Whispers of the Majorana particles


Majorana fermions, being their own antiparticles, were first postulated by Ettore Majorana in 1937, purely on mathematical grounds. While ever since no fundamental particle has been found to fulfill Majorana's prediction, such fermions were theoretically shown to exist in engineered solid state systems as ?half-electron and half-hole? quasiparticles pinned to zero energy.
A recent experimental work in our group (V. Mourik et al, Science, 2012) confirmed the presence of Majorana fermions in semiconductor nanowires proximity coupled to an island of superconductor. The interplay of the internal spin-orbit field and an external magnetic field creates the zero energy mode, which was detected by tunnel spectroscopy measurements.
Here I propose an architecture to give a clear and robust signature of Majorana fermions by capturing the characteristic Josephson radiation of voltage-biased superconducting junctions. As opposed to conventional Cooper pair tunneling, Majorana states allow for the coupling of single electron charges, emitting radiation with one half of the Josephson frequency. This unique high frequency signal, the ?whispers? of the Majorana particles, will give an unambiguous proof for their presence in the measurement circuit.
Considering the typical frequency range of 30 GHz to 300 GHz set by the superconducting gap, I will utilize on-chip superconducting radiation detectors, where no high frequency off-chip elements are required, and the presence of the irradiation is observed in the DC I-V curve of the detector. This scheme makes the detection of very high frequency signals compatible with temperatures in the range of 10 mK and well-shielded environments required for observing coherent quantum effects.
My previous experience with low-noise transport measurements at millikelvin temperatures well matches the requirements of the proposed research which is an integral part of the efforts towards topological quantum computation utilizing Majorana particles in the research group of Prof. Leo Kouwenhoven.


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Dr. A. Geresdi

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Technische Universiteit Delft, Faculteit Technische Natuurwetenschappen, NanoScience - Kavli Institute of Nanoscience Delft


Dr. A. Geresdi


01/10/2014 tot 30/09/2017