A propagating Majorana mode
Although Majorana fermions remain elusive as elementary particles, their solid-state analogs have been observed in hybrid semiconductor-superconductor nanowires. In a nanowire setting, the Majorana states are localized at the ends of the wire. He et al. built a two-dimensional heterostructure in which a one-dimensional Majorana mode is predicted to run along the sample edge (see the Perspective by Pribiag). The heterostructure consisted of a quantum anomalous Hall insulator (QAHI) bar contacted by a superconductor. The authors used an external magnetic field as a “knob” to tune into a regime where a Majorana mode was propagating along the edge of the QAHI bar covered by the superconductor. A signature of this propagation—half-quantized conductance—was then observed in transport experiments.
Majorana fermion is a hypothetical particle that is its own antiparticle. We report transport measurements that suggest the existence of one-dimensional chiral Majorana fermion modes in the hybrid system of a quantum anomalous Hall insulator thin film coupled with a superconductor. As the external magnetic field is swept, half-integer quantized conductance plateaus are observed at the locations of magnetization reversals, giving a distinct signature of the Majorana fermion modes. This transport signature is reproducible over many magnetic field sweeps and appears at different temperatures. This finding may open up an avenue to control Majorana fermions for implementing robust topological quantum computing.
Science, this issue p. 294; see also p. 252
I think they were still unobserved and the big deal is that they might help to implement topological quantum computing: http://www.physics.upenn.edu/~kane/pedagogical/WindsorLec3.pdfMajorana fermions in superconductors have been seen as early as 1960. This study found a new type of quasiparticle. Great, and certainly amazing for the specific field they are working on. But on a global scale: Add it to the big pile of known quasiparticles.
Could you give a reference for the old stuff? My understanding is they are still not definitely observed. The closest before this was measurements by Leo Kouwenhoven https://www.newscientist.com/article/mg21829160-300-nothing-to-see-the-man-who-made-a-majorana-particle/, but that was not definitive.They are new in topological superconductors only as far as I know.
I don't find a reference now, but with ZZ's post we have an even better one.Could you give a reference for the old stuff? My understanding is they are still not definitely observed. The closest before this was measurements by Leo Kouwenhoven https://www.newscientist.com/article/mg21829160-300-nothing-to-see-the-man-who-made-a-majorana-particle/, but that was not definitive.
I don't think superconductors count as high-energy or particle physics.BTW, I think this thread is more suited in the HEP forum than in the QP forum.
ZapperZ's post are all about recent work, not the 1960s (which is what you wrote in post #5). Also both of ZapperZ's references are about topological superconductors (which is different from what you wrote in post #7).I don't find a reference now, but with ZZ's post we have an even better one.
I think they should call it the Janus particle because it's creation operator is equal to its destruction operator and the end of the wire is topologically connected to it's beginning. But "Janus" would have little emotional appeal to the viewing public.Never underestimate the power of PR.
Now we need the devil particle. Any candidate?