  Quantum entanglement has been generated and verified in cold-atom experiments
and used to make atom-interferometric measurements below the shot-noise limit.
However, current state-of-the-art cold-atom devices exploit separable (i.e.
unentangled) atomic states. This Perspective piece asks the question: can
entanglement usefully improve cold-atom sensors, in the sense that it gives new
sensing capabilities unachievable with current state-of-the-art devices? We
briefly review the state-of-the-art in precision cold-atom sensing, focussing
on clocks and inertial sensors, identifying the potential benefits entanglement
could bring to these devices, and the challenges that need to be overcome to
realize these benefits. We survey demonstrated methods of generating
metrologically-useful entanglement in cold-atom systems, note their relative
strengths and weaknesses, and assess their prospects for near-to-medium term
quantum-enhanced cold-atom sensing.

Quantum Physics;Quantum Gases;Atomic Physics