Observation of quantum-measurement backaction with an ultracold atomic gas

Understand

Current research on micro-mechanical resonators strives for quantum-limited detection of the motion of macroscopic objects.

• Prerequisite to this goal is the observation of measurement backaction consistent with quantum metrology limits.
• However, thermal noise presently dominates measurements and precludes ground-state preparation of the resonator.
• Here we establish the collective motion of an ultracold atomic gas confined tightly within a Fabry-Perot optical cavity as a system for investigating the quantum mechanics of macroscopic bodies.