164 citations · 2.8k across the 88 of their papers we have counts for
43 papers · 1 filter
Resonance inversion in a superconducting cavity coupled to artificial atoms and a microwave background
Juha Leppäkangas, Jan David Brehm, Ping Yang +4
We demonstrate how heating of an environment can invert the line shape of a driven cavity. We consider a superconducting coplanar cavity coupled to multiple artificial atoms. The m…
Multiplying and detecting propagating microwave photons using inelastic Cooper-pair tunneling
Juha Leppäkangas, Michael Marthaler, Dibyendu Hazra +5
The interaction between propagating microwave fields and Cooper-pair tunneling across a DC voltage-biased Josephson junction can be highly nonlinear. We show theoretically that thi…
Creating photon-number squeezed strong microwave fields by a Cooper-pair injection laser
Martin Koppenhöfer, Juha Leppäkangas, Michael Marthaler
The use of artificial atoms as an active lasing medium opens a way to construct novel sources of nonclassical radiation. An example is the creation of photon-number squeezed light.…
Electronic Decoherence of Two-Level Systems in a Josephson Junction
Alexander Bilmes, Sebastian Zanker, Andreas Heimes +5
The sensitivity of superconducting qubits allows for spectroscopy and coherence measurements on individual two-level systems present in the disordered tunnel barrier of an $\mathrm…
Superconducting quantum metamaterials as active lasing medium: Effects of disorder
Martin Koppenhöfer, Michael Marthaler, Gerd Schön
A metamaterial formed by superconducting circuits or quantum dots can serve as active lasing medium when coupled to a microwave resonator. For these artificial atoms, in contrast t…
Decoherence and Decay of Two-level Systems due to Non-equilibrium Quasiparticles
Sebastian Zanker, Michael Marthaler, Gerd Schön
It is frequently observed that even at very low temperatures the number of quasiparticles in superconducting materials is higher than predicted by standard BCS-theory. These quasip…