Junctionless Cooper pair transistor
Quantum phase slip (QPS) is the topological singularity of the complex order parameter of a quasi-one- dimensional superconductor: momentary zeroing of the modulus and simultaneous ’slip’ of the phase by ±2 π. The QPS event(s) are the dynamic equivalent of tunneling through a conventional Josephson junction containing static in space and time weak link(s). Here we demonstrate the operation of a su- perconducting single electron transistor ( Cooper pair transistor ) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime was used. The current–voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate po- tential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.