December 2012

Abstracts of the QSIT Lunch Seminar, December 6, 2012

Exorcising the Maxwell Demon: Understanding the Interplay Between Work and Entropy in Quantum Systems

Philippe Faist, Institute for Theoretical Physics, ETH Zurich

Maxwell's demon was proposed in the 19th century as a thought experiment that would violate the second law of thermodynamics by reducing the entropy of an isolated gas at no work cost. This paradox had to wait for a century to be resolved with the help of concepts from information theory. In this talk, I will introduce some ideas that lead to the exorcism of the Maxwell demon, in particular Landauer's principle, which states that the erasure of information must cost work. More recently, many developments have contributed to the understanding of the thermodynamics of quantum systems, and I will present some recent results on determining fundamental lower bounds on work costs of general quantum processes.

Electron Waiting Times in Mesoscopic Transport

Christian Flindt, Département de Physique Théorique, Université de Genève

Investigations of electrical noise and fluctuations in mesoscopic conductors have traditionally involved measurements of the shot noise and the full counting statistics of transferred charges. Recently, the distribution of waiting times between consecutive electrons has been proposed as a complementary and useful characterization of stochastic quantum transport [1-3]. In this talk, I provide an overview of our recent Geneva efforts to evaluate the electronic waiting time distributions (WTDs) for several types of quantum conductors. For driven single-electron emitters, the WTD provides us with a simple and intuitive picture of the charge transport [1]. For fully phase-coherent conductors, we have formulated a compact determinant formula based on scattering theory which predicts a crossover in the WTD for a quantum point contact from Wigner-Dyson statistics at full transmission to Poisson statistics close to pinch-off [2]. To describe transport through quantum dots we use the theory of open quantum systems, which allows us to investigate the influence of dephasing on the WTD of electrons propagating through a double quantum dot [3].

References:

[1] M. Albert, C. Flindt, and M. Büttiker, Phys. Rev. Lett. 107, 086805 (2011)
[2] M. Albert, G. Haack, C. Flindt, and M. Büttiker, Phys. Rev.
[3] K. H. Thomas and C. Flindt, arXiv:1211.4995 (2012)