Using disordered superconductors, like β-Ta, TiN, Hf and PtSi, for MKIDs has the potential to improve the photon absorption efficiency, η, over a broad wavelength range. However, the resolving power, R, of these MKIDs is not higher than 20 at 1µm, while the fundamental Fano limit is around 65. To improve R, the signal-to-noise ratio must be increased. We measure the single photon pulse response of β-Ta MKIDs and show that the pulse duration is limited by disorder in two ways. First, the initial pulse decay is faster than exponential, which we attribute to slow quasiparticle diffusion. Second, the decay time of the pulse tail is faster due to low energetic, localized quasiparticles. Both these effects do not occur in conventional Al at the same experimental conditions. These results imply a trade-off between η and R and shows that improving MKIDs by using disordered superconductors is not straightforward.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.