Polariton Vortices Created from Laser

[sanman]

I was reading about this latest announcement - a research group has used a laser to create polaritonic vortices:

http://www.laboratoryequipment.com/news/2014/11/laser-creates-quantum-whirlpoolWhat can this type of technology lead to? What could it allow us to do?

The article mentions that such polaritonic vortices could be used to detect minute electromagnetic fields, like what a SQUID can do.

Could this lead to the Star Trek style of remote sensing, whereby even small electromagnetic fields could be detected at a distance? Or will this type of approach always be confined to laboratory instrument devices?

Furthermore, could it be used to enhance things like Molecular Beam Epitaxy or Laser Chemical Vapor Deposition?

 

[Cthugha]

Vortices in polariton condensates were known and have been created before using direct resonant excitation. If you create polaritons using light which carries orbital angular momentum, you directly create vortices. The interesting twist of the experiment presented here is that it works using non-resonant excitation. I will tell you in a moment why that is great.

There are three main supposed applications for polariton condensates:
1) Novel light sources. Sven Höfling who provided the sample for the study already reported the first electrically driven polariton laser earlier this year. However, this is nothing where vortices are particularly useful.
2) Quantum simulation. Some Hamiltonians are just too complex to treat analytically. One approach to get more information is to just simulate the Hamiltonian using a polariton condensate by "imprinting" the Hamiltonian. Then you can see what happens.
3) Optical circuits. Common circuits are lithographically defined and doo not change once they are defined. You can steer polariton flow just like you can steer electron flow and that way you can define reconfigurable circuits. Just change the non-resonant illumination pattern and you get a different functionality and different circuits. Vortices and half-vortices are one possible carrier to move information along, so there may be some research going that way in the future. If you want to follow that path, non-resonant excitation is way better than resonant excitation as you just need one laser to inscribe your desired functionality. For resonant excitation you would need one laser per "circuit element" which is a nightmare in terms of alignment and usefulness.

Sensing of small magnetic fields is an issue, but I am not convinced that polariton condensates are too useful here as they suppress magnetic fields. For sensing of electric fields: well, potentially, but at current I do not see how polariton condensate based devices might become cost efficient. To create cavities of good quality you need MBE, which is not a good technique for mass production. One would need a different material than GaAs - one which still allows for condensation at room temperature (like GaN, ZnO, organic stuff or maybe 2D dichalcogenide systems) - and a cheap way to create the devices to get to the market.

Still, polariton condensates are intrinsically cool stuff.

I do not see how these results might help in terms of MBE or CVD, though.