Quantum magnetometry aims to measure the magnetic field with the highest precision. Although estimation of one component of a magnetic field has been well studied over many decades, the highest precision that can be achieved with entangled probe states for the estimation of all three components of a magnetic field remains uncertain.
Scientists at University of Science and Technology of China (USTC) and Chinese University of Hong Kong obtained the ultimate precision for the estimation of all three components of a magnetic field with entangled probe states under the parallel scheme.
The researchers found that the tradeoff comes from the incompatibility of the optimal probe states, and presented an approach to quantify the tradeoff induced by the incompatibility of the optimal probe states. Using this approach, they obtained the minimal tradeoff and the ultimate precision for the multi-parameter quantum magmetometry under the parallel scheme.
Furthermore, they demonstrated that this ultimate precision limit can be achieved and they constructed the optimal probe states and measurements to achieve it. (Phys.org)
The study has been published in Physical Review Letters.