Critical current 0-pi transition in designed Josephson quantum dot junctions

Tomas Novotny

Charles University in Prague, Faculty of Mathematics and Physics,
Department of Condensed Matter Physics, Prague, Czech Republic

We report on quantum dot based Josephson junctions designed specifically for measuring the supercurrent. From high-accuracy fitting of the current-voltage characteristics, we determine the full magnitude of the supercurrent (critical current). Strong gate modulation of the critical current is observed through several consecutive Coulomb blockade oscillations thus demonstrating the effect of electronic interaction on the coherent tunneling of the Cooper pairs. The critical current crosses zero close to, but not at, resonance due to the so-called 0-pi transition in agreement with a simple theoretical model.

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