杏吧原创

A type of light that was previously thought to be impossible may be real after all. Creating it would involve 鈥渟plitting鈥� a single photon of light between two locations to produce particles called Majorana bosons.

In 1937, Italian physicist Ettore Majorana suggested that some electrons, which fall into a category of particles called fermions, could be split into two theoretical particles called Majorana fermions. This wouldn鈥檛 involve physically breaking the electrons in half, but rather using quantum effects to give the electron the appearance of being split.

The two halves would still be part of the same electron, but they would be spatially separate from one another and could be described as separate objects, like two sides of a thick coin or two legs of a single pair of trousers. 鈥淚t鈥檚 like you take a pair of jeans and grab the two legs and stretch the legs as far out as possible. It鈥檚 still one pair of jeans, but the footholes are far apart from one another,鈥� says at Dartmouth College in New Hampshire.

Now, Viola and her colleagues have extended the concept of Majorana particles to bosons, a class of particles that includes photons. Prior to this work, it was thought that making Majorana bosons would be mathematically impossible.

鈥淎 lot of the early things that we were working on were poking holes in every possible way of doing this,鈥� says , part of Viola鈥檚 team at Dartmouth. 鈥淚t was exciting, finally finding the key to realising these things which most people in the field would have said could not exist.鈥�

According to the researchers鈥� calculations, the key to making Majorana bosons is to allow a small amount of energy to leak out of the system, rather than keeping it isolated and contained as is necessary for Majorana fermions. For photons, the system would be a chain of connected cavities filled with light, and the Majorana photons would occur at either end of the chain. This would represent a wholly new phase of light.

Because each pair of Majorana bosons would be part of the same particle, manipulating one of them could affect the measured state of the other due to a quantum correlation called entanglement. 鈥淭here are these long-range correlations of certain properties across these chains, and they actually get stronger as the chain gets longer and the particles get further apart, which is exciting in terms of 鈥榮pooky action at a distance鈥�,鈥� says Viola, referring to Einstein鈥檚 description of quantum entanglement.

One consequence is that light pumped into one end of such a chain of cavities could come out the other end stronger than it went in.

This could be useful for making quantum computers that are more resilient when perturbed by outside forces, says at Purdue University in Indiana. 鈥淚f you use the two Majorana particles to encode quantum information, then you wouldn鈥檛 be able to destroy that information if you only destroy one of them,鈥� says Ma.

Viola and her colleagues have only shown that Majorana bosons are possible in theory, though 鈥� the next step is to try making them in a laboratory.

鈥淏uilding a small system just to test these ideas out would be certainly possible in the near future, but going to more complex systems where you might be able to actually use Majorana bosons is a bit more long-term,鈥� says Ma.

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