FONDAMENTAUX DE MESURE DE LA VIE: LA DUPLICATION D'UNE CELLU
LE
'Seeing' through paint
Measuring the Transmission Matrix in Optics:
A Viewpoint on:
Majorana fermions in a tunable semiconductor device
Ettore Majorana [1], guided by principles of simplicity and mathematical
elegance, proposed a modification to the Dirac equation describing a spin-1/2 particle that would admit purely real (as opposed to complex-valued) solutions.
Such real solutions have become known as Majorana fermions and describe a class of particles that are, curiously, their own antiparticles (more on this below). There are compelling theoretical reasons to believe that neutrinos are Majorana fermions but a convincing experimental proof is yet to be given [2]. Over the past decade Majorana fermions have been increasingly studied in condensed matter physics where they can appear as emergent degrees of freedom in certain systems of interacting electrons. This means that at low energies the system behaves as if composed of Majorana fermions and not the constituent electrons. In this context, the interest in Majorana fermions stems from their exotic properties (such as the non-Abelian exchange statistics) that could find uses in future applications to fault-tolerant quantum information processing. Jason Alicea of the California Institute of Technology, US, in a paper in Physical Review B [3], describes the most recent and by some measures perhaps the most promising of the proposals to realize and control Majorana fermions in a solid-state system.
Majorana fermions are more easily understood in the “second quantized” notation.
Race for Majorana fermions
...It turns out that this “half-state” has properties of the Majorana fermion....
.....
Recent theoretical proposals to engineer two-dimensional quantum phases of electronic matter that behave as topological superconductors [3, 7, 8] give hope that the elusive Majorana particles, predicted more than 70 years ago, will soon be realized in a tabletop experiment. Which of the proposed schemes will ultimately lead to a useful device is difficult to predict. Proposals by Sau et al. [8] and by Alicea [3] build upon recent theoretical advances but use rather conventional ingredients whose physics and technological aspects are well understood, which might give them an edge in the race for the first experimental realization. The Fu-Kane proposal [7] is conceptually simpler and more elegant, but the technology based on topological insulators, which constitute the key ingredient here, is still in its infancy. On the other hand, discoveries of new families of topological insulators are reported on a regular basis [10, 11] and it appears that it is only a matter of time for an ideal material to emerge. In any case, it is clear that the race for Majoranas is now in its final stretch.
References
Viewpoint
Cloak of invisibility takes a step forward
maya12-21-2012-More on ABC News
ABC News – 'Invisibility Cloak'
May Soon Be Reality
Will Time Travel Ultimately Prove to be Impossible?
its already a time-loop
"Real knowledge is to know the extent of one's ignorance."
~Confucius