Directional loss of contrast by dephasing in temporal double-slit interferometry

Abstract

Attosecond streaking camera is an ex situ technique in which a linearly polarized (LP) XUV attopulse produces an electron wavepacket by photoionization in the presence of an IR femtopulse. By moving the two synchronous oppositely circularly polarized XUV pulses (that make the ionizing LP pulse) apart in time, we propose an attosecond double-slit streak camera scheme to see information loss in polarization-dependent two-slit phenomena. Such streaking interferogram is then composed of several Feynman's thought experiments in time domain, in which electrons are affected by the IR pulse as they exit the two attoslits upon XUV ionization processes to form Archimedean spiral patterns. As a proof-of-principle, when the IR femtofield and first XUV attopulse are synchronous, a loss of contrast through dephasing is seen in the simulated momentum and energy distributions of the photoelectron. It is shown that the contrast between bright and dark interference fringes diminishes predominantly along the IR-field polarization axis and is sensitive to the IR-field waveform. Our which-time information scheme provides further confirmation of the wave-particle duality.

Figures (4)

• Figure 1: A Feynman thought experiment scheme on an attosecond timescale. One or two noninvasive IR light is or are placed at the locations of the two slits, where a pair of time-delayed XUV pulses create a pair of electrons (see the shaded lumps) upon ionization. (a) Excellent contrast between bright and dark interference fringes is seen in the PED in the absence of IR fields. Partial (b) and total (c) loss of contrast are depicted when the IR fields are turned on.
• Figure 2: Effects of infrared light on electrons as they exit the temporal two slits to form Archimedean spirals through Ramsey interference: PMDs in the polarization plane for photoionization of He atoms produced in the absence (a) or presence of one [(b)-(c)] and two (d) IR fields. The single-cycle gaussian IR field has a wavelength $\lambda_{\text{IR}}=800$ nm, an intensity $I_{0,\text{IR}}=1$ TW/cm$^2$, and various CEP values: (b) $\phi_{\text{IR}1}=0$, (c) $\phi_{\text{IR}1}=\pi/2$, and (d) $\phi_{\text{IR}1}=\pi/2$, $\phi_{\text{IR}2}=3\pi/2$. The time-dependent electric fields of the $x$-component of the XUV pulses and IR fields for various waveform schemes are shown in SM.
• Figure 3: Visualization of the loss of contrast in a PED. [(a),(c)] forward emission ($\varphi=0$) and [(b),(d)] orthogonal emission ($\varphi=\pi/2$) in the polarization plane ($\theta=0$) in the case of one IR field with a CEP of $\pi/2$ (top) and two IR fields with CEPs of $\pi/2,3\pi/2$ (bottom). In each panel, results for no IR field is shown in red dashed curves for comparison.
• Figure 4: Ionization channels populated by two CRCP XUV pulses in the (a) absence or (b,c,d) presence of IR field. Results in (b) and (c) are for one IR field with a CEP of $0$ and $\pi/2$; results in (d) are for two IR fields of CEPs of $\pi/2,3\pi/2$.