Mesoscopic Josephson Junctions
-- application of their coherence and charging effect

Department of Applied Physics and Chemistry
Associate Professor Hiroshi SHIMADA
shimada@pc.uec.ac.jp
http://inaho.pc.uec.ac.jp/
 

 

 

Fig. 1 Capacitively coupled arrays of small Josephson junctions. Each array is composed of serially connected parallel two-junctions pairs.

 

In my group quantum transport phenomena of electrons in mesoscopic systems are studied.

One of the recent topics is a quantum current mirror effect in capacitively coupled arrays of small Josephson junctions (Fig. 1). In such a device a dc current in one array is accurately copied in the other array although both arrays are only capacitively coupled (Fig. 2). This phenomenon is thought of as a combined effect of the coherence in superconductivity and the charging associated with the Cooper pairs tunneling.
We investigate the physical origin of this phenomenon and pursue its metrological applications.

 

Fig. 2 Quantum current mirror effect.

In the threshold region around V2= ±0.4 mV of the I2-V2 characteristic, I1 grows to the same magnitude as I2, although the voltage, V1, on the array 1 is fixed in the Coulomb blockade range.