87,042 research outputs found
Landauer formula without Landauer's assumptions
No full textThe Landauer formula for dissipationless conductance lies at the heart of modern electronic transport, yet it remains without a clear microscopic basis. We analyse the Landauer formula microscopically and give a straightforward quantum kinetic derivation for open systems. Some important experimental implications follow. These lie beyond the Landauer result as popularly received
Landauer Formula without Landauers Assumptions
No full textThe Landauer formula for dissipationless conductance lies at the heart of modern electronic transport, yet it remains without a clear microscopic basis. We analyse the Landauer formula microscopically and give a straightforward quantum kinetic derivatio
Quantum landauer erasure with a molecular nanomagnet
No full textThe erasure of a bit of information is an irreversible operation whose minimal entropy production of kB ln 2 is set by the Landauer limit1. This limit has been verified in a variety of classical systems, including particles in traps2,3 and nanomagnets4. Here, we extend it to the quantum realm by using a crystal of molecular nanomagnets as a quantum spin memory and showing that its erasure is still governed by the Landauer principle. In contrast to classical systems, maximal energy efficiency is achieved while preserving fast operation owing to its high-speed spin dynamics. The performance of our spin register in terms of energy-time cost is orders of magnitude better than existing memory devices to date. The result shows that thermodynamics sets a limit on the energy cost of certain quantum operations and illustrates a way to enhance classical computations by using a quantum system.Author correction: In the version of this Letter originally published, the key to the green and open circles in Fig. 4 was reversed; it should have shown that the green circles correspond to 'From χ versus T' and the open circles correspond to 'From χ versus H y '. This has now been corrected in all versions of the Letter. (Figure Presented). DOI: 10.1038/s41567-018-0140-xQN/van der Zant La
La Ginestra. Collana di Classici per un individualismo solidale
No full textLa collana La ginestra, ideata e diretta da F. Andolfi e I. Testa, ha preso avvio dal 2008 presso le edizioni Diabasis, ed è composta da edizioni introdotte criticamente di autori classici e contemporanei (Emerson, Schleiermacher, Leroux, Simmel, Landauer, Adorno, Heller, Bauman, Frankfurt, Dewey alcuni tra gli autori pubblicati e in corso di pubblicazione
Noise and Transport in Mesoscopics: Physics Beyond the Landauer-Buttiker Formalism
No full textThe standard physical model of contemporary mesoscopic noise and transport consists in a phenomenologically based approach, proposed originally by Landauer and since continued and amplified by Buttiker, Imry and others. Throughout all the years of its gestation and growth, it is surprising that the Landauer-Buttiker approach to mesoscopics has matured with scant attention to the conserving properties lying at its roots: that is, at the level of actual microscopic principles. We systematically apply the sum rules for the electron gas to clarify the issue of conservation within the standard model of mesoscopic conduction. Noise, as observed in quantum point contacts, provides the vital clue
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Implications of the Landauer limit for quantum logic
No full textThe design of any system of quantum logic must take into account the implications of the Landauer limit for logical bits. Useful computation implies a deterministic outcome, and so any system of quantum computation must produce a final deterministic outcome, which in a quantum computer requires a quantum decision that produces a deterministic qubit. All information is physical, and any bit of information can be considered to exist in a physicality represented as a decision between the two wells of a double well potential in which the energy barrier between the two wells must be greater than kT·ln2. Any proposed system of quantum computation that does not result in such a deterministic outcome can only be considered stochastically as a probability distribution (i.e. a wave function). An example of such determinism in a quantum logic system is theorized to exist in the DNA molecule, where the decoherence of quantum decision results in an enantiomeric shift in the deoxyribose moiety that is appropriate to the Landauer limit
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
On the relationship between the quantum Langevin model and the Landauer formula
No full textWe show that, in the weak coupling limit, the main formalism of the phenomenological quantum Langevin model for single electron tunneling in small tunnel junctions is derivable within the framework of the rigorous generalized Landauer formula. © 1994
Anarchism and cosmopolitanism
No full textUntil recently, the relationship between theories of international anarchy and anarchism has been ignored. Very recent work has started to bridge the gap between International Relations theory and the usefulness of anarchism and anarchist theory for the understanding of global politics. This article takes this discussion one step further by examining the relationship between classical anarchism (1860s–1940s), cosmopolitanism, post-anarchism and the global justice movement. It then investigates the linkages between the works of the 19th- and 20th-century anarchists, Rudolf Rocker and Gustav Landauer, and contemporary examinations of the linkages between cultural nationalism, cosmopolitanism and the classical and post-anarchist projects
- …
