Einstein would be doubly amazed

1 August 2022

Photo: UHH/R.Schnabel

Quantum-correlated light emodies all the weirdness of quantum physics. Now it is being used to aid in the observation of another exotic phenomenon: gravitational waves.

Einstein predicted the existence of gravitational waves in 1916. However during his later life, Einstein was no longer convinced that gravitational waves existed, see D. Kennefick, Physics Today, September 2005, page 43. Independently of that, Einstein was also concerned with a particular consequence of quantum physics, namely quantum entanglement, or more generally quantum correlation.

Einstein would no doubt be amazed that we are now observing gravitational waves and thereby improving our understanding of the universe, and that the observations are being made with quantum-correlated laser light: Laser light with a squeezed quantum uncertainty.

R. Schnabel, Einstein would be doubly amazed, Physics Today 75(8), 46-51 (2022).