NMR and NQR Fluctuation Effects in Layered Superconductors

We study the effect of thermal fluctuations of the s-wave order parameter of a quasi two dimensional superconductor on the nuclear spin relaxation rate near the transition temperature Tc. We consider both the effects of the amplitude fluctuations and the Berezinskii-Kosterlitz-Thouless (BKT) phase fluctuations in weakly coupled layered superconductors. In the treatment of the amplitude fluctuations we employ the Gaussian approximation and evaluate the longitudinal relaxation rate 1/T1 for a clean s-wave superconductor, with and without pair breaking effects, using the static pair fluctuation propagator D. The increase in 1/T1 due to pair breaking in D is overcompensated by the decrease arising from the single particle Green's functions. The result is a strong effect on 1/T1 for even a small amount of pair breaking. The phase fluctuations are described in terms of dynamical BKT excitations in the form of pancake vortex-antivortex (VA) pairs. We calculate the effect of the magnetic field fluctuations caused by the translational motion of VA excitations on 1/T1 and on the transverse relaxation rate 1/T2 on both sides of the BKT transitation temperature T(BKT)<Tc. The results for the NQR relaxation rates depend strongly on the diffusion constant that governs the motion of free and bound vortices as well as the annihilation of VA pairs. We discuss the relaxation rates for real multilayer systems where the diffusion constant can be small and thus increase the lifetime of a VA pair, leading to an enhancement of the rates. We also discuss in some detail the experimental feasibility of observing the effects of amplitude fluctuations in layered s-wave superconductors such as the dichalcogenides and the effects of phase fluctuations in s- or d-wave superconductors such as the layered cuprates.Comment: 38 pages, 12 figure

Predicting instrumental mass fractionation (IMF) of stable isotope SIMS analyses by response surface methodology (RSM)

International audienc

Digitized radio-over-fiber transceivers for SDM/WDM back-/front-haul

In this paper we analyze the perspective of digitized radio over fiber (DRoF) fronthaul, showing how to meet the requirements to cope with the future radio access networks (RANs). This entails the introduction of space division multiplexing (SDM) while increasing the flexibility and capacity of the DRoF transceivers.Since the evolution of the DRoF fronthaul is being revised and re-defined, in the blueSPACE project we propose two different DRoF transceiver options. The first option consists on simple transceiver, based on the recent standard specifications and, therefore, expected to be deployed in the short-term. The second options is a more advanced transceiver that features high flexibility, relying on a strong DSP and targeting a long-term deployment. Besides a basic characterization of both solutions, we also analyze additional aspects related to the design and implementation of these two DRoF solutions and their integration into an SDM based RAN. This includes the programmability and interaction with the control plane

Sliceable bandwidth variable transponders for elastic optical networks: The idealist vision

This paper describes the general architecture for a sliceable bandwidth variable transponder as identified within the IDEALIST European project. The capability of generate super-channels (optical connections with several adjacent optical sub-carriers) and the slice-ability (super-channels generated together but independently routed in the network towards different destinations) are the key elements of the considered architecture

SDN-enabled Sliceable BVT Based on Multicarrier Technology for Multi-Flow Rate/Distance and Grid Adaptation

We experimentally demonstrate multiple advanced functionalities of a cost-effective high-capacity sliceable-BVT using multicarrier technology. It is programmable, adaptive and reconfigurable by an SDN controller for efficient resource usage, enabling unique granularity, flexibility and grid adaptation, even in conventional fixed-grid networks

Experimental Demonstration of a Metro Area Network with Terabit-capable Sliceable Bitrate Variable Transceiver using Direct Modulated VCSELs and Coherent Detection

We experimentally demonstrate a disaggregated metro area network that includes new photonic devices, node architectures, and sliceable bandwidth/bitrate variable transceiver, transmitting up to 8×11=88 spatial/spectral channels for a total capacity of 1.676Tb/s.</p

Experimental Demonstration of a Metro Area Network with Terabit-capable Sliceable Bitrate Variable Transceiver using Direct Modulated VCSELs and Coherent Detection

We experimentally demonstrate a disaggregated metro area network that includes new photonic devices, node architectures, and sliceable bandwidth/bitrate variable transceiver, transmitting up to 8×11=88 spatial/spectral channels for a total capacity of 1.676Tb/s.</p

Experimental Demonstration of a Metro Area Network with Terabit-capable Sliceable Bitrate Variable Transceiver using Direct Modulated VCSELs and Coherent Detection

We experimentally demonstrate a disaggregated metro area network that includes new photonic devices, node architectures, and sliceable bandwidth/bitrate variable transceiver, transmitting up to 8×11=88 spatial/spectral channels for a total capacity of 1.676Tb/s.</p