Abstract
The outlook of protected quantum computing spurred enormous progress in the search for topological materials, sustaining a continued race to find the most experimentally feasible platform. Here we show that one of the simplest quantum circuits, the Cooper-pair transistor, exhibits a nontrivial Chern number which has not yet been discussed, in spite of the exhaustive existing literature. Surprisingly, the resulting quantized current response is robust with respect to a large number of external perturbations, most notably low-frequency charge noise and quasiparticle poisoning. Moreover, the fact that the higher bands experience crossings with higher topological charges leads to all the bands having the same Chern number, such that there is no restriction to stay close to the ground state. Remaining small perturbations are investigated based on a generic master equation approach. Finally, we discuss a feasible protocol to measure the quantized current.
Highlights
Topological phases are an important research topic in condensed matter physics [1] most notably with the goal to realize inherently protected quantum computing [2]
Topological materials are very straightforwardly simulated when considering the space spanned by the control parameters of superconducting qubits [54,55,56], where it remains, unclear, how physics related to protected edge states may be observed
We have found that the Cooper-pair transistor hosts topologically nontrivial Chern numbers, giving rise to a quantization of the dc current response, which is precisely steered either to the left or right contact
Summary
Topological phases are an important research topic in condensed matter physics [1] most notably with the goal to realize inherently protected quantum computing [2]. Topological materials are very straightforwardly simulated when considering the space spanned by the control parameters of superconducting qubits [54,55,56], where it remains, unclear, how physics related to protected edge states may be observed Such limitations may be circumvented by recently proposed topological transitions in multiterminal Josephson junctions. We consider the Cooper-pair transistor, consisting of two tunnel junctions with a superconducting island in between; see Fig. 1 This circuit has been studied to a great extent [86,87,88,89,90,91,92,93,94,95,96,97,98,99], the Weyl points it exhibits in its band structure have, to the best of our knowledge, not yet been discussed.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
