Phase estimation with weak measurement using a white light source

Ultra-sensitive phase estimation with white light

An improvement of the scheme by Brunner and Simon [Phys. Rev. Lett. 105, 010405 (2010)] is proposed in order to show that quantum weak measurements can provide a method to detect ultrasmall longitudinal phase shifts, even with white light. By performing an analysis in the frequency domain, we find that the amplification effect will work as long as the spectrum is large enough, irrespective of the behavior in the time domain. As such, the previous scheme can be notably simplified for experimental implementations.

Multiple phase estimation for arbitrary pure states under white noise

In any realistic quantum metrology scenarios, the ultimate precision in the estimation of parameters is limited not only by the so-called Heisenberg scaling, but also the environmental noise encountered by the underlying system. In the context of quantum estimation theory, it is of great significance to carefully evaluate the impact of a specific type of noise on the corresponding quantum Fisher information (QFI) or quantum Fisher information matrix (QFIM). Here we investigate the multiple phase estimation problem for a natural parametrization of arbitrary pure states under white noise. We obt…

Comment on White, Mutus, Dressel, et al., "Preserving entanglement during weak measurement ... " [arXiv:1504.02707]

In the cited paper [White, T., Mutus, J., Dressel, J. et al., "Preserving entanglement during weak measurement demonstrated with a violation of the Bell-Leggett-Garg inequality", npj Quantum Information 2, 15022 (2016), arXiv:1504.02707], experimental results were presented that clearly prove that the quantum entanglement between two qubits is preserved after weak enough measurements are performed on them. The theoretical interpretation of the reported results, however, requires further consideration. The remarks made in this paper may have serious implications both for quantum foundations and…

A comment on "Weak value amplification is suboptimal for estimation and detection"

By assuming that the weak value is real, Ferrie and Combes render their result inapplicable to weak measurement experiments which are aimed at enhancing precision.

Comment on "Weak value amplification is suboptimal for estimation and detection"

The assumptions of Ferrie and Combes are irrelevant for realistic experimental situations. This undermines their conclusions.

基本量子极限下的贝叶斯频率估计

Bayesian frequency estimation at the fundamental quantum limit

针对基础物理实验中未知频率弱信号搜寻受量子噪声限制、经典频率估计存在信噪比阈值的问题，提出量子白化协变测量相干协议，可超越经典正交测量，还可用于无先验的幺正编码参数感知。