All matter you have ever interacted with has mass, and as such, obeys the universal laws of motion , enunciated by Isaac Newton centuries ago. If you push something, it will move in the direction you push it. However, matter with negative mass would do the complete opposite. Instead of reacting in a predictable way when force is applied, objects with negative mass react the opposite of what you would expect. What seems so unusual to us has become a reality, as a team of researchers from the University of Rochester (USA) has devised a way to create negative mass particles using lasers.
Experts have created negative mass particles in an atomically thin semiconductor, causing it to interact with light confined in an optical microcavity.
This is just “interesting and exciting from a physical perspective, but it also turns out that the device we created presents a way to generate laser light with an incrementally small amount of energy,” says Nick Vamivakas, associate professor of quantum optics and quantum physics at the Rochester Institute of Optics to the journal Nature Physics.
The device consists of two mirrors that create an optical microcavity, which confines light in different colors of the spectrum depending on how the mirrors are spaced. The experts embedded an atomically thin molybdenum diselenide semiconductor in the microcavity.
The semiconductor was positioned in such a way that its interaction with the confined light resulted in small particles of the semiconductor called excitons, which combined with photons from the confined light to form polaritons (particles born from light and matter).
“By having an exciton give up part of its identity to a photon to create a polariton, we end up with an object that has a negative mass associated with it. That’s something to think about, because if you try to push or pull, it will go in the opposite direction to what your intuition would tell you “, clarifies Vamivakas.
Other research groups have been experimenting with similar devices, but this is the first device to produce negative mass particles.
Although applications are yet to come, this lab will continue to explore, for example, how this device could serve as a substrate for producing lasers. “With the polaritons that we have created with this device, the prescription for operating a laser is completely different, ” says Vamivakas. “The system starts working with a much lower power input” than the traditional lasers that are used today.
Another field of research would be the physical implications of creating negative mass in the device. “We are dreaming up ways to apply the push and pull motion, perhaps by applying an electric field through the device, and then studying how these polaritons move in the device under the application of external force,” concludes Vamivakas.
Reference: Anomalous dispersion of microcavity trion-polaritons, S. Dhara, C. Chakraborty, KM Goodfellow, L. Qiu, TA O’Loughlin, GW Wicks, Subhro Bhattacharjee & AN Vamivakas Nature Physics (2017). DOI: 10.1038 / nphys4303
Image credit: Michael Osadciw / University of Rochester
