Within quantum technology, a quantum sensor utilizes quantum mechanical phenomena, such as quantum superposition, quantum entanglement, and quantum squeezing, to measure things. If a quantum system is measurable, and it interacts with its environment in a known way, then measurements of that system can provide information about its environment. Theoretically such sensor technology would have precision limited only by the uncertainty principle.The field of quantum sensing deals with the design and engineering of quantum mechanical systems and measurements with potential for better performance than any classical strategy in a number of technological applications. Of the wide range of quantum mechanical systems that can be used as a quantum sensor, most can be classified as photonic systems or solid state systems.