Tom Ohki | Searcharxiv

arXiv2019

Demonstration of a superconducting nanowire microwave switch

The functionality of a nanowire integrated into a superconducting transmission line acting as a single pole single throw switch is demonstrated. The switch has an instantaneous bandwidth from 2 to 8 GHz with more than 10 dB of isolation between the open and closed states. The switch consumes no power in the closed state and $\approx 15~\rm{nW}$ in the open state. The rise and fall response time between open and closed states is approximately $370~\rm{ps}$.

cond-mat.mes-hall↗

arXiv2012

Long-lived, radiation-suppressed superconducting quantum bit in a planar geometry

We present a superconducting qubit design that is fabricated in a 2D geometry over a superconducting ground plane to enhance the lifetime. The qubit is coupled to a microstrip resonator for readout. The circuit is fabricated on a silicon substrate using low loss, stoichiometric titanium nitride for capacitor pads and small, shadow-evaporated aluminum/aluminum-oxide junctions. We observe qubit relaxation and coherence times ($T_1$ and $T_2$) of 11.7 $\pm$ 0.2 $μ$s and 8.7 $\pm$ 0.3 $μ$s, respectively. Calculations show that the proximity of the superconducting plane suppresses the otherwise high radiation loss of the qubit. A significant increase in $T_1$ is projected for a reduced qubit-to-superconducting plane separation.

cond-mat.supr-con↗