Sub-Attosecond Metrology via X-Ray Hong-Ou-Mandel Effect
arXiv:1908.01592
The paper proposes using Hong-Ou-Mandel interference of broadband x‑ray photon pairs generated by spontaneous parametric down‑conversion to measure sub‑attosecond time delays and sub‑Angstrom path differences with precision better than 0.1 attosecond.
Abstract
We show that sub-attosecond delays and sub-Angstrom optical path differences can be measured by using Hong-Ou-Mandel interference measurements with x-rays. We propose to use a system comprising a source based on spontaneous parametric down-conversion for the generation of broadband x-ray photon pairs and a multilayer-based interferometer. The correlation time of the photon pairs and the Hong-Ou-Mandel dip are shorter than 1 attosecond, hence the precision of the measurements is expected to be better than 0.1 attosecond. We anticipate that the scheme we describe in this work will lead to the development of various techniques of quantum measurements with ultra-high precision at x-ray wavelengths.