Enhanced quasiparticle lifetime in a superconductor by selective blocking of recombination phonons with a phononic crystal

K. Rostem, P. J. de Visser, E. J. Wollack

When quasiparticles in a BCS superconductor recombine into Cooper pairs, phonons are emitted within a narrow band of energies above the pairing energy at 2$\Delta$. We show that a phono…