Nesta quarta-feira, dia 24 de Agosto de 2011, às 13:15hs, na Sala 03, Davi Dantas apresentará o trabalho intitulado

Low dimensional confinement structures on suspended liquid helium surfaces

D. S. Dantas, A. C. A. Ramos, A. Chaves, G. A. Farias, and F. M. Peeters

ABSTRACT: The system of electrons on the surface of liquid helium (EoH) is one of the most ideal objects for investigating the fundamental principles of the physics of low dimensionality,[1] since they do not have the inhomogeneities and impurities generally found on semiconductors.[2] Besides, these systems are expected to be useful for future technological applications: numerous physical systems have been proposed for constructing quantum computers, but formidable obstacles stand in the way of making even modest systems with a few hundred quantum bits(qubits).[3] On the other hand, EoH provides scalable electron traps and is a very attractive system for creating a scalable quantum computer.

Usually, the low-dimensional confinement structures in liquid Helium surfaces suggested in the literature are based on a planar surface, where the lateral confinement is induced by an external electrical potential controlled by electrodes.[4] In this work, we suggest an alternative way to produce lateral confinement in liquid helium surfaces, namely, we demonstrate that the shape of the surface can be designed to produce single and double quantum dots by adjusting the shape of the substrate. We propose a study about electrons on liquid helium surface, which is suspended on a substrate with a cavity. The surface was calculated for two cavities with different shapes, creating two different confinement systems. The first one has two cubic cavities connected by a channel, creating a coupled double-dot structure, whereas the other system has two channel-shaped cavities that intersect perpendicularly to each other, where a single dot is formed in the intersection. The electron is then deposited and confined to move on each surface by an external electric field. It was shown that the difference between energy levels can be tuned by varying the electric field and the bulk level, which are easily adjustably. The effect of an external magnetic field on the energy spectrum of these systems is also investigated.

[1] Marcos H. Degani and Oscar Hip´lito, Phys. Rev. B 32, 3300 (1985)
[2] A. C. A. Ramos et al., Phys. Rev. B 77, 045415 (2008)
[3] S. A. Lyon, Phys. Rev. A, 74, 052338 (2006)
[4] G. Papageorgiou et al., Appl. Phys. Lett. 86, 153106 (2005)