Amplification of electromagnetic waves by a rotating body

This is a blue-sky research proposal that aims to provide the first experimental evidence of a 50-year-old prediction in fundamental physics: the amplification of electromagnetic (EM) waves in the interaction with a rotating metallic or absorbing sphere.

The importance of demonstrating this effect lies, in a first instance, in the underlying physical concept that mechanical rotation can induce the creation of negative frequencies. The presence of these negative frequencies is what causes the transition from absorption to gain and hence amplification of reflected waves. This prediction was first made by Zel'dovich in 1971 and is tightly connected to Roger Penrose's proposal in 1969 that it might be possible to extract energy from a rotating black hole. Zel'dovich's idea involving EM waves, has never been verified experimentally due to the apparently impossible technological barrier in realizing the amplification condition: the mechanical object rotation rates need to be faster than the oscillation frequency of the EM wave.

The investigators have made a breakthrough discovery in the past 12 months that resolves the technological issue by resorting to evanescent field coupling to the absorbing object. This concept has been theoretically and experimentally verified with sound waves and theoretically extended to EM waves in a superconducting circuit.

Looking forward, we aim to implement experiments that will show amplification of superconducting circuit modes that enclose and are evanescently coupled to a levitated metallic microsphere rotating at MHz frequencies. We will also study how achieving this will pave the way to observing the amplification and detection of quantum EM fluctuations, thus potentially providing new and exciting routes towards single photon interactions in superconducting circuits.