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Quantum Stirring, Ratchets, And Pumping
A pump is an alternating current-driven device that generates a direct current (DC). In the simplest configuration a pump has two leads connected to two reservoirs. In such open geometry, the pump takes particles from one reservoir and emits them into the other. Accordingly, a current is produced even if the reservoirs have the same temperature and chemical potential. Stirring is the operation of inducing a circulating current with a non-vanishing DC component in a closed system. The simplest geometry is obtained by integrating a pump in a closed circuit. More generally one can consider any type of stirring mechanism such as moving a spoon in a cup of coffee. Main observations Pumping and stirring effects in quantum physics have counterparts in purely classical stochastic and dissipative processes. The studies of quantum pumpingM. Buttiker, H. Thomas and A Pretre, Z. Phys. B Condens. Mat. 94, 133 (1994). P. W. Brouwer, Phys. Rev. B 58, R10135 (1998).B. L. Altshuler, L. I. Gla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brownian Ratchet
In the philosophy of thermal and statistical physics, the Brownian ratchet or Feynman–Smoluchowski ratchet is an apparent perpetual motion machine of the second kind (converting thermal energy into mechanical work), first analysed in 1912 as a thought experiment by Polish physicist Marian Smoluchowski.M. von Smoluchowski (1912) Experimentell nachweisbare, der Ublichen Thermodynamik widersprechende Molekularphenomene, ''Phys. Zeitshur.'' 13, p.1069 cited i Freund, Jan (2000) Stochastic Processes in Physics, Chemistry, and Biology, Springer, p.59/ref> It was popularised by American Nobel laureate physicist Richard Feynman in a physics lecture at the California Institute of Technology on May 11, 1962, during his Messenger Lectures series The Character of Physical Law in Cornell University in 1964 and in his text ''The Feynman Lectures on Physics'' as an illustration of the laws of thermodynamics. The simple machine, consisting of a tiny paddle wheel and a ratchet, appears to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, quantum field theory, quantum technology, and quantum information science. Classical physics, the collection of theories that existed before the advent of quantum mechanics, describes many aspects of nature at an ordinary ( macroscopic) scale, but is not sufficient for describing them at small (atomic and subatomic) scales. Most theories in classical physics can be derived from quantum mechanics as an approximation valid at large (macroscopic) scale. Quantum mechanics differs from classical physics in that energy, momentum, angular momentum, and other quantities of a bound system are restricted to discrete values ( quantization); objects have characteristics of both particles and waves (wave–particle duality); and there are limit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pmp Cyc A3
PMP may refer to: Biology and chemistry * Plant-made pharmaceuticals or Pharming * ''p''-Methoxyphenyl, a protecting group for amines * Polymethylpentene, a type of plastic Medicine * Prescription monitoring program * Pseudomyxoma peritonei, a cancer Business * Denel PMP, company division * Project Management Professional, a certification Technology * NAT-PMP, NAT Port Mapping Protocol * Pic Micro Pascal, Pascal compiler for PICs * Point-to-multipoint communication, in telecommunications * Portable media player, for digital media Politics * Parliamentary Monarchist Party, Burundi * People's Monarchist Party (Italy) * People's Movement Party, Romania * Pwersa ng Masang Pilipino, Philippines Transport * Plumpton railway station, a railway station in Sussex, England Other uses * Perlman Music Program, Shelter Island, New York, US * PMP Floating Bridge, a Soviet mobile pontoon bridge * Pompano Beach Airpark, IATA and FAA codes * Proto-Malayo-Polynesian language Proto- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berry Phase
In classical and quantum mechanics, geometric phase is a phase difference acquired over the course of a cycle, when a system is subjected to cyclic adiabatic processes, which results from the geometrical properties of the parameter space of the Hamiltonian. The phenomenon was independently discovered by S. Pancharatnam (1956), in classical optics and by H. C. Longuet-Higgins (1958)See page 12 in molecular physics; it was generalized by Sir Michael Berry in (1984). It is also known as the Pancharatnam–Berry phase, Pancharatnam phase, or Berry phase. It can be seen in the conical intersection of potential energy surfaces and in the Aharonov–Bohm effect. Geometric phase around the conical intersection involving the ground electronic state of the C6H3F3+ molecular ion is discussed on pages 385–386 of the textbook by Bunker and Jensen. In the case of the Aharonov–Bohm effect, the adiabatic parameter is the magnetic field enclosed by two interference paths, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pmp Cyc A4
PMP may refer to: Biology and chemistry * Plant-made pharmaceuticals or Pharming * ''p''-Methoxyphenyl, a protecting group for amines * Polymethylpentene, a type of plastic Medicine * Prescription monitoring program * Pseudomyxoma peritonei, a cancer Business * Denel PMP, company division * Project Management Professional, a certification Technology * NAT-PMP, NAT Port Mapping Protocol * Pic Micro Pascal, Pascal compiler for PICs * Point-to-multipoint communication, in telecommunications * Portable media player, for digital media Politics * Parliamentary Monarchist Party, Burundi * People's Monarchist Party (Italy) * People's Movement Party, Romania * Pwersa ng Masang Pilipino, Philippines Transport * Plumpton railway station, a railway station in Sussex, England Other uses * Perlman Music Program, Shelter Island, New York, US * PMP Floating Bridge, a Soviet mobile pontoon bridge * Pompano Beach Airpark, IATA and FAA codes * Proto-Malayo-Polynesian language Proto- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Berry Curvature
In physics, Berry connection and Berry curvature are related concepts which can be viewed, respectively, as a local gauge potential and gauge field associated with the Berry phase or geometric phase. The concept was first introduced by S. Pancharatnam as geometric phase and later elaborately explained and popularized by Michael Berry in a paper published in 1984 emphasizing how geometric phases provide a powerful unifying concept in several branches of classical and quantum physics. Berry phase and cyclic adiabatic evolution In quantum mechanics, the Berry phase arises in a cyclic adiabatic evolution. The quantum adiabatic theorem applies to a system whose Hamiltonian H(\mathbf R) depends on a (vector) parameter \mathbf R that varies with time t. If the n'th eigenvalue \varepsilon_n(\mathbf R) remains non-degenerate everywhere along the path and the variation with time ''t'' is sufficiently slow, then a system initially in the normalized eigenstate , n(\mathbf R(0))\rangle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Onsager Reciprocal Relations
In thermodynamics, the Onsager reciprocal relations express the equality of certain ratios between flows and forces in thermodynamic systems out of equilibrium, but where a notion of local equilibrium exists. "Reciprocal relations" occur between different pairs of forces and flows in a variety of physical systems. For example, consider fluid systems described in terms of temperature, matter density, and pressure. In this class of systems, it is known that temperature differences lead to heat flows from the warmer to the colder parts of the system; similarly, pressure differences will lead to matter flow from high-pressure to low-pressure regions. What is remarkable is the observation that, when both pressure and temperature vary, temperature differences at constant pressure can cause matter flow (as in convection) and pressure differences at constant temperature can cause heat flow. Perhaps surprisingly, the heat flow per unit of pressure difference and the density (matter) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternating Current
Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans and electric lamps into a wall socket. A common source of DC power is a battery cell in a flashlight. The abbreviations ''AC'' and ''DC'' are often used to mean simply ''alternating'' and ''direct'', as when they modify '' current'' or ''voltage''. The usual waveform of alternating current in most electric power circuits is a sine wave, whose positive half-period corresponds with positive direction of the current and vice versa. In certain applications, like guitar amplifiers, different waveforms are used, such as triangular waves or square waves. Audio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adiabatic Quantum Motor
An adiabatic quantum motor is a mechanical device, typically nanometric, driven by a flux of quantum particles and able to perform cyclic motions. The adjective “adiabatic” in this context refers to the limit when the dynamics of the mechanical degrees of freedom is slow compared with the dwell time of the particles passing through the device. In this regime, it is commonly assumed that the mechanical degrees of freedom behave classically. This class of devices works essentially as quantum pumps operated in reverse. While in a quantum pump, the periodic movement of some parameters pumps quantum particles from one reservoir to another, in a quantum motor a DC current of particles induces the cyclic motion of the device. One key feature of these motors is that quantum interferences can be used to increase their efficiency by enhancing the reflection coefficient In physics and electrical engineering the reflection coefficient is a parameter that describes how much of a wave is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Scattering Approach To Quantum Pumping
''The'' () is a grammatical article in English, denoting persons or things that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with nouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a consonant sound, and as (homophone of the archaic p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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