Majorana Particles

Speaker:      Leo Kouwenhoven (Department of Quantum Nanoscience, TU Delft)

Subject:       Majorana particles

Location:     Auditorium TU Delft

Date:            Friday, November 28, 13:45-14:40

Author:        Jasper Veerman

On Friday, November 28, Leo Kouwenhoven spoke about his work on Majorana particles. These particles, which are their own antiparticles, are rather special. They are fermions, but with the three unusual properties: no charge, no energy and no spin. The particles are the equal superposition of an electron and a hole (absence of an electron). This makes measuring them difficult, but not impossible. By connecting a semiconducting nanowire to a conductor on one side and a superconductor on the other side, Kouwenhoven’s group observed the above mentioned ‘3 times nothing’ criterion for some particles in the experiment. These particles, at the ends of the interface between the nanowire and the superconductor, are likely to be Majorana particles.

To demonstrate the use of this discovery, imagine two Majorana particles. If we exchange their places, we can understand that the conditions have changed. However, if we exchange them again – back into their original position – we would expect the net result to be ‘zero’. In contrast to this expectation, actual exchanges of Majorana particles result in a phase shift, meaning the particles have some memory of what has happened to them. This makes the Majorana particles interesting for application in a quantum computer, since the information in these interactions can be used to form bits. In practice, the particles function in pairs, making them more robust. The Dutch government and Microsoft are now funding Kouwenhoven’s group to develop this computer.

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