59 research outputs found
Cavity-mediated electron-photon superconductivity
We investigate electron paring in a two-dimensional electron system mediated
by vacuum fluctuations inside a nanoplasmonic terahertz cavity. We show that
the structured cavity vacuum can induce long-range attractive interactions
between current fluctuations which lead to pairing in generic materials with
critical temperatures in the low-Kelvin regime for realistic parameters. The
induced state is a pair density wave superconductor which can show a transition
from a fully gapped to a partially gapped phase - akin to the pseudogap phase
in high- superconductors. Our findings provide a promising tool for
engineering intrinsic electron interactions in two-dimensional materials.Comment: 11 page
Optical control of the current-voltage relation in stacked superconductors
We simulate the current-voltage relation of short layered superconductors,
which we model as stacks of capacitively coupled Josephson junctions. The
system is driven by external laser fields, in order to optically control the
voltage drop across the junction. We identify parameter regimes in which
supercurrents can be stabilised against thermally induced phase slips, thus
reducing the effective voltage across the superconductor. Furthermore, single
driven Josephson junctions are known to exhibit phase-locked states, where the
superconducting phase is locked to the driving field. We numerically observe
their persistence in the presence of thermal fluctuations and capacitive
coupling between adjacent Josephson junctions. Our results indicate how
macroscopic material properties can be manipulated by exploiting the large
optical nonlinearities of Josephson plasmons.Comment: 7 pages, 7 figure
Mott polaritons in cavity-coupled quantum materials
We show that strong electron-electron interactions in cavity-coupled quantum
materials can enable collectively enhanced light-matter interactions with
ultrastrong effective coupling strengths. As a paradigmatic example we consider
a Fermi-Hubbard model coupled to a single-mode cavity and find that resonant
electron-cavity interactions result in the formation of a quasi-continuum of
polariton branches. The vacuum Rabi splitting of the two outermost branches is
collectively enhanced and scales with , where
is the number of electronic sites, and the maximal achievable value for
is determined by the volume of the unit cell of the crystal.
We find that for existing quantum materials can by far exceed
the width of the first excited Hubbard band. This effect can be experimentally
observed via measurements of the optical conductivity and does not require
ultra-strong coupling on the single-electron level. Quantum correlations in the
electronic ground state as well as the microscopic nature of the light-matter
interaction enhance the collective light-matter interaction compared to an
ensemble of independent two-level atoms interacting with a cavity mode.Comment: 11 pages, 4 figures. arXiv admin note: text overlap with
arXiv:1806.0675
Terahertz field control of interlayer transport modes in cuprate superconductors
We theoretically show that terahertz pulses with controlled amplitude and
frequency can be used to switch between stable transport modes in layered
superconductors, modelled as stacks of Josephson junctions. We find pulse
shapes that deterministically switch the transport mode between
superconducting, resistive and solitonic states. We develop a simple model that
explains the switching mechanism as a destablization of the centre of mass
excitation of the Josephson phase, made possible by the highly non-linear
nature of the light-matter coupling
Coarse graining methods for spin net and spin foam models
We undertake first steps in making a class of discrete models of quantum
gravity, spin foams, accessible to a large scale analysis by numerical and
computational methods. In particular, we apply Migdal-Kadanoff and Tensor
Network Renormalization schemes to spin net and spin foam models based on
finite Abelian groups and introduce `cutoff models' to probe the fate of gauge
symmetries under various such approximated renormalization group flows. For the
Tensor Network Renormalization analysis, a new Gauss constraint preserving
algorithm is introduced to improve numerical stability and aid physical
interpretation. We also describe the fixed point structure and establish an
equivalence of certain models.Comment: 39 pages, 13 figures, 1 tabl
Meeting Report: Aging Research and Drug Discovery
Aging is the single largest risk factor for most chronic diseases, and thus possesses large socioeconomic interest to continuously aging societies. Consequently, the field of aging research is expanding alongside a growing focus from the industry and investors in aging research. This year's 8th Annual Aging Research and Drug Discovery ARDD) meeting was organized as a hybrid meeting from August 30th to September 3rd 2021 with more than 130 attendees participating on-site at the Ceremonial Hall at University of Copenhagen, Denmark, and 1800 engaging online. The conference comprised of presentations from 75 speakers focusing on new research in topics including mechanisms of aging and how these can be modulated as well as the use of AI and new standards of practices within aging research. This year, a longevity workshop was included to build stronger connections with the clinical community
Pain in the cancer patient : different pain characteristics CHANGE pharmacological treatment requirements
Peer reviewe
- …