R. Bosisio | Searcharxiv

arXiv2016

Photonic heat conduction in Josephson-coupled Bardeen-Cooper-Schrieffer superconductors

We investigate the photon-mediated heat flow between two Josephson-coupled Bardeen-Cooper-Schrieffer (BCS) superconductors. We demonstrate that in standard low temperature experiments involving temperature-biased superconducting quantum interference devices (SQUIDs), this radiative contribution is negligible if compared to the direct galvanic one, but it largely exceeds the heat exchanged between electrons and the lattice phonons. The corresponding thermal conductance is found to be several orders of magnitude smaller, for real experiments setup parameters, than the universal quantum of thermal conductance, kappa_0(T)=pi k_B^2T/6hbar.

cond-mat.supr-con↗

arXiv2015

Radiation comb generation with extended Josephson junctions

We propose the implementation of a Josephson radiation comb generator (JRCG) based on an extended Josephson junction subject to a time dependent magnetic field. The junction critical current shows known diffraction patterns and determines the position of the critical nodes when it vanishes. When the magnetic flux passes through one of such critical nodes, the superconducting phase must undergo a $π$-jump to minimize the Josephson energy. Correspondingly a voltage pulse is generated at the extremes of the junction. Under periodic driving this allows us to produce a comb-like voltage pulses sequence. In the frequency domain it is possible to generate up to hundreds of harmonics of the fundamental driving frequency, thus mimicking the frequency comb used in optics and metrology. We discuss several implementations through a rectangular, cylindrical and annular junction geometries, allowing us to generate different radiation spectra and to produce an output power up to $10$~pW at $50$~GHz for a driving frequency of $100$~MHz.

cond-mat.mes-hall↗