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).
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).