A group of researchers from several institutions and Microsoft reported more progress in the search for the elusive Majorana particle that Microsoft is hoping to use in quantum computing. Microsoft’s ‘topological’ approach, based on the Majorana, is predicted to be more stable and require less error correction than approaches favored by IBM, Google, and others. The recent work, published late March in Nature (Quantized Majorana conductance), demonstrated predicted Majorana attributes with greater confidence.

A good account of the work along with background on the Majorana is posted on Phys.org (Latest nanowire experiment boosts confidence in Majorana sighting) which noted:  “[M]ajorana quasiparticles, are different from ordinary matter like electrons or quarks—the stuff that makes up the elements of the periodic table. Unlike those particles, which as far as physicists know can’t be broken down into more basic pieces, Majorana quasiparticles arise from coordinated patterns of many atoms and electrons and only appear under special conditions. They are endowed with unique features that may allow them to form the backbone of one type of quantum computer, and researchers have been chasing after them for years.

“The latest result is the most tantalizing yet for Majorana hunters, confirming many theoretical predictions and laying the groundwork for more refined experiments in the future. In the new work, researchers measured the electrical current passing through an ultra-thin semiconductor connected to a strip of superconducting aluminum—a recipe that transforms the whole combination into a special kind of superconductor.”

The researchers from Kavli Institute of NanoScience, Delft University of Technology (Netherlands), University of Maryland, UC Santa Barbara, Eindhoven University of Technology, and Microsoft were able to observe so-called zero-mode majorana. The work is fairly dense. Here is their abstract followed by a figure from the paper:

Majorana zero-modes—a type of localized quasiparticle—hold great promise for topological quantum computing. Tunnelling spectroscopy in electrical transport is the primary tool for identifying the presence of Majorana zero-modes, for instance as a zero-bias peak in differential conductance. The height of the Majorana zero-bias peak is predicted to be quantized at the universal conductance value of 2e²/h at zero temperature (where e is the charge of an electron and h is the Planck constant), as a direct consequence of the famous Majorana symmetry in which a particle is its own antiparticle. The Majorana symmetry protects the quantization against disorder, interactions and variations in the tunnel coupling. Previous experiments, however, have mostly shown zero-bias peaks much smaller than 2e²/h, with a recent observation of a peak height close to 2e²/h. Here we report a quantized conductance plateau at 2e²/h in the zero-bias conductance measured in indium antimonide semiconductor nanowires covered with an aluminium superconducting shell. The height of our zero-bias peak remains constant despite changing parameters such as the magnetic field and tunnel coupling, indicating that it is a quantized conductance plateau. We distinguish this quantized Majorana peak from possible non-Majorana origins by investigating its robustness to electric and magnetic fields as well as its temperature dependence. The observation of a quantized conductance plateau strongly supports the existence of Majorana zero-modes in the system, consequently paving the way for future braiding experiments that could lead to topological quantum computing.

Link to Phys.org article: https://phys.org/news/2018-03-majorana-trilogy.html#jCp

Link to Nature paper: https://www.nature.com/articles/nature26142