Quantum measurements and quantum metrology

K.A. Asgarov, Eltaj Yuzbashov

Quantum metrology, being a branch of modern metrology, is a study that provides highresolution and very sensitive measurement of physical parameters by explaining the properties ofphysical systems in terms of quantum theory. By developing new measurement methods, thisfield demonstrates higher accuracy than the same measurements performed in a classical framework.

Waldemar Nawrocki

Jeongwoo Jae, Jiwon Lee, M. S. Kim +2 more

Abstract We demonstrate that the contextuality of measurement selection can enhance the precision of quantum metrology with a simple linear optical experiment. Contextuality is a nonclassical property known as a resource for various quantum information processing tasks. Recent studies show that contextuality by anomalous weak values can be utilized to enhance metrological precision, unraveling the role of contextuality in quantum metrology. Our contextual quantum metrology (coQM) scheme can elevate the precision inferred from the observed Fisher information as much as six times the precision limit given by the quantum Fisher information (QFI), and, when the Godambe information is used, the precision inferred becomes about two times lower than the precision limit. We achieve the contextuality-enabled precision with two mutually complementary measurements, whereas, in the conventional method, some optimal measurements to achieve the precision limit are either theoretically challenging to find or experimentally infeasible to realize. These results highlight that the contextuality of measurement selection is applicable in practice for quantum metrology.

Guo‐Yong Xiang, Guang‐Can Guo

The statistical error is ineluctable in any measurement. Quantum techniques, especially with the development of quantum information, can help us squeeze the statistical error and enhance the precision of measurement. In a quantum system, there are some quantum parameters, such as the quantum state, quantum operator, and quantum dimension, which have no classical counterparts. So quantum metrology deals with not only the traditional parameters, but also the quantum parameters. Quantum metrology includes two important parts: measuring the physical parameters with a precision beating the classical physics limit and measuring the quantum parameters precisely. In this review, we will introduce how quantum characters (e.g., squeezed state and quantum entanglement) yield a higher precision, what the research areas are scientists most interesting in, and what the development status of quantum metrology and its perspectives are.

Waldemar Nawrocki