Artificially rotating system reflects radiation like a black hole
Rotational super-radiance observed for twisted radio waves The post Artificially rotating system reflects radiation like a black hole appeared first on Physics World .
A team at the City University of New York has created an artificially rotating device that reflects radio waves like a black hole, amplifying them by up to six times. The experiment, inspired by rotating black holes and predicted over half a century ago, involves creating an artificial rotation through periodic changes in a network of resonators.
The device, which is three small electrical circuits wired into a loop, mimics the rotation of a black hole and allows for the amplification of specific radio waves. The amplification occurs in special windows, called angular-momentum bandgaps, where the synthetic rotation overtakes the wave. The amplified signals return with the opposite twist and are stronger than before, a key signature of rotational super-radiance.
The researchers fed a 100 MHz radio signal into the loop and observed the amplification effect above 100 MHz. The amplification is selective to the input wave's angular momentum and can feed on waste, giving more gain when the circuit is leakier. While the experiment does not study actual black holes or quantum gravity, it offers a controllable platform for testing physical principles involved in rotational energy extraction.
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