Fast tunnel rates in Si/SiGe one-electron single and double quantum dots

We report the fabrication and measurement of one-electron single and double quantum dots with fast tunnel rates in a Si/SiGe heterostructure. Achieving fast tunnel rates in few-electron dots can be challenging, in part due to the large electron effective mass in Si. Using charge sensing, we identify signatures of tunnel rates in and out of the dot that are fast or slow compared to the measurement rate. Such signatures provide a means to calibrate the absolute electron number and verify single electron occupation. Pulsed gate voltage measurements are used to validate the approach.Comment: 4 pages, double column, 3 figure

Single-shot measurement and tunnel-rate spectroscopy of a Si/SiGe few-electron quantum dot

We investigate the tunnel rates and energies of excited states of small numbers of electrons in a quantum dot fabricated in a Si/SiGe heterostructure. Tunnel rates for loading and unloading electrons are found to be strongly energy dependent, and they vary significantly between different excited states. We show that this phenomenon enables charge sensing measurements of the average electron occupation that are analogous to Coulomb diamonds. Excited-state energies can be read directly from the plot, and we develop a rate model that enables a quantitative understanding of the relative sizes of different electron tunnel rates.Comment: 9 page

Data-driven identification of situated meanings in corpus data using Latent Class Analysis

Identifying the meanings of grammatical elements in context is a major challenge for corpus-linguistic studies of grammatical variation. This study proposes a novel solution to this problem. I describe the situated meanings of grammatical elements as latent constructs, i.e., social concepts that cannot be observed directly but need to be inferred from the way that speakers behave. I use Latent Class Analysis (LCA) to create a data-driven typology of meanings for three modal periphrases in spoken Spanish and compare this typology to manual classification of the data in terms of modality. My findings show that (a) the situated meanings identified by the LCA do not directly correspond to the modal meanings that are commonly assumed to govern the variation between the three periphrases, and (b) the data-driven typology of meanings explains better the variation between these periphrases

French and Spanish wh-interrogatives with and without wh

This article describes the usage of partial interrogatives without wh such as And you went…? in French and Spanish, and analyses the variation between such in-situ-Ø and in-situ-wh-interrogatives such as And you went where? On the basis of an analysis of in-situ-Ø-interrogatives in a corpus of spoken French and Spanish, these interrogatives are described as a particularly efficient means of realizing an information request. Due to the fact that their use is bound to contexts in which the information request is highly expected by the hearer, they can be produced using a minimal syntactic format and simultaneously ensure that the addressee produces the desired response. In comparison, the use of in-situ-wh is less context-sensitive. The analysis also investigates the possibility of differences between French and Spanish as regards the productivity of these interrogatives. An acceptability study of these interrogatives finds no significant difference in terms of the productivity and acceptability of in-situ-Ø in French and Spanish, whereas in-situ-wh reaches a higher acceptability in French than in Spanish. I interpret these results as evidence for a description of in-situ-Ø as an ad-hoc interactional resource whose use does not depend on conventionalization processes, whereas information-requesting in-situ-wh has become conventional in French