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Nanometer-scale tunnel junctions for quantum circuits

Nanometer-scale tunnel junctions for quantum circuits




Dr. Martin Weides


A tunnel junction is a thin dielectric barrier between two electrically conducting
materials. The typical junction thickness is on the order of nanometers while the lateral size is on the order of microns. Superconducting tunnel junctions, i.e., junctions with superconducting electrodes, form a so-called Josephson junction. Such junctions act as non-linear inductance being central to anharmonic resonant circuits such as quantum bits. It was shown that modern generations of superconducting quantum circuits featuring long coherence times require tunnel junctions of lateral dimensions on the order of 50-100 nanometers.

Within the Masterthesis at the Physikalisches Institut quantum bits with nanometer-
scale tunnel junctions will be implemented and studied. The thesis project is embedded in and connects to ongoing research in our group (http://www.phi.kit.edu/ustinov-research.php).

The student will be involved in simulation and design of qubit systems, process the chip at local cleanroom and deposition facilities and measure it in our millikelvin cryostats. She/he will learn circuit quantum electrodynamics, micro and nanotechnology as well as microwave measurement at cryogenic temperatures.

We are looking for highly motivated students with interests in solid state physics and nanotechnology.

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