The particles of the the Standard Model and its simplest supersymmetric version. [Credit:  Pauline Gagnon]

The particles of the the Standard Model and its simplest supersymmetric version. [Credit:
Pauline Gagnon]

Symmetry and elegance have proven to be a very successful way to think about the physical Universe. Arguably the greatest successes in 20th century particle physics came from translating mathematical symmetries into predictions about the results of particle collisions. However, not every symmetry thus far has led to a successful theory, and one of the frustrations is that a natural consequence of a symmetry in the theory of relativity hasn’t produced the predicted particles. The currently unfulfilled theory is known as supersymmetry (or SUSY), and so far none of its predictions have borne out experimentally.

However, a completely analogous version of SUSY could exist in certain exotic superconductors. This is not built out of elementary particles, but out of interactions between electrons and atoms, giving rise to a set of particle-like quantum excitations known as quasiparticles.

The new paper discussed the idea of emergent SUSY-like behavior in topological superconductors. In these systems (described in more detail in the sidebar story), the interior of the material conducts electricity without resistance, but the outside is an ordinary conductor. The authors argued that experimentally observed magnetic behavior on the conducting surface could be interpreted super symmetrically. It also exhibits a breaking of SUSY due to the fundamental difference in interior and surface behavior of the system.

In this view, the magnetic excitations (acting like bosons) on the surface are SUSY partners with the topological superconductor quasiparticles, which are fermions. [read more…]

Supersymmetry in…superconductors?


(In honor of Terry Pratchett, I almost wrote that “Twisted light? Onna chip?”, but that would probably confuse 90% of my readers.)

Light is used to carry data, but mostly we don’t use the properties of the photons themselves to convey information. Quantum communication, among other applications, could use the state of the photon to encode data. In particular, the orbital angular momentum (OAM) state of a photon, where the photon describes a helix as it travels, can carry a lot of bits. Now researchers have fabricated a silicon chip to make twisted light.

Photons possess a number of quantum properties that can be used to encode information. You can think of photon polarization as like the rotation of a planet on its axis. In this view, the helical shape of the light wave—known as its orbital angular momentum (OAM)—is akin to the planet’s orbit around the Sun. These properties are independent of each other, and of the wavelength of light, so they can be manipulated separately. Whereas polarization occurs as a combination of two possible orientations, the OAM theoretically can have infinite values, though in practice far fewer states are available. Nevertheless, exploiting OAM greatly expands the potentially exploitable quantum states of photons we could put to use.

The researchers created helical OAM states using a ring-shaped chamber fabricated from silicon and mounted on a chip. [Read more….]

Twisted light on a silicon chip