Research ArticleQuantum Mechanics

In search of multipath interference using large molecules

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Science Advances  11 Aug 2017:
Vol. 3, no. 8, e1602478
DOI: 10.1126/sciadv.1602478
  • Fig. 1 Experimental setup.

    (A) Focused laser source produces a thermal beam of PcH2 molecules, which diffracts at a vertical array of single, double, and triple slits, which are aligned to the local gravitation field g, before landing on a thin quartz detection screen. The deposited molecules are observed using high-resolution fluorescence imaging. (B) Schematic of the triple slit. The openings (black) have a transverse width a = 80 nm, and their centers are separated by a distance d = 100 nm.

  • Fig. 2 Diffraction mask.

    TEM image of a part of the M4 submask of the triple slit. The openings in the mask (white) are a = 80 nm wide and have a period of d = 100 nm.

  • Fig. 3 Molecule diffraction patterns.

    Fluorescence images of molecules after diffraction at (A) a single slit, (B) a double slit with period 2d, (C) a double slit with period d, and (D) a triple slit with period d. Slower molecules fall further under gravity in the time it takes them to reach the screen. This results in a larger separation between diffraction orders further down the screen. All images are aligned vertically with respect to gravity. In (D), we have highlighted the center of the m = 0 fringe. (E) Sorkin parameter ε(x, λdB) for the interference patterns (A to D) calculated in accordance with Eq. 5.

  • Fig. 4 Bounding multipath interference.

    (A) Normalized Sorkin parameter κ(x, λdB). (B) κ(0, λdB), the normalized Sorkin parameter as a function of de Broglie wavelength at the center of the m = 0 interference fringe. (C) κ(x, 3.5 pm), the normalized Sorkin parameter as a function of transverse position on the detection screen for a mean de Broglie wavelength of 3.5 pm. Each figure shows the average over five different experimental runs. In (B) and (C), black lines show the mean, whereas shaded gray areas enclose the 1σ SE. The spatial resolution in all figures is limited by the point-spread function of the imaging system, which is 1.6 μm, approximately four pixels in the plane of the molecular detection screen.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/8/e1602478/DC1

    Diffraction mask

    Molecule detection

    Interference patterns

    fig. S1. TEM images of the four submasks.

    fig. S2. Intensity distribution of the 661-nm illumination light.

    fig. S3. Surface migration of PcH2 molecules behind a grating with a period of 2 μm.

    fig. S4. Molecule number as a function of detector position.

    fig. S5. Raw data before dark count subtraction.

    fig. S6. Determining molecular velocities from fringe spacing.

    fig. S7. Reconstructing molecular velocity distributions.

  • Supplementary Materials

    This PDF file includes:

    • Diffraction mask
    • Molecule detection
    • Interference patterns
    • fig. S1. TEM images of the four submasks.
    • fig. S2. Intensity distribution of the 661-nm illumination light.
    • fig. S3. Surface migration of PcH2 molecules behind a grating with a period of 2 μm.
    • fig. S4. Molecule number as a function of detector position.
    • fig. S5. Raw data before dark count subtraction.
    • fig. S6. Determining molecular velocities from fringe spacing.
    • fig. S7. Reconstructing molecular velocity distributions.

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