Speed of Light Could Be Dropped to Zero Using Crystals

 

The speed of light in a vacuum, such as space, is little over 186,280 miles per second. Scientists have now demonstrated that, regardless of frequency or bandwidth, it is possible to slow it down to zero miles per second without diminishing brightness.

According to Phys.org, a team of researchers from the Israel Institute of Technology and the Brazilian Institute of Pure and Applied Mathematics discovered a method for theoretically slowing down the speed of light by utilising "exceptional points"—coordinates where two separate light emissions meet and merge into a single one. The finding was described in a report published in the scientificjournal Physical Review Letters.

Slow-light technologies have the potential to help us improve our telecommunications infrastructure and quantum computers. According to the current report, existing research reveals that light may be slowed to an infinitesimal fraction of its vacuum speed by trapping it inside either ultracold atom clouds or photonic crystal waveguides.

The first entails directing a laser into a cloud of ultracold sodium atoms, according to the researchers' study. A slow pulse of light is imprinted into the atoms when the laser is quickly turned off, thus bringing the light to a halt by absorbing it; the imprinted shape can then be converted back into a photon. The researchers were able to make their breakthrough using the second strategy.

According to Reader's Digest, photonic crystals are materials perforated with billions of microscopic holes through which light refracts. A waveguide, on the other hand, is a restricting tube-like structure that, as the name implies, guides the waves that are delivered through it (any kind of waves, but in this case optical waves).

The difficulty is that slowing light down tends to reduce its intensity. The researchers observed that if a waveguide is designed with parity-time symmetry, a relatively new notion that refers to maintaining a constant balance, or symmetry, between a system's energy losses and gains, such losses can be minimised.

When light arrives at an exceptional point, where two incoming sources converge into a single channel, parity-symmetric waveguides can keep the light's intensity constant and symmetric. That means we could now not only halt the light and hold it there, but also release it and ramp it back up to its normal speed without losing any of its intensity—a level of consistency and control that prior models couldn't match.

According to Phys.org, the technology may be adapted to light of any and all frequencies and bandwidths by altering the gain-loss settings, making it far more versatile than previous light-stopping technologies. The researchers believe that the technique might work for other types of waves as well, such as sound.