Recently new approaches for sensing the frequency of time dependent Hamiltonians have been presented, and it was shown that the optimal Fisher information scales as T4. We present here our interpretation of this new scaling, where the relative phase is accumulated quadratically with time, and show that this can be produced by a variety of simple pulse sequences. Interestingly, this scaling has a limited duration, and we show that certain pulse sequences prolong the effect. The performance of these schemes is analyzed and we examine their relevance to state-of-the-art experiments. We analyze the T3 scaling of the Fisher information which appears when multiple synchronized measurements are performed, and is the optimal scaling in the case of a finite coherence time.
Bibliographical noteFunding Information:
A.R. acknowledges the support of the Israel Science Foundation (Grant No. 1500/13), the support of the European commission (STReP EQUAM Grant Agreement No. 323714)), the EU Project DIADEMS, the Marie Curie Career Integration Grant (CIG) IonQuanSense (No. 321798), the Niedersachsen-Israeli Research Cooperation Program, and the DIP program (FO 703/2-1). This project has received funding from the European Union Horizon 2020 (Hyperdiamond).
© 2017 American Physical Society.