5 research outputs found
Fano interference of the Higgs mode in cuprate high-Tc superconductors
Despite decades of search for the pairing boson in cuprate high-Tc
superconductors, its identity still remains debated to date. For this reason,
spectroscopic signatures of electron-boson interactions in cuprates have always
been a center of attention. For example, the kinks in the quasiparticle
dispersion observed by angle-resolved photoemission spectroscopy (ARPES)
studies have motivated a decade-long investigation of electron-phonon as well
as electron-paramagnon interactions in cuprates. On the other hand, the overlap
between the charge-order correlations and the pseudogap in the cuprate phase
diagram has also generated discussions about the potential link between them.
In the present study, we provide a fresh perspective on these intertwined
interactions using the novel approach of Higgs spectroscopy, i.e. an
investigation of the amplitude oscillations of the superconducting order
parameter driven by a terahertz radiation. Uniquely for cuprates, we observe a
Fano interference of its dynamically driven Higgs mode with another collective
mode, which we reveal to be charge density wave fluctuations from an extensive
doping- and magnetic field-dependent study. This finding is further
corroborated by a mean field model in which we describe the microscopic
mechanism underlying the interaction between the two orders. Our work
demonstrates Higgs spectroscopy as a novel and powerful technique for
investigating intertwined orders and microscopic processes in unconventional
superconductors
Perspectives of microwave quantum key distribution in open-air
One of the cornerstones of quantum communication is the unconditionally
secure distribution of classical keys between remote parties. This key feature
of quantum technology is based on the quantum properties of propagating
electromagnetic waves, such as entanglement, or the no-cloning theorem.
However, these quantum resources are known to be susceptible to noise and
losses, which are omnipresent in open-air communication scenarios. In this
work, we theoretically investigate the perspectives of continuous-variable
open-air quantum key distribution at microwave frequencies. In particular, we
present a model describing the coupling of propagating microwaves with a noisy
environment. Using a protocol based on displaced squeezed states, we
demonstrate that continuous-variable quantum key distribution with propagating
microwaves can be unconditionally secure at room temperature up to distances of
around 200 meters. Moreover, we show that microwaves can potentially outperform
conventional quantum key distribution at telecom wavelength at imperfect
weather conditions.Comment: 13 pages, 6 figure
Research data: Fano interference between collective modes in cuprate high-Tc superconductors
Research data and metadata that was used in the corresponding publication "Fano interference between collective modes
in cuprate high-Tc superconductors" ( https://doi.org/10.1038/s41467-023-36787-4 )