Observation of Majorana quantum critical behaviour in a resonant level coupled to a dissipative environment


A quantum phase transition is an abrupt change between two distinct ground states of a many-body system, driven by an external parameter. In the vicinity of the quantum critical point (QCP) where the transition occurs, a new phase may emerge that is determined by quantum fluctuations and is very different from either phase. In particular, a conducting system may exhibit non-Fermi-liquid behaviour. Although this scenario is well established theoretically, controllable experimental realizations are rare. Here, we experimentally investigate the nature of the QCP in a simple nanoscale system-a spin-polarized resonant level coupled to dissipative contacts. We fine-tune the system to the QCP, realized exactly on-resonance and when the coupling between the level and the two contacts is symmetric. Several anomalous transport scaling laws are demonstrated, including a striking non-Fermi-liquid scattering rate at the QCP, indicating fractionalization of the resonant level into two Majorana quasiparticles.





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Publication Info

Mebrahtu, HT, IV Borzenets, H Zheng, YV Bomze, AI Smirnov, S Florens, HU Baranger, G Finkelstein, et al. (2013). Observation of Majorana quantum critical behaviour in a resonant level coupled to a dissipative environment. Nature Physics, 9(11). pp. 732–737. 10.1038/nphys2735 Retrieved from https://hdl.handle.net/10161/19647.

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Gleb Finkelstein

Professor of Physics

Gleb Finkelstein is an experimentalist interested in physics of quantum nanostructures, such as Josephson junctions and quantum dots made of carbon nanotubes, graphene, and topological materials. These objects reveal a variety of interesting electronic properties that may form a basis for future quantum devices.

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