Seminars

D.L.Shepelyansky
Deterministic ratchets in asymmetric nanostructures

Location: Fachbereich Physik, SR E3
Time: Thursday 12.07.2007, 14h c.t.

A board of rigid disks on a triangular lattice has been invented by Galton in 1889 to demonstrate the appearance of statistical laws from dynamical motion. This system, also called periodic Lorentz gas, has been proved to be completely chaotic by Sinai in 60th. The dynamics remains chaotic also for semidisks scatterers oriented in one direction. In this case the inversion symmetry is broken but the directed transport remains forbidden by the detailed balance principle. This remains true also in presence of polarized monochromatic force produced by microwave radiation. However, when dissipation is present, a new stationary state is born from chaos as shown in [1]. It is characterized by a directed transport which can be efficiently controlled by the microwave polarization even if mean force is zero. Being universal this effect exists for Maxwell or Fermi-Dirac thermostatted gas moving between semi-disks in presence of a microwave field [2-5]. Nowadays technology allows to realize the semidisk Galton board with a two-dimensional electron gas in a superlattice of micron size antidots. In this case the theory predicts appearance of strong currents induced by microwave fields. This opens new possibilities for creation of room temperature detectors of terahertz radiation. Combined effects of magnetic and microwave fields will be also discussed. (*) http://www.quantware.ups-tlse.fr/dima/
[1] A.D.Chepelianskii and D.L.Shepelyansky, Phys. Rev. B, 71, 052508 (2005).
[2] G.Cristadoro and D.L.Shepelyansky, Phys. Rev. E 71, 036111 (2005).
[3] A.D.Chepelianskii, Eur. Phys. J. B, 52, 389 (2006).
[4] M.V.Entin and L.I.Magarill, Phys. Rev. B 72, 205206 (2006).
[5] A.D.Chepelianskii, M.V.Entin, L.I.Magarill and D.L.Shepelyansky, Eur. Phys. J. B v.56, p.323-333 (2007).

 

More information: F. von Oppen (vonoppenphysik.fu-berlin.de)

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