HEPL /KIPAC Seminars

Monday, September 8, 2014

Pieter de Visser

TU Delft

Quasiparticle Dynamics in Aluminum Superconducting Microwave Resonators

Abstract: Kinetic inductance detectors based on microwave resonators are a relatively new technology for submillimeter and terahertz imaging. These resonators are inherently easy to multiplex, which holds the promise of reading out large arrays with a single pair of cables. The detection mechanism relies on breaking Cooper pairs in a superconducting thin film. Therefore there are two fundamental noise processes associated with these detectors: photon noise and generation-recombination noise of quasiparticles.

We have measured both noise sources in aluminum resonators, which shows one can indeed reach these fundamental noise limits. I will show that measuring these fluctuations gives you rich information about the behavior of the superconductor under various conditions. Recently we have demonstrated at 1.5 THz that the sensitivity of these detectors is sufficient for space based imaging.

I will discuss the experimental setup in which we eliminated background radiation, but can still apply a well-defined terahertz signal. The sensitivity of our microresonator detectors is currently limited by microwave readout power absorption. However, this effect is not just heating. Microwave absorption leads to a non-equilibrium distribution of quasiparticles, which not only creates excess quasiparticles, but also leads to a very peculiar microwave response of the superconductor.

Time: 4:00 – 5:00pm

Location: Physics/Astrophysics Bldg., Kistler Conference Rooms 102/103 (Map)

(Light refreshments available 4:00pm; Presentation begis 4:15pm)

Open to All

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