If the theorists are right, the quasiparticle excitations of the 5/2 quantum Hall state share a remarkable collective degeneracy that can be exploited for fault-tolerant quantum computing (see Physics Today, October 2005, page 21). But before experimenters can build even a single logic gate, they need to confirm the 5/2 state’s true nature. And before they do that, they need to trap the 5/2 state within the confines of a gated quantum dot or quantum point contact. That preliminary step has just been carried out. Jeff Miller of Harvard University and his collaborators from Alcatel-Lucent’s Bell Labs, Harvard, and MIT fabricated seven different-sized QPCs out of a semiconductor heterostructure made from gallium arsenide and aluminum gallium arsenide (see figure). Using clever tunings of voltages and magnetic fields, Miller and his collaborators observed the 5/2 state not only in the gallium arsenide bulk of the heterostructure but also...
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1 July 2007
July 01 2007
Citation
Charles Day; Quantum point contact sustains 5/2 quantum Hall state. Physics Today 1 July 2007; 60 (7): 29. https://doi.org/10.1063/1.4796519
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