80 research outputs found
DELight: a Direct search Experiment for Light dark matter with superfluid helium
To reach ultra-low detection thresholds necessary to probe unprecedentedly
low Dark Matter masses, target material alternatives and novel detector designs
are essential. One such target material is superfluid He which has the
potential to probe so far uncharted light Dark Matter parameter space at
sub-GeV masses. The new ``Direct search Experiment for Light dark matter'',
DELight, will be using superfluid helium as active target, instrumented with
magnetic micro-calorimeters. It is being designed to reach sensitivity to
masses well below 100\,MeV in Dark Matter-nucleus scattering interactions.Comment: IDM2022 proceedings submitted to SciPos
Can the wave function in configuration space be replaced by single-particle wave functions in physical space?
The ontology of Bohmian mechanics includes both the universal wave function
(living in 3N-dimensional configuration space) and particles (living in
ordinary 3-dimensional physical space). Proposals for understanding the
physical significance of the wave function in this theory have included the
idea of regarding it as a physically-real field in its 3N-dimensional space, as
well as the idea of regarding it as a law of nature. Here we introduce and
explore a third possibility in which the configuration space wave function is
simply eliminated -- replaced by a set of single-particle pilot-wave fields
living in ordinary physical space. Such a re-formulation of the Bohmian
pilot-wave theory can exactly reproduce the statistical predictions of ordinary
quantum theory. But this comes at the rather high ontological price of
introducing an infinite network of interacting potential fields (living in
3-dimensional space) which influence the particles' motion through the
pilot-wave fields. We thus introduce an alternative approach which aims at
achieving empirical adequacy (like that enjoyed by GRW type theories) with a
more modest ontological complexity, and provide some preliminary evidence for
optimism regarding the (once popular but prematurely-abandoned) program of
trying to replace the (philosophically puzzling) configuration space wave
function with a (totally unproblematic) set of fields in ordinary physical
space.Comment: 29 pages, 5 figures, to appear in Synthese Special Issue: Space-time
and the wave functio
Noise and charge discreteness as ultimate limit for the THz operation of ultra-small electronic devices
Altres ajuts: Consejería de Educación de la Junta de Castilla y León (project SA254P18)To manufacture faster electron devices, the industry has entered into the nanoscale dimensions and Terahertz (THz) working frequencies. The discrete nature of the few electrons present simultaneously in the active region of ultra-small devices generate unavoidable fluctuations of the current at THz frequencies. The consequences of this noise remain unnoticed in the scientific community because its accurate understanding requires dealing with consecutive multi-time quantum measurements. Here, a modeling of the quantum measurement of the current at THz frequencies is introduced in terms of quantum (Bohmian) trajectories. With this new understanding, we develop an analytic model for THz noise as a function of the electron transit time and the sampling integration time, which finally determine the maximum device working frequency for digital applications. The model is confirmed by either semi-classical or full- quantum time-dependent Monte Carlo simulations. All these results show that intrinsic THz noise increases unlimitedly when the volume of the active region decreases. All attempts to minimize the low signal-to-noise ratio of these ultra-small devices to get effective THz working frequencies are incompatible with the basic elements of the scaling strategy. One can develop THz electron devices, but they cannot have ultra-small dimensions. Or, one can fabricate ultra-small electron devices, but they cannot be used for THz working frequencies
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