Quantum Sensing And Energy Storage

Quantum mechanics has a history of more than 100 years since its establishment in the early 20th century.During its development period,many branch disciplines emerged one after another.Quantum informatics,as an interdisciplinary subject of the quantum mechanics and informatics,is one of them.In this paper,we study and discuss several problems in the quantum informatics,including quantum sensing,energy storage.In the study of quantum sensing,we focused on the multi-atom Sagnac inter-ferometer.We investigate quantum sensing of rotation with a multiatom Sagnac interferometer and present multipartite entangled states to enhance the sensitivity of rotation frequency.In order to find the appropriate initial state and improve the measurement accuracy of the multi-atom Sagnac interferometer,we firstly give the generator with respect to the rotation frequency.Taking advantage of the generator,we investigate the general QFI with respect to rotation frequency for different initial states.By comparing the QFI for different initial states,we find that the initial state in which all the degrees of freedom are entangled is more sensitive than the partially entangled state on estimating the rotation frequencyThe energy-store system so called Quantum battery are investigated.The quan-tum battery we consider is achieved by harmonic oscillator.In such system,the charging process and discharging process are the issue of interest.We study how to increase the charging capacity and charging power of quantum batteries.Besides,the Landau-Zener transition based discharging process is investigated.We find that the extract power of the Landau-Zener transition based discharging process become more continuous and stableAdditionally,we study the representation of quantum states.Based on the coherent-state approach for Majorana representation,we study the superposition of the two coherent states(STCS)in Majorana representation.It is found that the representation of STCS is a closed curve that always passed through the North Pole on the Bloch sphere,and the analytical result of the curve is also given.