Move through three gratings of light. Then build a detector signal one illustrative count at a time, while asking what the stripes can really tell us.
THE APPARATUS / TALBOT–LAU INTERFEROMETER
A shadow has a rival explanation.
The actual measurement was transmitted cluster counts as the third standing-light grating moved sideways. A fringe signal can arise from more than one mechanism; changing the central grating’s power helps distinguish the quantum model from classical moiré shadows.
G1G2G3DETECTOR
INNER WORLD / 07 THREE LIGHT GRATINGS · SCHEMATIC
G1 / PREPARE COHERENCE
Select a research file. Drag to rotate the model; pinch or use the zoom buttons.
FILE 01 / MATTER & QUANTUM
One cluster, thousands of atoms
SODIUM CLUSTERS / MASS-SELECTED BEAM
How large a piece of matter can still show wave behavior?
The Vienna team sent cold sodium clusters through a near-field interferometer. Some clusters contained more than 7,000 atoms and exceeded 170,000 atomic mass units. Their large size is the point of the test: the entire cluster must be treated as one quantum object in the model, rather than thousands of independent atomic waves.
Here a small glow marks the beam only to orient you in the apparatus. It is not a filmed cluster, a calculated path, or a claim that a cluster literally follows one glowing line through all three gratings.
Three ultraviolet standing-light gratings play different roles. G1 prepares transverse coherence by spatial filtering. G2 changes the wave phase and also removes some clusters. G3 selects which part of the resulting pattern passes onward to the detector. The three bright planes in the model are a schematic visual cue: their spacing, beam width, and stripe sizes are not to scale.
This is a Talbot–Lau near-field arrangement, not an ordinary two-slit experiment. Its behavior depends on diffraction, absorption, grating separation, cluster properties, and how the standing-light fields interact with the beam.
The team moved G3 transversely and counted clusters that made it through at each grating position. Remaining neutral clusters were photoionized for mass-selective detection. Each illustrative count dot in the interactive scan below means one transmitted count at the current G3 setting. It is not an x-y impact location on a screen.
Try the scan. The plotted points are total counts versus G3 displacement. The teaching pattern uses an idealized 10% fringe visibility to illustrate the scale of a reported result, but its event order and counts were generated for this page and are not the published measurements.
Does a stripe pattern by itself prove quantum interference?
No. A set of three gratings can produce a classical moiré shadow pattern too. Counting peaks and troughs at G3 is not enough to distinguish that alternative. The experiment therefore changed the central grating’s light power and compared how the signal contrast responded against quantum and classical predictions.
The paper reports a fringe visibility of 0.10 ± 0.01 in one of its large-cluster measurements. That numerical value is the inspiration for the idealized display below; the model does not reconstruct the paper’s measured points or its complete quantum and classical contrast curves. Open the Evidence File for the claim, competing account, and remaining questions.
At each position of G3, a detector counts clusters that pass through. Watch the totals accumulate, then compare neighboring settings. The chart uses synthetic, idealized counts with approximately 10% fringe visibility; it is not recorded experiment data.
G3 POSITION —THIS POSITION 0TOTAL COUNTS 0
PRESS START SCAN TO BUILD THE SIGNAL
Vertical axis: illustrative counts per position, starting at zero. Each small dot is one synthetic count, stacked under its G3 setting for display. Horizontal axis: one schematic grating period, not measured displacement values.
Ready. Start the teaching scan or reveal its completed pattern.
WHAT YOU SEE
Counts, not screen impacts.
Each small dot represents one illustrative transmitted count at the current G3 position. Dots stack upward as a tally; their height is a count, not a particle landing position. The real experiment registered detected clusters as G3 scanned. The diagram does not assign x-y landing points to individual clusters.
WHAT IT DOES NOT SETTLE
Stripes need a comparison.
A classical moiré pattern can also make stripes. The study compared how contrast changed with G2 light power against quantum and classical models; this teaching scan does not reproduce that test.
The interferometer counts transmitted clusters. Compare that measurement with a collider’s reconstruction of charged tracks, electromagnetic showers, and hadron jets.
The 3D planes depict the roles of G1, G2, and G3, and the scan illustrates a count rate at successive G3 settings. Light-stripe thickness, grating and detector spacing, luminous beam, timing, synthetic counts, and the 10% teaching curve are illustrative. The published study used three ultraviolet standing-light gratings, a mass-selective detector after photoionization, and power-dependent comparisons to test quantum and classical accounts. This page does not render measured event records or the paper’s quantum calculations.
Synthetic detections teach the analysis; they do not repeat the experiment.
The accumulating counts illustrate how a pattern becomes recognizable. They are generated for this teaching view and are not additional measurements of 7,000-atom clusters. Follow the investigation to compare the actual evidence and the predictions used to interpret it.
Ask yourself Can the analysis be checked, and has another study tested the claim with additional evidence?
THE SIGNAL CONTINUES
Some discoveries stay with you.
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