Precision measurement with trapped ions

Abstract

Measuring physical quantities with unprecedented precision is one of the most important paradigms to extend our fundamental understanding of nature. With the development of new quantum techniques, quantum systems have become a promising platform along the path to pursue higher accuracy and stability of measurement, while the classical methods are approaching their own limitation. Owing to its high stability, long coherence time and good controllability of quantum states, the trapped ion system has attracted much attention as a promising platform for quantum metrology. Recent progress on quantum control of trapped ions in both the scientific and technological aspects greatly advance the potential applications in precision measurement of various physical quantities. The invention of optical comb with ultra-stable laser brings us a new approach to develop a clock working on optical frequency, and features a much higher precision than microwave. This achievement has the potential reform the definition of the basic unit of the international system of units in the near future. New methods of dynamic decoupling or preparing special dressed states significantly extend the coherence time, such that an ultra-sensitive detection of magnetic field can be achieved. By introducing a spin-dependent kick in the phase space, one may also realize rotation measurement with trapped ions and obtain high accuracy with a chip-size apparatus. In this short review, we introduce the principles and designs of optical clock, magnetometer and gyroscope based on trapped ion systems. Owing to its unique features, this platform presents many advantages which can help improving sensitivity and stability, as well as building transportable devices.