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.)
Luboš Motl writes: “it’s hard to look at it while keeping the temperature at 20 nanokelvin—light is pretty warm.”
My quick impression of how this works:
You have a circuit with electrons flowing in it (picture). At one end of the circuit is a loop (Josephson junction) which sensitizes the electron wavefunctions to the presence of magnetic field lines passing through the loop. So they can be induced into superpositions—but they’re just electrons. At the other end of the circuit, there’s a place where the wire has a dangly hairpin-shaped bend in it. This is the resonator; it expands in response to voltage.
So we have a circuit in which a flux detector and a mechanical resonator are coupled. The events in the circuit are modulated at both ends—by passing flux through the detector and by beaming microwaves at the resonator. But the quantum measurements are taken only at the flux detector site. The resonator’s behavior is inferred indirectly, by its effects on the quantum states in the flux detector to which it is coupled.
The quantum states of the resonator are quantized oscillations (phonons). A classical oscillation consists of something moving back and forth between two extremes. In a quantum oscillation, you have a number of wave packets (peaks in the wavefunction) strung out between the two extremal positions; the higher the energy of the oscillation, the greater the number of peaks. Theoretically, such states are superpositions of every classical position between the two extremes. This discussion suggests how the appearance of classical oscillation emerges from the distribution of peaks.
So you should imagine that the little hairpin-bend part of the circuit is getting into superpositions like that, in which the elements of the superposition differ by the elongation of the hairpin; and then this is all coupled to electrons in the loop at the other end of the circuit.
I think this is all quite relevant for quantum biology (e.g. proteins in superposition), where you might expect to see a coupling between current (movement of electrons) and conformation (mechanical vibration).
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.)
Luboš Motl writes: “it’s hard to look at it while keeping the temperature at 20 nanokelvin—light is pretty warm.”
My quick impression of how this works:
You have a circuit with electrons flowing in it (picture). At one end of the circuit is a loop (Josephson junction) which sensitizes the electron wavefunctions to the presence of magnetic field lines passing through the loop. So they can be induced into superpositions—but they’re just electrons. At the other end of the circuit, there’s a place where the wire has a dangly hairpin-shaped bend in it. This is the resonator; it expands in response to voltage.
So we have a circuit in which a flux detector and a mechanical resonator are coupled. The events in the circuit are modulated at both ends—by passing flux through the detector and by beaming microwaves at the resonator. But the quantum measurements are taken only at the flux detector site. The resonator’s behavior is inferred indirectly, by its effects on the quantum states in the flux detector to which it is coupled.
The quantum states of the resonator are quantized oscillations (phonons). A classical oscillation consists of something moving back and forth between two extremes. In a quantum oscillation, you have a number of wave packets (peaks in the wavefunction) strung out between the two extremal positions; the higher the energy of the oscillation, the greater the number of peaks. Theoretically, such states are superpositions of every classical position between the two extremes. This discussion suggests how the appearance of classical oscillation emerges from the distribution of peaks.
So you should imagine that the little hairpin-bend part of the circuit is getting into superpositions like that, in which the elements of the superposition differ by the elongation of the hairpin; and then this is all coupled to electrons in the loop at the other end of the circuit.
I think this is all quite relevant for quantum biology (e.g. proteins in superposition), where you might expect to see a coupling between current (movement of electrons) and conformation (mechanical vibration).
Every source I’ve seen (e.g.) gives the resonator as flat, some tens of µm long, and containing ~a trillion atoms.
Duh, it would be exactly like the agents in The Matrix.