Pacemaker for Schrödinger's cat
Scientists from the University of California, Berkeley, managed to conduct an experiment that allows you to say whether the notorious cat is alive or not.
Briefly recall that this is an exotic animal and how it relates to IT. Erwin Schrödinger put the following thought experiment:
Such a "vagueness", in theory, is the basis of quantum computing - thanks to it, calculations on quantum computers (QC) are performed using quantum bits (qubits), which simultaneously store 0 and 1, taking a certain value only "under the microscope", that is, direct measurement. It is the latter feature that is a stumbling block for the construction of QC, because any planned intervention will be regarded by the system as a measurement, which, in turn, will lead to errors in the calculations.
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R. Vijay, the head of the research group, states that they managed to “open the box with the cat.” The idea of ​​the experiment is to measure the state of zero or one indirectly - as if we were opening the box and looking there with one eye, and also squeezing our eyes tight.
Scientists have created a small superconducting chain (which is usually used as a qubit in prototypes of quantum computers) and launched, so far as we can say, a superposition of states 0 and 1, as a result of which the qubit cyclically changed the set of states. After that, the frequency of these oscillations was measured, which makes it possible to indirectly indicate the state of the system at a certain point in time, without forcing it to choose whether it is zero or one.
Despite all the theoretical elegance of the experiment, which made it possible not to destroy the quantum superposition, everything turned out to be not so simple - when measuring, the system spontaneously changed the oscillation frequency, which could not be predicted. Scientists were able to circumvent this problem due to the fact that the measurements were carried out fast enough to introduce the opposite perturbation, equal in magnitude but reversed in direction, returning the system to the oscillation frequency without external interference. In fact, this is the principle of the pacemaker - with a deviation of the heart rate from the correct one, the device sends a pulse that corrects the work of the “flame engine”.
The idea itself is not new, but previous researchers did not come to success: compensations that did not violate the superposition were too weak to register, and large ones made noise in the system.
The results are not perfect yet, but they exist - the qubit existed in the necessary state for microseconds - this is a whole eternity for such experiments, and can be enough for use in calculations.
According to the team leader, this is a big step for error control in quantum computing. Well, wait and see.
PS This is an adapted translation of this article , unfortunately, I don’t have enough karma for the post in the “Translations” section or in “Popular Science”, I chose the most related topic I can post.
Briefly recall that this is an exotic animal and how it relates to IT. Erwin Schrödinger put the following thought experiment:
A cat is locked in a steel chamber with the next hellish machine (which must be protected from the cat’s direct intervention): inside the Geiger counter there is a tiny amount of radioactive substance, so small that only one atom can decay within an hour, but with the same probability and do not disintegrate; if this happens, the reading tube is discharged and a relay is triggered, lowering the hammer that breaks the cone with hydrocyanic acid. If for an hour all this system is provided to itself, then we can say that the cat will be alive after this time, as soon as the atom does not collapse. The very first decay of an atom would poison the cat. The psi-function of the system as a whole will express it, mixing in itself or smearing a live and dead cat (sorry for the expression) in equal shares.
Typical in such cases is that the uncertainty, initially limited to the atomic world, is transformed into macroscopic uncertainty, which can be eliminated by direct observation. This prevents us to naively accept the “blur model” as a reflective reality. In itself, this does not mean anything unclear or contradictory. There is a difference between a fuzzy or defocused photo and a snapshot of clouds or fog.
Such a "vagueness", in theory, is the basis of quantum computing - thanks to it, calculations on quantum computers (QC) are performed using quantum bits (qubits), which simultaneously store 0 and 1, taking a certain value only "under the microscope", that is, direct measurement. It is the latter feature that is a stumbling block for the construction of QC, because any planned intervention will be regarded by the system as a measurement, which, in turn, will lead to errors in the calculations.
')
R. Vijay, the head of the research group, states that they managed to “open the box with the cat.” The idea of ​​the experiment is to measure the state of zero or one indirectly - as if we were opening the box and looking there with one eye, and also squeezing our eyes tight.
Scientists have created a small superconducting chain (which is usually used as a qubit in prototypes of quantum computers) and launched, so far as we can say, a superposition of states 0 and 1, as a result of which the qubit cyclically changed the set of states. After that, the frequency of these oscillations was measured, which makes it possible to indirectly indicate the state of the system at a certain point in time, without forcing it to choose whether it is zero or one.
Despite all the theoretical elegance of the experiment, which made it possible not to destroy the quantum superposition, everything turned out to be not so simple - when measuring, the system spontaneously changed the oscillation frequency, which could not be predicted. Scientists were able to circumvent this problem due to the fact that the measurements were carried out fast enough to introduce the opposite perturbation, equal in magnitude but reversed in direction, returning the system to the oscillation frequency without external interference. In fact, this is the principle of the pacemaker - with a deviation of the heart rate from the correct one, the device sends a pulse that corrects the work of the “flame engine”.
The idea itself is not new, but previous researchers did not come to success: compensations that did not violate the superposition were too weak to register, and large ones made noise in the system.
The results are not perfect yet, but they exist - the qubit existed in the necessary state for microseconds - this is a whole eternity for such experiments, and can be enough for use in calculations.
According to the team leader, this is a big step for error control in quantum computing. Well, wait and see.
PS This is an adapted translation of this article , unfortunately, I don’t have enough karma for the post in the “Translations” section or in “Popular Science”, I chose the most related topic I can post.
Source: https://habr.com/ru/post/153509/
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