For most Quantum technology applications, the sensitivity of the quantum system to minute external perturbations is harmful, as it leads to decoherence making the system essentially classical. Not so for sensing and metrology applications, where sensitivity is the main requirement, accompanied with appropriate measurement. In fact certain quantum states of many-body systems, such as squeezed or entangled states, lead to greater sensitivity – approaching the Heisenberg limit – to external perturbations, signals or fields, which can be used for quantum enhanced metrology.