Polaronic signature in the metallic phase of La0.7Ca0.3MnO3 films detected by scanning tunneling spectroscopy

In this work we map tunnel conductance curves with nanometric spatial resolution, tracking polaronic quasiparticle excitations when cooling across the insulator-to-metal transition in La0.7Ca0.3MnO3 films. In the insulating phase the spectral signature of polarons, a depletion of conductance at low bias flanked by peaks, is detected all over the scanned surface. These features are still observed at the transition and persist on cooling into the metallic phase. Polaron-binding energy maps reveal that polarons are not confined to regions embedded in a highly-conducting matrix but are present over the whole field of view both above and below the transition temperature.Comment: 10 pages, 4 figure

Quantum Information Processing with Ferroelectrically Coupled Quantum Dots

I describe a proposal to construct a quantum information processor using ferroelectrically coupled Ge/Si quantum dots. The spin of single electrons form the fundamental qubits. Small (<10 nm diameter) Ge quantum dots are optically excited to create spin polarized electrons in Si. The static polarization of an epitaxial ferroelectric thin film confines electrons laterally in the semiconductor; spin interactions between nearest neighbor electrons are mediated by the nonlinear process of optical rectification. Single qubit operations are achieved through "g-factor engineering" in the Ge/Si structures; spin-spin interactions occur through Heisenberg exchange, controlled by ferroelectric gates. A method for reading out the final state, while required for quantum computing, is not described; electronic approaches involving single electron transistors may prove fruitful in satisfying this requirement.Comment: 10 pages, 3 figure

Assessing the Capabilities of Sentinel-1 and 2 for Citywide Slum Mapping with Machine Learning

info:eu-repo/semantics/nonPublishe

Size-dependent light emission from mass-selected clusters.

The emission of photons in the visible wavelength range from mass-selected Ag+_n, Cu+_n, Pt+_n and Pd+_n ($n=1 \dots 5$) clusters is observed. Photons are detected ≈ 10-4 s after the cluster generation in a sputter source. The emission intensities display distinct variations with cluster size and material. The observations are interpreted in terms of the decay of metastable states which are excited during the high-energy sputtering process used for the generation of these clusters