discuss two possible implementations, building...
We report several use-case demonstrations for quantum key distribution in deployed fiber networks. The tests were carried out under real world conditions at the end-user premises using commercial QKD systems.
The coherent transmission function and the tunneling time of one-dimensional arbitrary finite periodic structures are adjusted without changing resonance energies therefore band positions. method is based on modifications single period which reflected in a similarity transformation corresponding transfer matrix. Applied to semiconductor superlattices strong tuneable increase average miniband obtained. maximum reached if built by double barrier resonant diode. fundamentally different behavior...