6 research outputs found
Noise in Spectral Fluctuations of Quantum Systems
The power law in the power spectrum characterizes the
fluctuating observables of many complex natural systems. Considering the energy
levels of a quantum system as a discrete time series where the energy plays the
role of time, the level fluctuations can be characterized by the power
spectrum. Using a family of quantum billiards, we analyze the order to chaos
transition in terms of this power spectrum. A power law is found
at all the transition stages, and it is shown that the exponent is
related to the chaotic component of the classical phase space of the quantum
system.Comment: 4 pages, 5 figures, accepted for publication in Phys. Rev. Let
Vortices and chirality of magnetostatic modes in quasi-2D ferrite disk particles
In this paper we show that the vortex states can be created not only in
magnetically soft "small" (with the dipolar and exchange energy competition)
cylindrical dots, but also in magnetically saturated "big" (when the exchange
is neglected) cylindrical dots. A property associated with a vortex structure
becomes evident from an analysis of confinement phenomena of magnetic
oscillations in a ferrite disk with a dominating role of magnetic-dipolar
(non-exchange-interaction) spectra. In this case the scalar
(magnetostatic-potential) wave functions may have a phase singularity in a
center of a dot. A non-zero azimuth component of the flow velocity demonstrates
the vortex structure. The vortices are guaranteed by the chiral edge states of
magnetic-dipolar modes in a quasi-2D ferrite disk
Topological-phase effects and path-dependent interference in microwave structures with magnetic-dipolar-mode ferrite particles
Different ways exist in optics to realize photons carrying nonzero orbital
angular momentum. Such photons with rotating wave fronts are called twisted
photons. In microwaves, twisted fields can be produced based on small ferrite
particles with magnetic-dipolar-mode (MDM) oscillations. Recent studies showed
strong localization of the electric and magnetic energies of microwave fields
by MDM ferrite disks. For electromagnetic waves irradiating MDM disks, these
small ferrite samples appear as singular subwavelength regions with time and
space symmetry breakings. The fields scattered by a MDM disk are characterized
by topologically distinctive power-flow vortices and helicity structures. In
this paper we analyze twisted states of microwave fields scattered by MDM
ferrite disks. We show that in a structure of the fields scattered by MDM
particles, one can clearly distinguish rotating topological-phase dislocations.
Specific long-distance topological properties of the fields are exhibited
clearly in the effects of path-dependent interference with two coupled MDM
particles. Such double-twisted scattering is characterized by topologically
originated split-resonance states. Our studies of topological-phase effects and
path-dependent interference in microwave structures with MDM ferrite particles
are based on numerical analysis and recently developed analytical models. We
present preliminary experimental results aimed to support basic statements of
our studies.Comment: Submitted to Phys. Rev.
Low-Energy Physics in Neutrino LArTPCs
International audienceIn this white paper, we outline some of the scientific opportunities and challenges related to detection and reconstruction of low-energy (less than 100 MeV) signatures in liquid argon time-projection chamber (LArTPC) detectors. Key takeaways are summarized as follows. 1) LArTPCs have unique sensitivity to a range of physics and astrophysics signatures via detection of event features at and below the few tens of MeV range. 2) Low-energy signatures are an integral part of GeV-scale accelerator neutrino interaction final states, and their reconstruction can enhance the oscillation physics sensitivities of LArTPC experiments. 3) BSM signals from accelerator and natural sources also generate diverse signatures in the low-energy range, and reconstruction of these signatures can increase the breadth of BSM scenarios accessible in LArTPC-based searches. 4) Neutrino interaction cross sections and other nuclear physics processes in argon relevant to sub-hundred-MeV LArTPC signatures are poorly understood. Improved theory and experimental measurements are needed. Pion decay-at-rest sources and charged particle and neutron test beams are ideal facilities for experimentally improving this understanding. 5) There are specific calibration needs in the low-energy range, as well as specific needs for control and understanding of radiological and cosmogenic backgrounds. 6) Novel ideas for future LArTPC technology that enhance low-energy capabilities should be explored. These include novel charge enhancement and readout systems, enhanced photon detection, low radioactivity argon, and xenon doping. 7) Low-energy signatures, whether steady-state or part of a supernova burst or larger GeV-scale event topology, have specific triggering, DAQ and reconstruction requirements that must be addressed outside the scope of conventional GeV-scale data collection and analysis pathways