arXiv subjects

Valery Yampol'skii

Publications and source records attributed to Valery Yampol'skii.

5 recordsLinked to original sources

arXiv2024

Effect of Charge-neutrality Breaking on Localized Terahertz Waves in a Plate of Layered Superconductor

We study analytically the effect of charge-neutrality breaking on the spectrum of localized Josephson plasma waves (JPWs) in a plate of layered superconductor of finite thickness for the case of layers parallel to the interface. This effect results in the appearance of additional eigenmodes with anomalous dispersion and an additional forbidden region in the spectrum of localized modes near the Josephson plasma frequency. We consider both the surface and waveguide eigenmodes with symmetric and anti-symmetric field distribution with respect to the middle plane of the superconducting plate.

cond-mat.supr-con↗

arXiv2014

Lamb-Dicke spectroscopy of atoms in a hollow-core photonic crystal fibre

Unlike photons, which are conveniently handled by mirrors and optical fibres without loss of coherence, atoms lose their coherence via atom-atom and atom-wall interactions. This decoherence of atoms deteriorates the performance of atomic clocks and magnetometers, and also hinders their miniaturisation. Here we report a novel platform for precision spectroscopy. Ultracold strontium atoms inside a kKagome-lattice hollow-core photonic crystal fibre (HC-PCF) are transversely confined by an optical lattice to prevent atoms from interacting with the fibre wall. By confining at most one atom in each lattice site, to avoid atom-atom interactions and Doppler effect, a 7.8-kHz-wide spectrum is observed for the $^1 S_0-{}^3P_1$ (m=0) transition. Atoms singly trapped in a magic lattice in hollow-core photonic crystal fibresHC-PCFs improve the optical depth while preserving atomic coherence time.

physics.atom-ph↗

arXiv2005

Generation of tunable Terahertz radiation using Josephson vortices

We propose how to control the THz radiation generated by fast moving Josephson vortices in spatially modulated (either along the c-axis or the ab-plane) samples of Bi-2212 and related superconducting compounds. We show that the JVs moving in a subset of weaker junctions can generate out-of-ab-plane and outside-the-cone Cherenkov radiation. The ab-plane modulation of superconducting properties (achieved, for instance, by ion irradiation lithography) can result in transition radiation within certain frequency windows, i.e., allowing the design of tunable THz emitters and THz photonic crystals.

cond-mat.supr-con↗

arXiv2005

Generation of tunable Terahertz out-of-plane radiation using Josephson vortices in modulated layered superconductors

We show that a moving Josephson vortex in spatially modulated layered superconductors generates out-of-plane THz radiation. Remarkably, the magnetic and in-plane electric fields radiated are of the same order, which is very unusual for any good-conducting medium. Therefore, the out-of-plane radiation can be emitted to the vacuum without the standard impedance mismatch problem. Thus, the proposed design can be more efficient for tunable THz emitters than previous proposals, for radiation only propagating along the ab-plane.

cond-mat.supr-con↗

arXiv2005

Surface Josephson plasma waves in layered superconductors

We predict the existence of surface waves in layered superconductors in the THz frequency range, below the Josephson plasma frequency $ω_J$. This wave propagates along the vacuum-superconductor interface and dampens in both transverse directions out of the surface (i.e., towards the superconductor and towards the vacuum). This is the first prediction of propagating surface waves in any superconductor. These predicted surface Josephson plasma waves are important for different phenomena, including the complete suppression of the specular reflection from a sample (Wood's anomalies) and a huge enhancement of the wave absorption (which can be used as a THz detector).

cond-mat.supr-con↗