  Entanglement-enhanced quantum metrology explores the utilization of quantum
entanglement to enhance measurement precision. When particles in a probe are
prepared into a quantum entangled state, they collectively accumulate
information about the physical quantity to be measured, leading to an
improvement in measurement precision beyond the standard quantum limit and
approaching the Heisenberg limit. The rapid advancement of techniques for
quantum manipulation and detection has enabled the generation, manipulation,
and detection of multi-particle entangled states in synthetic quantum systems
such as cold atoms and trapped ions. This article aims to review and illustrate
the fundamental principles and experimental progresses that demonstrate
multi-particle entanglement for quantum metrology, as well as discuss the
potential applications of entanglement-enhanced quantum sensors.
