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PhD studentship on qubit coupling with superconductors

Advertising institute: PGI-9 - Semiconductor Nanoelectronics
Reference number: D139/2017, Physics

Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich has an open PhD student position on qubit coupling with superconductors.

Coupling spin qubits in quantum dots over a long distance is one of the big remaining challenges, when it comes to realizing large scale quantum computer systems. So far only neighboring quantum dot systems were coupled directly by electrostatic means using control gate electrodes. The goal of this project is to investigate the possibility of a long-range coupling of quantum dot spin qubits using superconducting electrodes. Since this approach is rather unexplored up to now, mainly fundamental questions concerning the feasibility of this concept will be addressed. The present project will study the long-range coupling experimentally. A successful demonstration would be of great benefit for the vision of a scalable quantum information processor.

Project description
The project, funded by the German Science Foundation (DFG) is devoted to the experimental work where the coupling of quantum dots is realized in III-V semiconductors. In this approach the quantum dot qubits will be formed in an InAs nanowire using bottom gate electrodes. The long-range coupling of the qubits will be maintained by a superconducting electrode connected to both quantum dots. In order to obtain a well-controlled interface between the superconductor and the quantum dot, an in-situ process scheme will be employed. Two different coupling mechanisms will be explored, i.e. coupling by means of excited quasiparticles above the superconducting band gap and by crossed Andreev reflection.
The project will involve the preparation of samples using electron beam lithography, wet and dry etching, as well as lift-off processes. Sample and device preparation will be carried out at the clean room of the Helmholtz Nano Facility at Forschungszentrum Jülich. The transport experiments will be carried out in the low temperature laboratory of PGI-9 using dilution refrigerators. Within the project a fellow Ph.D. student at RWTH Aachen University will work on realizing superconducting coupling of Si-based quantum dots.

Job requirements
We welcome applications from candidates with a Master degree in physics and with a background and interest in transport and nanofabrication. Candidates must have a strong aptitude in experimental physics and the drive and capacity to work independently. A theoretical background in solid state physics is required. Familiarity with programming is highly desirable.

Conditions of employment
We offer a 65% appointment (E13) for three years. The successful candidate will be enrolled and graduate with a PhD from the Department of Physics at RWTH Aachen.

Forschungszentrum Jülich aims to employ more women in this area and therefore particularly welcomes applications from women. We also welcome applications from disabled persons.

Information and application
The deadline for application is 30th November 2017. Please contact Prof. Thomas Schäpers ( to apply or for more information. The application should contain the following documents:

  • Application letter.
  • Curriculum vitae including two names of potential referees.
  • Grade transcripts and BSc/MSc diploma (typically B.Sc. and M.Sc.).

Prof. Thomas Schäpers
Peter Grünberg Institute 9
Forschungszentrum Jülich