Sound is usually treated as the most familiar of physical phenomena, the background noise of daily life rather than a frontier of fundamental physics. Yet in laboratories around the world, carefully ...

The quantum ground state of an acoustic wave of a certain frequency can be reached by completely cooling the system. In this way, the number of quantum particles, the so-called acoustic phonons, which ...

A team of physicists has created a cloud of ultracold atoms that stubbornly resists the most basic rule of everyday experience: when you pump energy into something, it heats up. Instead, this quantum ...