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Bibliografie tematiche / Quantum ratchet

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Letteratura scientifica selezionata sul tema "Quantum ratchet"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 6 febbraio 2022

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Articoli di riviste sul tema "Quantum ratchet"

1

Linke, H. "Experimental Quantum Ratchets based on Solid State Nanostructures". Australian Journal of Physics 52, n. 5 (1999): 895. http://dx.doi.org/10.1071/ph99012.

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Ratchets are spatially asymmetric devices in which particles can move on average in one direction in the absence of external net forces or gradients. This is made possible by the rectification of fluctuations, which also provide the energy for the process. Interest in the physics of ratchets was revived in recent years when it emerged that the ratchet principle may be a suitable physical model for ‘molecular motors’, which are central to many fundamental biological processes, such as intracellular transport or muscle contraction. Most ratchets studied so far have relied on classical effects, but recently ‘quantum ratchets’, involving quantum effects, have also been studied. In the present article it is pointed out that semiconductor or metal nanostructures are very suitable systems for the realisation of experimental quantum ratchets. Recent experimental studies of a quantum ratchet based on an asymmetric quantum dot are reviewed.

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2

DANA, I., V. B. ROITBERG, V. RAMAREDDY, I. TALUKDAR e G. S. SUMMY. "QUANTUM-RESONANCE RATCHETS: THEORY AND EXPERIMENT". International Journal of Bifurcation and Chaos 20, n. 02 (febbraio 2010): 255–61. http://dx.doi.org/10.1142/s0218127410025697.

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A theory of quantum ratchets for a particle periodically kicked by a general periodic potential under quantum-resonance conditions is developed for arbitrary values of the conserved quasimomentum β. A special case of this theory is experimentally realized using a Bose–Einstein condensate (BEC) exposed to a pulsed standing light wave. While this case corresponds to completely symmetric potential and initial wave-packet, a purely quantum ratchet effect still arises from the generic noncoincidence of the symmetry centers of these two entities. The experimental results agree well with the theory after taking properly into account the finite quasimomentum width of the BEC. This width causes a suppression of the ratchet acceleration occurring for "resonant" β, so that the mean momentum saturates to a finite ratchet velocity, strongly pronounced relative to that for nonresonant β.

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3

Salger, Tobias, Sebastian Kling, Tim Hecking, Carsten Geckeler, Luis Morales-Molina e Martin Weitz. "Directed Transport of Atoms in a Hamiltonian Quantum Ratchet". Science 326, n. 5957 (26 novembre 2009): 1241–43. http://dx.doi.org/10.1126/science.1179546.

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Classical ratchet potentials, which alternate a driving potential with periodic random dissipative motion, can account for the operation of biological motors. We demonstrate the operation of a quantum ratchet, which differs from classical ratchets in that dissipative processes are absent within the observation time of the system (Hamiltonian regime). An atomic rubidium Bose-Einstein condensate is exposed to a sawtooth-like optical lattice potential, whose amplitude is periodically modulated in time. The ratchet transport arises from broken spatiotemporal symmetries of the driven potential, resulting in a desymmetrization of transporting eigenstates (Floquet states). The full quantum character of the ratchet transport was demonstrated by the measured atomic current oscillating around a nonzero stationary value at longer observation times, resonances occurring at positions determined by the photon recoil, and dependence of the transport current on the initial phase of the driving potential.

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4

Yukawa, Satoshi, Gen Tatara, Makoto Kikuchi e Hiroshi Matsukawa. "Quantum ratchet". Physica B: Condensed Matter 284-288 (luglio 2000): 1896–97. http://dx.doi.org/10.1016/s0921-4526(99)02982-8.

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5

Chen, Lei, Zhen-Yu Wang, Wu Hui, Cheng-Yu Chu, Ji-Min Chai, Jin Xiao, Yu Zhao e Jin-Xiang Ma. "Quantum ratchet effect in a time non-uniform double-kicked model". International Journal of Modern Physics B 31, n. 16-19 (26 luglio 2017): 1744063. http://dx.doi.org/10.1142/s0217979217440635.

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The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

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Ghosh, Pulak Kumar, e Deb Shankar Ray. "An underdamped quantum ratchet". Journal of Statistical Mechanics: Theory and Experiment 2007, n. 03 (2 marzo 2007): P03003. http://dx.doi.org/10.1088/1742-5468/2007/03/p03003.

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7

Long, Gui-Lu, e Tian-Cai Zhang. "Quantum ratchet with photons". Science Bulletin 60, n. 2 (gennaio 2015): 278. http://dx.doi.org/10.1007/s11434-014-0721-8.

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8

Chakraborty, Sagnik, Arpan Das, Arindam Mallick e C. M. Chandrashekar. "Quantum Ratchet in Disordered Quantum Walk". Annalen der Physik 529, n. 8 (4 luglio 2017): 1600346. http://dx.doi.org/10.1002/andp.201600346.

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9

Chen, Lei, Chao Xiong, Jin Xiao e Hong Chun Yuan. "Ratchet Effect in a Triple Delta-Kicked Model". Applied Mechanics and Materials 687-691 (novembre 2014): 692–95. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.692.

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We investigate the quantum ratchet effect in a triple delta-kicked model. Three symmetric flashing potentials alternately act on a particle with a symmetric and homogeneous initial state of zero momentum. Ratchet currents emerge when quantum resonances are excited. Ratchet currents in the triple model may be stronger than those in the previous model. Our work expands upon the quantum delta-kicked model and may contribute to experimental investigation of the quantum transport of cold atoms.

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Chen, Lei, Chao Xiong, Jin Xiao e Hong Chun Yuan. "Multi-Frequency Delta-Kicked Models for the Quantum Ratchet Effect". Advanced Materials Research 1049-1050 (ottobre 2014): 1431–35. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.1431.

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We investigate two multi-frequency delta-kicked models for the quantum ratchet effect, in which a flashing multi-frequency potential periodically acts on a particle. Ratchet currents emerge when quantum resonances are excited. Currents in multi-frequency models may be stronger than those in the previous two-frequency model. Our work expands upon the quantum delta-kicked model and may contribute to experimental investigation of the quantum transport of cold atoms.

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Più fonti

Tesi sul tema "Quantum ratchet"

1

Smirnov, Sergey. "Ratchet phenomena in quantum dissipative systems with spin-orbit interactions". kostenfrei, 2009. http://www.opus-bayern.de/uni-regensburg/volltexte/2009/1407/.

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2

Inkaya, Ugur Yigit. "Ratchet Effect In Mesoscopic Systems". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606929/index.pdf.

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Rectification phenomena in two specific mesoscopic systems are reviewed. The phenomenon is called ratchet effect, and such systems are called ratchets. In this thesis, particularly a rocked quantum-dot ratchet, and a tunneling ratchet are considered. The origin of the name is explained in a brief historical background. Due to rectification, there is a net non-vanishing electronic current, whose direction can be reversed by changing rocking amplitude, the Fermi energy, or applying magnetic field to the devices (for the rocked ratchet), and tuning the temperature (for the tunneling ratchet). In the last part, a theoretical examination based on the Landauer-Bü
ttiker formalism of mesoscopic quantum transport is presented.

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3

Faltermeier, Philipp [Verfasser], e Sergey D. [Akademischer Betreuer] Ganichev. "Terahertz Laser Induced Ratchet Effects and Magnetic Quantum Ratchet Effects in Semiconductor Nanostructures / Philipp Faltermeier ; Betreuer: Sergey D. Ganichev". Regensburg : Universitätsbibliothek Regensburg, 2017. http://d-nb.info/1148103945/34.

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4

Humphrey, Tammy Ellen Physics Faculty of Science UNSW. "Mesoscopic quantum ratchets and the thermodynamics of energy selective electron heat engines". Awarded by:University of New South Wales. Physics, 2003. http://handle.unsw.edu.au/1959.4/19186.

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A ratchet is an asymmetric, non-equilibrated system that can produce a directed current of particles without the need for macroscopic potential gradients. In rocked quantum electron ratchets, tunnelling and wave-reflection can induce reversals in the direction of the net current as a function of system parameters. An asymmetric quantum point contact in a GaAs/GaAlAs heterostructure has been studied experimentally as a realisation of a quantum electron ratchet. A Landauer model predicts reversals in the direction of the net current as a function of temperature, amplitude of the rocking voltage, and Fermi energy. Artifacts such as circuit-induced asymmetry, also known as self-gating, were carefully removed from the experimental data, which showed net current and net differential conductance reversals, as predicted by the model. The model also predicts the existence of a heat current where the net electron current changes sign, as equal numbers of high and low energy electrons are pumped in opposite directions. An idealised quantum electron ratchet is studied analytically as an energy selective electron heat engine and refrigerator. The hypothetical device considered consists of two electron reservoirs with different temperatures and Fermi energies. The reservoirs are linked via a resonant state in a quantum dot, which functions as an idealised energy filter for electrons. The efficiency of the device approaches the Carnot value when the energy transmitted by the filter is tuned to that where the Fermi distributions in the reservoirs are equal. The maximum power regime, where the filter transmits all electrons that contribute positively to the power, is also examined. Analytic expressions are obtained for the power and efficiency of the idealised device as both a heat engine and as a refrigerator in this regime of operation. The expressions depend on the ratio of the voltage to the difference in temperature of the reservoirs, and on the ratio of the reservoir temperatures. The energy selective electron heat engine is shown to be non-endoreversible, and to operate in an analogous manner to the three-level amplifier, a laser based quantum heat engine. Implications for improving the efficiency of thermionic refrigerators and power generators are discussed.

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Alvila, Markus. "A Performance Evaluation of Post-Quantum Cryptography in the Signal Protocol". Thesis, Linköpings universitet, Informationskodning, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-158244.

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The Signal protocol can be considered state-of-the-art when it comes to secure messaging, but advances in quantum computing stress the importance of finding post-quantum resistant alternatives to its asymmetric cryptographic primitives. The aim is to determine whether existing post-quantum cryptography can be used as a drop-in replacement for the public-key cryptography currently used in the Signal protocol and what the performance trade-offs may be. An implementation of the Signal protocol using commutative supersingular isogeny Diffie-Hellman (CSIDH) key exchange operations in place of elliptic-curve Diffie-Hellman (ECDH) is proposed. The benchmark results on a Samsung Galaxy Note 8 mobile device equipped with a 64-bit Samsung Exynos 9 (8895) octa-core CPU shows that it takes roughly 8 seconds to initialize a session using CSIDH-512 and over 40 seconds using CSIDH-1024, without platform specific optimization. To the best of our knowledge, the proposed implementation is the first post-quantum resistant Signal protocol implementation and the first evaluation of using CSIDH as a drop-in replacement for ECDH in a communication protocol.

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Mendes, Carlos Fábio de Oliveira. "Dissipação quântica em sistemas abertos finitos". Universidade Federal do Amazonas, 2014. http://tede.ufam.edu.br/handle/tede/4255.

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CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico
In this work we consider the dynamical aspect of open quantum systems where a particle is subject to energy exchange with the environment. The environment (bath) consists of a finite number N of harmonic oscillators (HOs), characterizing a structured bath, for which a non-Markovian behavior is expected. We determine the numerical solution of the stochastic Schrödinger equation for a particle coupled to the bath. We study two different situations for the system’s particle: the harmonic potential and the ratchet potential. In the limit N → ¥ the bath is assumed to have an ohmic, sub-ohmic, and super-ohmic spectral density. In the case of the harmonic potential, for low values of N we observe an energy exchange between system and bath indefinitely in time, while for intermediate values of N is observed a decay in two time regimes: exponential for short times and power law for larger times. In the case of the ratchet potential, we observe that the energy returns to the systemeven for intermediate values of N. Wave packets are used to determine the evolution of the particle in the system potential.
Neste trabalho consideramos o aspecto dinâmico de sistemas quânticos abertos onde uma partícula fica sujeita a trocas de energia com o ambiente. O ambiente (banho) é composto de um número finito N de osciladores harmônicos (HOs), caracterizando um banho estruturado, para o qual um comportamento não-Markoviano é esperado. Determinamos a solução numérica da equação de Schrödinger estocástica para uma partícula acoplada ao banho. Estudamos duas situações distintas para o sistema de partícula: o potencial harmônico e o potencial de catraca. No limite N → ¥ o banho é assumido ter um espectro de densidade ôhmico, sub-ôhmico e super-ôhmico. No caso do potencial harmônico, para baixos valores de N observamos uma troca de energia entre sistema e banho indefinidamente no tempo, enquanto que para valores intermediários de N observa-se decaimento em dois regimes de tempo: exponencial para baixos valores de tempo e lei de potência para valores mais altos de tempo. No caso do potencial de catraca, observamos que a energia volta para o sistema até para valores intermediários de N. Pacotes de ondas são usadas para determinar a evolução da partícula nos potenciais do sistema.

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7

Rapp, Anthony P. "Numerical simulations of cold atom ratchets in dissipative optical lattices". Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1565625897258688.

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8

Genske, Maximilian [Verfasser], Achim [Gutachter] Rosch e Sebastian [Gutachter] Diehl. "Periodically driven many-body quantum systems : Quantum Ratchets, Topological States and the Floquet-Boltzmann Equation / Maximilian Genske ; Gutachter: Achim Rosch, Sebastian Diehl". Köln : Universitäts- und Stadtbibliothek Köln, 2017. http://d-nb.info/114376692X/34.

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9

Hur, Gwang-Ok. "Chaotic Hamiltonian quantum ratchets and filters with cold atoms in optical lattices : properties of Floquet states". Thesis, University College London (University of London), 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430759.

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Smirnov, Sergey [Verfasser]. "Ratchet phenomena in quantum dissipative systems with spin orbit interactions / vorgelegt von Sergey Smirnov". 2009. http://d-nb.info/998562602/34.

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Capitoli di libri sul tema "Quantum ratchet"

1

Fornés, José Antonio. "Quantum Ratchets". In Principles of Brownian and Molecular Motors, 123–48. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-64957-9_8.

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2

Grifoni, Milena. "Quantum Dissipative Ratchets". In Nonlinear Dynamics of Nanosystems, 111–20. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2010. http://dx.doi.org/10.1002/9783527629374.ch3.

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3

Tanatar, B., E. Kececioglu e M. C. Yalabik. "Memory Effects in Stochastic Ratchets". In Quantum Mesoscopic Phenomena and Mesoscopic Devices in Microelectronics, 251–56. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-011-4327-1_16.

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4

Linke, H., e A. M. Song. "Electron Ratchets—Nonlinear Transport in Semiconductor Dot and Antidot Structures". In Electron Transport in Quantum Dots, 317–61. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4615-0437-5_8.

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Atti di convegni sul tema "Quantum ratchet"

1

Ganichev, S. D., S. A. Tarasenko, P. Olbrich, J. Karch, M. Hirmer, F. Muller, M. Gmitra et al. "Magnetic quantum ratchet effect in graphene". In 2013 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2013). IEEE, 2013. http://dx.doi.org/10.1109/irmmw-thz.2013.6665558.

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Denur, Jack. "Modified Feynman ratchet with velocity-dependent fluctuations". In QUANTUM LIMITS TO THE SECOND LAW: First International Conference on Quantum Limits to the Second Law. AIP, 2002. http://dx.doi.org/10.1063/1.1523825.

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Robichaud, Luc, e Jacob J. Krich. "InGaN quantum dot superlattices as ratchet band solar cells". In 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC). IEEE, 2021. http://dx.doi.org/10.1109/pvsc43889.2021.9518410.

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4

Salger, T., S. Kling, T. Hecking e M. Weitz. "Directed transport of ultracold atoms in a Hamiltonian quantum ratchet". In 11th European Quantum Electronics Conference (CLEO/EQEC). IEEE, 2009. http://dx.doi.org/10.1109/cleoe-eqec.2009.5192464.

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Golub, L. E., A. V. Nalitov, E. L. Ivchenko, P. Olbrich, J. Kamann, J. Eroms, D. Weiss e S. D. Ganichev. "Ratchet effects in graphene and quantum wells with lateral superlattice". In THE PHYSICS OF SEMICONDUCTORS: Proceedings of the 31st International Conference on the Physics of Semiconductors (ICPS) 2012. AIP, 2013. http://dx.doi.org/10.1063/1.4848314.

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Pusch, Andreas, Nicholas P. Hylton e Nicholas J. Ekins-Daukes. "Comparison of possible realizations of quantum ratchet intermediate band solar cells". In 2018 IEEE 7th World Conference on Photovoltaic Energy Conversion (WCPEC) (A Joint Conference of 45th IEEE PVSC, 28th PVSEC & 34th EU PVSEC). IEEE, 2018. http://dx.doi.org/10.1109/pvsc.2018.8547321.

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Preda, C. E., B. Segard e P. Glorieux. "Asymmetric modulation of a laser as a weak optical ratchet". In 2007 European Conference on Lasers and Electro-Optics and the International Quantum Electronics Conference. IEEE, 2007. http://dx.doi.org/10.1109/cleoe-iqec.2007.4386955.

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Tamaki, Ryo, Yasushi Shoji e Yoshitaka Okada. "Type-II Quantum Dots for Application to Photon Ratchet Intermediate Band Solar Cells". In 2017 IEEE 44th Photovoltaic Specialists Conference (PVSC). IEEE, 2017. http://dx.doi.org/10.1109/pvsc.2017.8366722.

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Ang, Yee Sin, Zhongshui Ma e Chao Zhang. "The quantum ratchet effect in two dimensional semiconductors for detection of terahertz radiation". In 2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). IEEE, 2016. http://dx.doi.org/10.1109/irmmw-thz.2016.7758768.

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Reimann, Peter, Milena Grifoni e Peter Hänggi. "Adiabatically rocked quantum ratchets". In Applied nonlinear dynamics and stochastic systems near the millenium. AIP, 1997. http://dx.doi.org/10.1063/1.54183.

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