Junctionless Cooper pair transistor

TL;DR

This paper demonstrates a superconducting single electron transistor that operates without tunnel junctions, utilizing quantum phase slips in titanium wires to achieve Coulomb blockade modulated by gate potential.

Contribution

It introduces a novel junctionless Cooper pair transistor based on quantum phase slips, eliminating the need for traditional tunnel junctions.

Findings

Coulomb blockade observed and modulated by gate potential

Blockade disappears above critical temperature

Magnetic field can suppress Coulomb blockade at low temperatures

Abstract

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\pi. 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 superconducting single electron transistor (Cooper pair transistor) without any tunnel junctions. Instead a pair of thin superconducting titanium wires in QPS regime were used. The current-voltage characteristics demonstrate the clear Coulomb blockade with magnitude of the Coulomb gap modulated by the gate potential. The Coulomb blockade disappears above the critical temperature, and at low temperatures can be suppressed by strong magnetic field.