The Experts below are selected from a list of 12009 Experts worldwide ranked by ideXlab platform
Piotr Zbigniew Wieczorek - One of the best experts on this subject based on the ideXlab platform.
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an fpga implementation of the resolve time based true random number generator with quality control
IEEE Transactions on Circuits and Systems, 2014Co-Authors: Piotr Zbigniew WieczorekAbstract:This article describes a novel concept of a true random generator (TRNG) which exploits random behavior from a nearly-metastable operation of groups of FPGA flip-flops in opposite to many deep-Metastability-based TRNGs. The proposed concept harvests random behavior from the resolve time, which occurs in a wider range of flip-flop's operation than the deep-Metastability. Application of the resolve time randomness, requires the use of specially designed arbiter blocks. Presented TRNG provides a high stability of statistical quality which usually varies with PVT in similar solutions. Moreover, the use of an adaptive feedback loop increases robustness of the device. The article also describes the design considerations related to the adjustment of a flip-flop operating point, randomness extraction, and circuit fitting strategy.
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Dual-Metastability Time-Competitive True Random Number Generator
IEEE Transactions on Circuits and Systems I: Regular Papers, 2014Co-Authors: Piotr Zbigniew Wieczorek, Krzysztof GołofitAbstract:The paper introduces a new concept of a true random number generator (TRNG). Most Metastability-based solutions operate on the uncertainty of a logical output state of a device (flip-flop, D-latch) aimed to be resolved from an exact metastable point. However, it has been shown that the metastable point of a bistable circuit (which is practically impossible to reach) does not guarantee absolute randomness or sufficient entropy. We propose the concept of a device in which the direct proximity of the metastable point is not mandatory. In our concept the transition times of two devices are compared. Such construction is less sensitive to the proximity of the metastable point, temperature fluctuations, and power supply instabilities. The paper briefly describes the Metastability phenomena in general and other known Metastability-based TRNG concepts. A new concept of a dual-Metastability time-competitive generator is presented, analyzed both numerically and theoretically, and verified based on the sample circuit's implementation. Empirical and statistical test results are presented.
Trevor Mudge - One of the best experts on this subject based on the ideXlab platform.
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True Random Number Generator With a Metastability-Based Quality Control
IEEE Journal of Solid-State Circuits, 2008Co-Authors: Carlos Tokunaga, David Blaauw, Trevor MudgeAbstract:We present a Metastability-based true random number generator that achieves high entropy and passes NIST randomness tests. The generator grades the probability of randomness regardless of the output bit value by measuring the metastable resolution time. The system determines the original random noise level at the time of Metastability and tunes itself to achieve a high probability of randomness. Dynamic control enables the system to respond to deterministic noise and a qualifier module grades the individual metastable events to produce a high-entropy random bit-stream. The grading module allows the user to trade off output bit-rate with the quality of the bit-stream. A fully integrated true random number generator was fabricated in a 0.13 mum bulk CMOS technology with an area of 0.145 mm2.
Srinivas Devadas - One of the best experts on this subject based on the ideXlab platform.
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fpga based true random number generation using circuit Metastability with adaptive feedback control
Cryptographic Hardware and Embedded Systems, 2011Co-Authors: Mehrdad Majzoobi, Farinaz Koushanfar, Srinivas DevadasAbstract:The paper presents a novel and efficient method to generate true random numbers on FPGAs by inducing Metastability in bi-stable circuit elements, e.g. flip-flops. Metastability is achieved by using precise programmable delay lines (PDL) that accurately equalize the signal arrival times to flip-flops. The PDLs are capable of adjusting signal propagation delays with resolutions higher than fractions of a pico second. In addition, a real time monitoring system is utilized to assure a high degree of randomness in the generated output bits, resilience against fluctuations in environmental conditions, as well as robustness against active adversarial attacks. The monitoring system employs a feedback loop that actively monitors the probability of output bits; as soon as any bias is observed in probabilities, it adjusts the delay through PDLs to return to the metastable operation region. Implementation on Xilinx Virtex 5 FPGAs and results of NIST randomness tests show the effectiveness of our approach.
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exploiting Metastability and thermal noise to build a re configurable hardware random number generator
Proceedings of SPIE the International Society for Optical Engineering, 2005Co-Authors: Daihyu Lim, Damith C Ranasinghe, Srinivas Devadas, Ehnam Jamali, Derek Abbo, Pete H ColeAbstract:While pseudo random number generators based on computational complexity are widely used for most of cryptographic applications and probabilistic simulations, the generation of true random numbers based on physical randomness is required to guarantee the advanced security of cryptographic systems. In this paper we present a method to exploit manufacturing variations, metastablity, and thermal noise in integrated circuits to generate random numbers. This Metastability based physical random number generator provides a compact and low-power solution which can be fabricated using standard IC manufacturing processes. Test-chips were fabricated in TSMC 0.18um process and experimental results show that the generated random bits pass standard randomness tests su ccessfully. The operation of the proposed scheme is robust against environmental changes since it can be re-calibrated to new environmental conditions such as temperature and power supply voltage.
Igor Lesanovsky - One of the best experts on this subject based on the ideXlab platform.
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theory of classical Metastability in open quantum systems
Physical Review Research, 2021Co-Authors: Katarzyna Macieszczak, Dominic Rose, Igor Lesanovsky, Juan P GarrahanAbstract:We present a general theory of classical Metastability in open quantum systems. Metastability is a consequence of a large separation in timescales in the dynamics, leading to the existence of a regime when states of the system appear stationary, before eventual relaxation toward a true stationary state at much larger times. In this work, we focus on the emergence of classical Metastability, i.e., when metastable states of an open quantum system with separation of timescales can be approximated as probabilistic mixtures of a finite number of states. We find that a number of classical features follow from this approximation, for the manifold of metastable states, long-time dynamics between them, and symmetries of the dynamics. Namely, those states are approximately disjoint and thus play the role of metastable phases, the relaxation toward the stationary state is approximated by a classical stochastic dynamics between them, and weak symmetries correspond to their permutations. Importantly, the classical dynamics is observed not only on average but also at the level of individual quantum trajectories: We show that time coarse-grained continuous measurement records can be viewed as noisy classical trajectories, while their statistics can be approximated by that of the classical dynamics. Among others, this explains how first-order dynamical phase transitions arise from Metastability. Finally, to verify the presence of classical Metastability in a given open quantum system, we develop an efficient numerical approach that delivers the set of metastable phases together with the effective classical dynamics. Since the proximity to a first-order dissipative phase transition manifests as Metastability, the theory and tools introduced in this work can be used to investigate such transitions---which occur in the large size limit---through the metastable behavior of many-body systems of moderate sizes accessible to numerics.
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theory of classical Metastability in open quantum systems
arXiv: Statistical Mechanics, 2020Co-Authors: Katarzyna Macieszczak, Dominic Rose, Igor Lesanovsky, Juan P GarrahanAbstract:We present a general theory of classical Metastability in open quantum systems. Metastability is a consequence of a large separation in timescales in the dynamics, leading to the existence of a regime when states of the system appear stationary, before eventual relaxation towards a true stationary state at much larger times. In this work, we focus on the emergence of classical Metastability, i.e., when metastable states of an open quantum system with separation of timescales can be approximated as probabilistic mixtures of a finite number of states. We find that a number of classical features follow from this approximation, for both the manifold of metastable states and long-time dynamics between them. Namely, those states are approximately disjoint and thus play the role of metastable phases, and the relaxation towards the stationary state is approximated by a classical stochastic dynamics between them. Importantly, the classical dynamics is observed not only on average, but also at the level of individual quantum trajectories: we show that time coarse-grained continuous measurement records can be viewed as noisy classical trajectories, while their statistics can be approximated by that of the classical dynamics. Among others, this explains how first-order dynamical phase transitions arise from Metastability. Finally, in order to verify the presence of classical Metastability in a given open quantum system, we develop an efficient numerical approach that delivers the set of metastable phases together with the effective classical dynamics. Since the proximity to a first-order dissipative phase transition manifests as Metastability, the theory and tools introduced in this work can be used to investigate such transitions - which occur in the large size limit - through the metastable behavior of many-body systems of moderate sizes accessible to numerics.
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discrete time crystals in the absence of manifest symmetries or disorder in open quantum systems
Physical Review Letters, 2019Co-Authors: F M Gambetta, Juan P Garrahan, Federico Carollo, Matteo Marcuzzi, Igor LesanovskyAbstract:We establish a link between Metastability and a discrete time-crystalline phase in a periodically driven open quantum system. The mechanism we highlight requires neither the system to display any microscopic symmetry nor the presence of disorder, but relies instead on the emergence of a metastable regime. We investigate this in detail in an open quantum spin system, which is a canonical model for the exploration of collective phenomena in strongly interacting dissipative Rydberg gases. Here, a semiclassical approach reveals the emergence of a robust discrete time-crystalline phase in the thermodynamic limit in which Metastability, dissipation, and interparticle interactions play a crucial role. We perform numerical simulations in order to investigate the dependence on the range of interactions, from all to all to short ranged, and the scaling with system size of the lifetime of the time crystal.
Dziarmaga Jacek - One of the best experts on this subject based on the ideXlab platform.
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Nonadiabatic dynamics across a first-order quantum phase transition : quantized bubble nucleation
'American Physical Society (APS)', 2021Co-Authors: Sinha Aritra, Chanda Titas, Dziarmaga JacekAbstract:Metastability is a quintessential feature of first-order quantum phase transitions, which is lost either by dynamical instability or by nucleating bubbles of a true vacuum through quantum tunneling. By considering a drive across the first-order quantum phase transition in the quantum Ising chain in the presence of both transverse and longitudinal fields, we reveal multiple regions in the parameter space where the initial metastable state loses its Metastability in successive stages. The mechanism responsible is found to be semidegenerate resonant tunnelings to states with specific bubble sizes. We show that such dynamics of quantized bubble nucleations can be understood in terms of Landau-Zener transitions, which provide quantitative predictions of nucleation probabilities for different bubble sizes
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Non-adiabatic dynamics across a first order quantum phase transition: Quantized bubble nucleation
'American Physical Society (APS)', 2021Co-Authors: Sinha Aritra, Chanda Titas, Dziarmaga JacekAbstract:Metastability is a quintessential feature of first order quantum phase transitions, which is lost either by dynamical instability or by nucleating bubbles of a true vacuum through quantum tunneling. By considering a drive across the first order quantum phase transition in the quantum Ising chain in the presence of both transverse and longitudinal fields, we reveal multiple regions in the parameter space where the initial metastable state loses its Metastability in successive stages. The mechanism responsible is found to be semi-degenerate resonant tunnelings to states with specific bubble sizes. We show that such dynamics of quantized bubble nucleations can be understood in terms of Landau-Zener transitions, which provide quantitative predictions of nucleation probabilities for different bubble sizes.Comment: 7+4 pages, 5+3 figures. Close to published versio
