Disorder-induced enhancement of precision in quantum metrology
We find that insertion of glassy disorder, accidental or engineered, can lead to enhancement of metrological precision in estimating an unknown parameter of a quantum system. We compare the Fisher information-based lower bound of the minimum standard deviation of an estimated parameter, in presence of glassy disorder in the system, with the same of an ideal, viz. disorder-free, situation. We find instances where the disorder-averaged error in estimation outperforms the same for a disorder-less scenario for uncorrelated as well as copies of two-qubit maximally entangled probes. The advantage in the accuracy of measurement obtained in a disordered situation over the ideal one is often greater than the corresponding dispersion of the disorder-induced error distribution, and in such cases, we refer to the effect as an example of "order from disorder". Moreover, disorder insertion can reduce the requirement of entanglement content of the initial probes, which are copies of two-qubit states, along with providing a disorder-induced enhancement.