Light, sound, action: Extending the life of acoustic waves on microchips

EurekAlert  May 6, 2020 An international team of researchers (Australia, Germany, Denmark) propose to use phonons to store and transfer information that chips receive from fibre-optic cables. They show a way to counteract the intrinsic acoustic decay of the phonons in a waveguide by resonantly reinforcing the acoustic wave via synchronized optical pulses. They experimentally demonstrated coherent on-chip storage in amplitude and phase up to 40 ns, 4 times the intrinsic acoustic lifetime in the waveguide. Through theoretical considerations, they anticipate that this concept allows for storage times up to microseconds within realistic experimental limitations while maintaining a GHz bandwidth […]

Creating a single phonon in ambient conditions

Nanowerk  October 8, 2019 So far, individual phonons have only been observed at extremely low temperatures and under high vacuum. An international team of researchers (Switzerland, USA – MIT) shot ultrafast laser pulses onto a diamond crystal to excite its atomic lattice into vibrating. By careful design of the experiment, they triggered a collective vibration involving more than 100 billion atoms that exchanged energy with single photons from the laser light. By measuring the energy exchanged by this vibration with single photons, they were able to prove that a single phonon was excited, and confirm that the collective oscillation behaves […]

Researchers calculate that sound has negative mass and negative gravity

Next Big Future  August 17, 2018 It is usually said that sound waves do not transport mass. They carry momentum and energy, and lead to temporary oscillations of the local mass density of any region they happen to pass through, but it is an accepted fact that the net mass transported by a sound wave vanishes. Using an effective point-particle theory, researchers at Columbia University have shown that phonons in zero-temperature superfluids have an effective coupling to gravity, which depends solely on their energy (or momentum) and on the superfluid’s equation of state. This effect is completely equivalent to standard […]