Fig. 6. Multi-electron phase-space characterization and control.

(A) Measured spectrogram for one-electron states (N = 1). (B) Measured spectrogram for two-electron states (N = 2). Black rectangles, regions of interest for our further analysis; white lines, artefacts from our detector system. (C) Measured electron arrival times for exactly one electron (black) and exactly two electrons per pulse (blue). (D) Measured pair density as a function of arrival times t₁ and t₂ for electrons 1 and 2 within a pair. Data are recorded at terahertz time delay of 1.1 ps. (E) Measured histogram of energy differences E₁-E₂ within a pair state after terahertz-driven energy magnification. The initial separation of ~2 eV (49, 50) becomes ~15 eV.