Cologne experiment backs a theoretical route to topological quantum computing

[Kane]

Researchers in Germany have found experimental support for a long standing idea about topological qubits. The Quantum Insider reports on work from the University of Cologne, published in Science Advances, that studied Josephson junctions made from topological insulators

The experiment was led by Dr Jakob Schluck and Ella Nikodem in Professor Yoichi Ando's Topological Matter Laboratory, with simulations from Professor Fabian Hassler's group at RWTH Aachen. Both groups belong to the ML4Q Cluster of Excellence

Using tunnelling spectroscopy while varying the superconducting phase, the team observed highly transmissive Andreev states that concentrated in specific regions when a magnetic field was applied. That behaviour matches the Fu and Kane model proposed in 2008, which describes how topological superconductivity could emerge in such devices

Ando said the results are essential for assessing the potential of these junctions for topological quantum computing, and Nikodem said the experimental results align very well with theoretical predictions. The key signature of topological superconductivity, a gap closing and reopening, has not yet been seen, and Schluck said the team needs better energy and time resolution

Topological qubits promise natural protection against errors, but evidence has been hard to pin down. Matching a well known theory this closely is a valuable step, even if the decisive proof is still to come. It is careful, incremental science of the kind the field needs

Will topological qubits ever become practical? And how close is the field to confirming Majorana zero modes?

Experiment Supports Theoretical Path to Topological Quantum Computingthequantuminsider.com

[Sharon96]

Cologne and Aachen working together shows the strength of German quantum research. ML4Q has produced some excellent results. Collaboration pays off. Resolution improvements take years