Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity: Poster Session
TT 30.23: Poster
Donnerstag, 8. September 2022, 15:00–18:00, P1
Bloch oscillation effects in ultrasmall Josephson junctions embedded in high-inductance environment — •Fabian Kaap and Sergey Lotkhov — Physikalisch-Technische Bundesanstalt, Bundesallee 100 38116, Deutschland Braunschweig
The adiabatic transport of Cooper pairs, also known as Bloch oscillations(BO), can be of high interest in future applications for metrology, due to the fundamental current-to-frequency relation, IB = 2e × fB. In order for the BO in ultrasmall Josephson junctions to be observed, one has to suppress the quantum fluctuations of charge by means of embedding the junctions into a high impedance environment.
For this purpose, we elaborated a dedicated inductively-resistive planar biasing circuit, which includes high-kinetic-inductance meanders made from granulated aluminium and high-ohmic microstrips of partially oxidized titanium. Using this approach, we were able to measure the characteristic back-bending in an IV-curve of a dc-biased SQUID with Josephson junction of sub-100nm-sizes. By varying the ratio of the Josephson energy EJ and the charging energy EC, using an external magnetic field, we were able to manipulate the shape of the IV-curves back-bending, which can be explained by a modification of the lowest Bloch energy band of Cooper pairs. With this biasing technique the way is paved to circumvent the microwave coupling issues hindering the realization of dual Shapiro step experiments.