Engineered swift equilibration of a Brownian particle

A fundamental and intrinsic property of any device or natural system is its relaxation time relax, which is the time it takes to return to equilibrium after the sudden change of a control parameter [1]. Reducing $tau$ relax , is frequently necessary, and is often obtained by a complex feedback process. To overcome the limitations of such an approach, alternative methods based on driving have been recently demonstrated [2, 3], for isolated quantum and classical systems [4--9]. Their extension to open systems in contact with a thermostat is a stumbling block for applications. Here, we design a protocol,named Engineered Swift Equilibration (ESE), that shortcuts time-consuming relaxations, and we apply it to a Brownian particle trapped in an optical potential whose properties can be controlled in time. We implement the process experimentally, showing that it allows the system to reach equilibrium times faster than the natural equilibration rate. We also estimate the increase of the dissipated energy needed to get such a time reduction. The method paves the way for applications in micro and nano devices, where the reduction of operation time represents as substantial a challenge as miniaturization [10]. The concepts of equilibrium and of transformations from an equilibrium state to another, are cornerstones of thermodynamics. A textbook illustration is provided by the expansion of a gas, starting at equilibrium and expanding to reach a new equilibrium in a larger vessel. This operation can be performed either very slowly by a piston, without dissipating energy into the environment, or alternatively quickly, letting the piston freely move to reach the new volume

Implementing social awareness into engineering curricula

The inclusion of competences related to social context in engineers’ education has been recommended by several organizations and authors. Among these abilities appears the development of reflective and behavioral skills or the awareness of public debate in engineering. In order to create an engineer profile with expanded social commitment, some criteria have been implemented by accreditation boards. In the proposed contribution, we will review these criteria and requirements, analyze how they contribute to the future engineering profile, how universities have approached the inclusion of the new contents in their syllabi and identify the difficulties that this may present in real practice. A reflective digression about the need of going beyond the ethics, the habitus of the engineering profession, the implicit values in education and the existing gap between engineers and society is also included. Finally the subject is illustrated with the description of engineering in Spain and the results of interviews with the presidents of professional engineering associationsPostprint (published version

Manipulating spin and charge in magnetic semiconductors usingsuperconducting vortices

The continuous need for miniaturization and increase in device speed exerts pressureon the electronics industry to explore new avenues of information processing. One possibility is to use the spin to store, manipulate and carry information. Indeed,spintronics may hold the promise of providing such a new paradigm. However, all spintronics applications are faced with formidable challenges in attempting to find fastand efficient ways to create, transport, detect, control and manipulate spin textures and currents. Here we show how most of these operations can be performed in arelatively simple manner in a hybrid system consisting of a superconducting (SC) film and a paramagnetic diluted magnetic semiconductor (DMS) quantum well (QW). Ourproposal is based on the observation that the inhomogeneous magnetic fields of the SC create local spin and charge textures in the DMS, leading to effects such as Blochoscillations, an unusual Quantum Hall Effect, etc. We exploit the recent progress in manipulating magnetic flux bundles (vortices) in superconductors and show howthese can create, manipulate and control the spin textures in DMS.Comment: 13 pages, 4 figure