Researchers have employed lasers and a sophisticated optical system to create something we have never seen before, a quasiparticle that behaves like it has negative mass. This breakthrough could improve both lasers and their applications as well as help us be understood by this almost-sci-fi topic.
The object in question is a quasiparticle called a trion-polariton, a peculiar interaction between photons and electromagnetic field being developed by certain electron configurations in a semiconductor, another quasiparticle known as an exciton. Quasiparticles behave just like regular particulate matter and they are very useful in forefront physical research. What scientists have observed, as reported in Nature Physic, is a polariton that acts like it has negative mass.
Just to give you a sense of what something with negative mass would do, consider that if you were to pull something towards you, if it had negative mass it would accelerate away from you.( It is not clear, at the moment, if cats are made of negative mass particles .)
“By making an exciton to give up some of its identity to a photon to create a polariton, we end up with an object that has a negative mass associated with it, ” senior writer Professor Nick Vamivakas, from Rochester University, said in a statement. “That’s kind of a mind-bending thing to think about because if you try to push or pull it, it will go in the opposite guidance from what your intuition would tell you.”
The set-up itself is very interesting. A laser is shot inside an optical microcavity where it is limited. In there, they place a semiconductor that generates the exciton. The exciton then interacts with trapped lighting to generate the polariton.
Negative mass deliberations are often associated with warp drives and wormholes but I’m afraid this won’t help solve either. But it seems like it could be engaged in producing most efficient lasers because it’s possible to get light out of the polaritons with a lot less energy than in a regular laser.
“With the polaritons, we’ve created with this machine, the prescription for get a laser to operate is completely different, ” Vamivakas explained. “The system starts lasing at a much lower energy input.”
Even more applications of such a peculiar quasiparticle might be on the way, but the team wants to first understand the polaritons’ behavior and how to exploit it.
“We’re daydream up ways to apply pushes and pulls–maybe by utilizing an electrical field across the device–and then investigating how these polaritons move around in the machine under application of external force, ” Vamivakas concluded.
Negative mass particles might not be there to power your spaceship, but maybe soon they can make our lasers more energy efficient.