I was wondering: Would something like this be expected to have any kind of visible effect?

(Their object is at the limit of bare-eye visibility in favorable lighting,* but suppose that they can expand their results by a couple orders of magnitude.)

From “first principles” I’d expect that the light needed to actually look at the thing would collapse the superposition (in the sense of first entangling the viewer with the object, so as to perceive a single version of it in every branch, and then with the rest of the universe, so each world-branch would contain just a “classical” observation).

But then again one can see interference patterns with diffracted laser light, and I’m confused about the distinction.

[eta:] For example, would coherent light excite the object enough to break the superposition, or can it be used to exhibit, say, different diffraction patterns when diffracted on different superpositions of the object?

[eta2:] Another example: it the object’s wave-function has zero amplitude over a large enough volume, you should be able to shine light through that volume just as through empty space (or even send another barely-macroscopic object through). I can’t think of any configuration where this distinguishes between the superposition and simply the object being (classically) somewhere else, though; does anyone?

(IIRC, their resonator’s size was cited as “about a billion atoms”, which turns out as a cube with .02µm sides for silicon; when bright light is shined at a happy angle, depending on the background, and especially if the thing is not cubical, you might just barely see it as a tiny speck. With an optical microscope (not bare-eyes, but still more intuitive than a computer screen) you might even make out its approximate shape. I used to play with an atomic-force microscope in college: the cantilever was about 50µm, and I could see it with ease; I don’t remember ever having seen the tip itself, which was about the scale we’re talking about, but it might have been just barely possible with better viewing conditions.)