Sensitivity and linearity of superconducting radio-frequency single-electron transistors: effects of quantum charge fluctuations.
We have investigated the effects of quantum fluctuations of quasiparticles on the operation of superconducting radio-frequency single-electron transistors (rf-SETs) for large values of the quasiparticle cotunneling parameter alpha = 8EJ/Ec, where EJ and Ec are the Josephson and charging energies. We find that, for alpha > 1, subgap rf-SET operation is still feasible despite quantum fluctuations that wash out quasiparticle tunneling thresholds. Surprisingly, such rf-SETs show linearity and signal-to-noise ratio superior to those obtained when quantum fluctuations are weak, while still demonstrating excellent charge sensitivity.
Thalakulam
Madhu
M
Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.
Ji
Z
Z
Rimberg
A J
AJ