Monitoring Spontaneous Charge-Density Fluctuations by Single-Molecule Diffraction of Quantum Light.
- Author(s): Dorfman, Konstantin E
- Asban, Shahaf
- Ye, Lyuzhou
- Rouxel, Jérémy R
- Cho, Daeheum
- Mukamel, Shaul
- et al.
Published Web Locationhttps://doi.org/10.1021/acs.jpclett.9b00071
Homodyne X-ray diffraction signals produced by classical light and classical detectors are given by the modulus square of the charge density in momentum space |σ(q)|2, missing its phase, which is required in order to invert the signal to real space. We show that quantum detection of the radiation field yields a linear diffraction pattern that reveals σ(q) itself, including the phase. We further show that repeated diffraction measurements with variable delays constitute a novel multidimensional measure of spontaneous charge-density fluctuations. Classical diffraction, in contrast, only reveals a subclass of even-order correlation functions. Simulations of two-dimensional signals obtained by two diffraction events are presented for the amino acid cysteine.