Dark Bell states in tunnel-coupled spin qubits

We investigate the dynamical purification of maximally entangled electron states by transport through coupled quantum dots. Under resonant ac driving and coherent tunneling, even-parity Bell states perform Rabi oscillations that decouple from the environment, leading to a dark state. The two electrons remain spatially separated, one in each quantum dot. We propose configurations where this effect will prove as antiresonances in transport spectroscopy experiments.Comment: 5 pages, 4 figures + supplementary information. Published versio

Fourier transform analysis of irradiated Weiss oscillations

We present a theoretical approach to study the effect of microwave radiation on the magnetoresistance of a one-dimensional superlattice. In our proposal the magnetoresistance of a unidirectional spatial periodic potential (superlattice), is modulated by microwave radiation due to an interference effect between both, space and time-dependent potentials. The final magnetoresistance will mainly depend on the spatial period of the superlattice and the radiation frequency. %Then, by tuning either the spatial period of the superlattice or the radiation %frequency, the magnetoresistance can be strongly modified. We consider an approach to study these effects based on the fast Fourier transform of the obtained magnetorresistance profiles in function of the inverse of the magnetic field. Based on this theory we propose the design of a novel radiation sensor for the Terahertz band.} % We first study the FFT of the system for each potential individually. Then we study jointly the FFT of the system when the two types of potentials are simultaneously acting.Comment: 5 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:0808.237

A chiral Maxwell Demon

We investigate the role of chirality on the performance of a Maxwell demon implemented in a quantum Hall bar with a localized impurity. Within a stochastic thermodynamics description we investigate the ability of such a demon to drive a current against a bias. We show that the ability of the demon to perform is directly related to its ability to extract information from the system. The key features of the proposed Maxwell demon are the topological properties of the quantum Hall system. The asymmetry of the electronic interactions felt at the localized state when the magnetic field is reversed joined to the fact that we consider energy dependent (and asymmetric) tunneling barriers that connect such state with the Hall edge modes allow the demon to properly work.Comment: 5 pages, 5 figure