El paisaje como obra de arte total. Dimitris Pikionis y el entorno de la acrópolis

En 2011 se cumplen sesenta años del inicio, en 1951, del proceso de proyecto y construcción de uno de los paisajes arquitectónicos y culturales más fascinantes del siglo XX, llevado a cabo por el arquitecto griego Dimitris Pikionis en el entorno de la Acrópolis de Atenas. Con la minuciosidad de un artesano, la visión de un artista y la condición proyectual de un arquitecto, Pikionis organizó un sistema en el que se superpone la memoria individual a la memoria universal del lugar. El resultado es un palimpsesto que atraviesa los siglos y se convierte en un paisaje del tiempo, en el que encontramos rastros que nos llevan desde la idea de un paisaje clásico hasta una concepción metafísica, marcado por los trazos vanguardistas de Klee o de Kandinsky, con aires orientales y una cierta condición mística que lo convierten en una obra de arte total

The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method

Using the formal analysis made by Bohm in his book, {\em "Quantum theory"}, Dover Publications Inc. New York (1979), to calculate approximately the phase time for a transmitted and the reflected wave packets through a potential barrier, we calculate the phase time for a semiconductor system formed by different mesoscopic layers. The transmitted and the reflected wave packets are analyzed and the applicability of this procedure, based on the stationary phase of a wave packet, is considered in different conditions. For the applicability of the stationary phase method an expression is obtained in the case of the transmitted wave depending only on the derivatives of the phase, up to third order. This condition indicates whether the parameters of the system allow to define the wave packet by its leading term. The case of a multiple barrier systems is shown as an illustration of the results. This formalism includes the use of the Transfer Matrix to describe the central stratum, whether it is formed by one layer (the single barrier case), or two barriers and an inner well (the DBRT system), but one can assume that this stratum can be comprise of any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph

Zeno and anti-Zeno polarization control of spin-ensembles by induced dephasing

We experimentally and theoretically demonstrate the purity (polarization) control of qubits entangled with multiple spins, using induced dephasing in nuclear magnetic resonance (NMR) setups to simulate repeated quantum measurements. We show that one may steer the qubit ensemble towards a quasi-equilibrium state of certain purity, by choosing suitable time intervals between dephasing operations. These results demonstrate that repeated dephasing at intervals associated with the anti-Zeno regime lead to ensemble purification, whereas those associated with the Zeno regime lead to ensemble mixing.Comment: Main Text: 5 pages, 2 figures. Sup. Inf.: 5pages, 1 figur