Magnetic Field Sensing Beyond the Standard Quantum Limit Using 10-Spin NOON States
Jonathan A. Jones, Steven D. Karlen, Joseph F. Fitzsimons, Arzhang Ardavan, Simon C. Benjamin, G. Andrew D. Briggs, John J. L. Morton · Science · 2009
Quantum entangled states can be very delicate and easily perturbed by their external environment. This sensitivity can be harnessed in measurement technology to create a quantum sensor with a capability of outperforming conventional devices at a fundamental level. We compared the magnetic field sensitivity of a classical (unentangled) system with that of a 10-qubit entangled state, realized by nuclei in a highly symmetric molecule. We observed a 9.4-fold quantum enhancement in the sensitivity to an applied field for the entangled system and show that this spin-based approach can scale favorably as compared with approaches in which qubit loss is prevalent. This result demonstrates a method for practical quantum field sensing technology.