Alladi Ramakrishnan Hall

Inhomogeneous Superconductors: From Collective (Higgs, Goldstone) Modes to Applications in Quantum Nano-devices

Dr Abhisek Samanta

Ohio State University, US

Abstract: One of the most fascinating examples of interplay between interaction and localization is the destruction of superconductivity in thin-films due to disorder, leading to Superconductor-Insulator transition (SIT). This transition is driven by the dynamical fluctuations of the amplitude (Higgs) and the phase (Goldstone) modes of the pairing order parameter. We study the evolution of these collective modes with disorder and temperature, focusing on their visibility as low-energy sub-gap excitations in spectroscopies and optical responses. Furthermore, I will discuss the effects of strong thermal fluctuations leading to superconducting gap filling instead of gap closing. I will end with promising future applications of low-density superconducting nanowires as various quantum nano-devices, such as single-photon detectors, superconducting qubits, etc.