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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.
Abstract
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
mfb said:Majorana 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.
Never underestimate the power of PR.mfb said:Didn't the authors learn anything from the "God particle"? Do we really need this crap again?
Demystifier said:Never underestimate the power of PR.
Now we need the devil particle. Any candidate?
mfb said:They are new in topological superconductors only as far as I know.
Vanadium 50 said:>> So what do you guys think about the 'Angel' particle?
Hype, hype, hype and more hype.
I don't find a reference now, but with ZZ's post we have an even better one.atyy said: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/articl...-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.ZapperZ said:BTW, I think this thread is more suited in the HEP forum than in the QP forum.
mfb said:I don't find a reference now, but with ZZ's post we have an even better one.
I don't think superconductors count as high-energy or particle physics.
mfb said:I don't find a reference now, but with ZZ's post we have an even better one.
mfb said: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.Demystifier said:Never underestimate the power of PR.
Now we need the devil particle. Any candidate?
A propagating Majorana mode is a type of excitation that can occur in certain systems, specifically in topological superconductors. It is characterized by its ability to move through the system without being affected by impurities or defects, making it a promising candidate for applications in quantum computing and information processing.
Unlike other excitations, such as electrons or photons, a propagating Majorana mode is its own antiparticle. This means that two Majorana modes can combine to form a fermion, which has unique properties that make it useful for quantum computing.
The discovery of a propagating Majorana mode would provide strong evidence for the existence of Majorana fermions, which have been predicted by theory but have not yet been conclusively observed. This could have significant implications for our understanding of fundamental particles and open up new possibilities for quantum technologies.
There are several methods for detecting a propagating Majorana mode, including tunneling spectroscopy, Josephson junction measurements, and interferometry. These techniques rely on the unique properties of Majorana fermions to distinguish them from other excitations in the system.
Propagating Majorana modes have potential applications in topological quantum computing, as they are robust against decoherence and can be used to perform quantum operations. They may also have applications in topological quantum wires and sensors, as well as in fundamental research on exotic particles and states of matter.