Splitting photons makes a new form of light possible

Shattering light into so-called Majorana particles, something that has long been thought to be impossible, may turn out to be possible after all.

There may still be an impossible kind of light. To generate this light, you would have to split a photon (a light particle) to produce what are called Majorana bosons.

In 1937, Italian physicist Ettore Majorana suggested that some electrons, which belong to the class of fermions in particle physics, can split into two theoretical particles called Majorana fermions. Electrons are not physically broken in half. Instead, quantum effects make it appear as if the electron has split.

heads or tails

Together, these two halves still make up the same electron. However, they are spatially separated from each other and thus can be seen as different objects, like two sides of a coin or two feet of the same pants. “It’s like taking a pair of pants and loosening both legs as far apart as possible. They’re still the same pants, but both ends are far apart,” said Lorenza Viola, a professor of theoretical physics at Dartmouth College in New Hampshire.

Viola and her colleagues have now extended the concept of Majorana particles to bosons. Photons also belong to this class of particles. Prior to this, Majorana bosons were considered mathematically impossible.

“Much of our previous work has focused on exposing every possible way to do this,” said Vincent Flynn, a member of Viola’s research team. “It was exciting to finally find the key to making these particles, when most physicists thought they couldn’t exist.”

The trick to making Majorana bosons, according to the researchers’ calculations, is to leak a small amount of energy from the system, rather than isolating it as needed for Majorana fermions. For photons, this system would be a series of adjacent cavities, filled with light. This will create Majorana photons at both ends of the chain. This would be a completely new form of light.

tangle

Since each Majorana boson pair belongs to one particle, changing one particle will directly affect the other as well. This is due to quantum entanglement. There are long-range interactions of certain properties throughout the chain, and they get stronger as the chain grows and the particles move apart. These are exciting “mysterious forces at a distance,” Viola says, referring to Einstein’s description of quantum entanglement.

The result is that the light shining at the end of such a string exits on the other side stronger than it enters.

This could be useful in making quantum computers more resistant to external disturbances, says Alex Ruichao Ma, a quantum physicist at Purdue University in Indiana, USA. “If you use two main particles to encode quantum information, you can’t lose that information if only one of the particles is missing,” Ma says.

Viola and her colleagues have only shown that Majorana bosons are theoretically possible. The next step is their work in the laboratory.

It will certainly be possible in the near future to build a small system to test these ideas. “Creating more complex systems where you can actually use the Majorana bosons is very long-term,” Ma says.