Talk given by

Muhammad Irfan
Kavli Institute of Nanoscience

Delft University
The Netherlands

Abstract:

Response of superconductor-normal-metal-superconductor junctions to a magnetic 
field is complicated and non-universal because all trajectories contributing to 
the supercurrent have a different effective area, and therefore acquire 
arbitrary magnetic phases. We design an hourglass-shaped Josephson junction 
where due to the junction symmetry the magnetic phase of every trajectory is 
approximately equal. By doing so we are able to increase a critical field of the 
Josephson junction to many flux quanta per junction area. We then analyze how 
breaking the symmetry condition increases the sensitivity of the junction, and 
show that our device allows detecting supercurrent carried by ballistic 
trajectories of Andreev quasiparticles.