COMMENTS ON THE DIVINCENZO'S CRITERIA FOR QUANTUM COMPUTING

Let's comment briefly on the DiVincenzo's criteria for quantum computing. They are relatively old, published in 1996, and most are irrelevant.

1) A scalable physical system with well-characterized qubits.

Well-characterized qubits do not exist; there are always problems with qubits. A scalable quantum computer is highly elusive. So far, the number of qubits is somewhere between 59, or so, and several thousand, depending on the approach. A substantial number would be more than 10 million, but this is even beyond the realm of dreams. Nobody came up with a method of connecting a large number of qubits.

2) The ability to initialize the state of the qubits to a simple fiducial state, such as |000⋯⟩.

Any quantum system, which includes qubits, cannot be initialized to the same state in a reproducible way. Qubits and quantum gates are probabilistic, that's why. You can verify this by running my algorithm:

x = 0

Determine x

Repeat the first two steps a large number of times, say 1000-10000 times.

Plot the distribution of collected data. If the distribution is wide, the qubit is useless. This is the end of quantum computing!

A laptop can generate an extremely narrow distribution, but the qubit can never match that.

3) A "universal" set of quantum gates.

Quantum gates are probabilistic and will always return random data. Essentially, useful quantum gates cannot exist. The gate approach in quantum computing is totally bogus. All quantum gates with "big" names attached to them are just a bunch of baloney.

4) Long relevant decoherence times, much longer than the gate-operation time.

It would be nice to run a quantum computer without the necessity of rebooting it repeatedly to add two numbers. But this is beyond reach. Nobody came up with a solution to that problem.

5) A qubit-specific measurement capability.

The quantum state of any real quantum system cannot be determined. I came up with that law; it's fundamental to quantum mechanics. All quantum systems are probabilistic. This generates quantum noise that is a function of time. A wavefunction of any such system will always be in superposition with noise. Therefore, one cannot know what a quantum system is doing. This is valid for a single electron, photon, etc, or any small number of particles. Neutral atoms and ions exhibit similar behavior. It is not valid once the number of particles increases. That's why binary computers work, and quantum computers do not. There is no solution to this problem.

Quantum error correction is just a bad joke; some Russian half-brain from Caltech came up with that nonsense, so ignore it.

The probability of a single particle between a very low energy and an infinite energy is continuous. One can never reach the upper side. Therefore, a quantum qubit/gate can never represent integers, because integers have a probability of one.

More info on the subject (click here).

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