Quantum computation is the current high visibility fad in atomic physics.  Quantum computing is the latest way that physicists can get the government to fund their existence.

These computers operate along the same lines as normal computers but every quantum bit (qubit) is both a one and zero at the same time.  This sentence implies that quantum computers work. (1)

Only when the final result is desired do we measure the qubit state and receive either a one or a zero.  See (1)

The mathematical operations performed by a quantum computer alter the probability of receiving a one or a zero.  See (1)

The advantage is that quantum computers can potentially perform certain types of calculations much faster than classical computers (database searches and factoring large numbers are examples).  See (1). Potentially means they almost work. They almost work means they don’t work. (This is the first indication of the contradiction to come.)

The problem is that quantum computers rely on creating and controlling entangled quantum states, which are highly delicate beasts.  Here we find the excuse why quantum computing doesn’t work.

All excuses for the inefficiency of quantum computers are vague and inadequate because the real reason why they don’t work is never approached. The real reason would significantly decrease funding of quantum computing research.

The traditional approach to this has been to carefully control the interactions between qubits on a pair-wise basis (e.g., only two qubits can interact at a time).  The typical method of getting funding is to do something, then show with a lot of mathematics that what you did works, or, in this case, it works TO SOME EXTENT. The some extent is not much, in fact, not at all, but that is beside the point…?!

Every time you switch the interaction between two qubits on or off you run the risk of destroying that which you are trying to control, thus you can't do many computations in a row.  Another excuse for why quantum computing doesn’t work. This one, like the majority of them, implies that the reason is something that might be overcome in the future.

Not only that but you have lost much of the parallelism for which you are doing a quantum computation in the first place. Fluff. A major ingredient. One good piece of fluff and everyone will have something they can understand.

Now a new approach to the problem is under development.  The usual inclusion in any article on quantum computing is a hope that great magical scientists are coming close to overcoming the talked-about problems that stand in the way of practical solutions to the problems of quantum computing. Too bad the talked-about problems are not the real ones, and too bad magical scientists are as real as the magic they refer to.

The operations between qubits are still carefully controlled (otherwise no computation would be possible) but the interactions between qubits are not switched on and off, instead they are always on.  The contradiction. An interaction is an event with a beginning and end. Therefore, an interaction cannot be continuous. However, an interaction can continue for some time, can’t it? The answer to this question lies in the definition of interaction. Interactions in physics are mediated by one of four forces. This intermediation is instantaneous. Therefore, continuous interactions are impossible. CONTRADICTION.

If this were a mathematics discussion, then the speaker would be invited to resume sitting.

In case you are still here, this is the rest:

By developing a method by which quantum calculations can be performed even when an operation on one qubit effects all the remaining qubits has numerous advantages.  The dream. The impossible dream. “To dream the impossible dream….” Perhaps this is the American dream—to do something impossible.

The biggest fundamental advantage is that the implementation of many common algorithms can be simplified.  How wonderful it would be if something impossible could be achieved.

More practically, this method allows experimental physicists to start using coupled systems such as quantum dots, which have a much better chance of leading to practical computers that can actually scale to the point where they are useful. Ah, it’s not so impossible, here’s something that is less impossible (but still impossible) that has a better chance of succeeding (but, being impossible, it can never succeed.)

One of the distinguishing concepts is that any successful implementation of this algorithm is automatically a programmable multi-bit core much like the processing units of early microprocessors.  (This is all quite simple, really, and it has even been done before.)

The big question is can we build it?  The bigger answer is, “No”

Well that is a definite maybe, building quantum dots that are coupled together is now a fairly common lab practice.  (but we can get funding because the government is a buncha fools, and we’re smart; we can take advantage of them.)

The problem is that these dots are also coupled to the rest of the substrate so the carefully constructed quantum states are easily destroyed by the very material they are built upon.  It’s difficult, and only I can do it.

Isn’t it sad?

We are so close to doing something considered impossible, just like in the old days when Christopher Columbus sailed to America .

Everyone who doesn’t think the impossible is possible is just a fuddy-duddy. “You just lack the mathematics to understand.”

Yeah, right.

The Real Problem with Quantum Computing

One word: Photons.

(Photons are quintessential and very studied intermediary force particle-waves. Actually the following applies to all intermediary force particle-waves.)

Each photon travels both forward and backward in time.

For the photon, the event of arriving and the event of leaving happen simultaneously.

A human can have a clock and measure when a photon leaves and when it arrives.

A photon can have a clock, but it will never tick so all events happen at the same time for a photon.

A complication is that the path of a photon can be altered by a force field (e.g. gravitational or electromagnetic.)

For the human, it will appear that something happened over a period of time for the photon. However, for the photon there were two events—leaving and arriving, and both always happen at the same time.

The problem started with Niels Bohr. He introduced the idea of photons traveling as waves and the waves collapsing to particles at the moment of arrival. The idea was buried when Alain Aspect et al. performed the third of the famous three Aspect Experiments. That experiment demonstrated that a photon behaves both as a particle and as a wave at the same time. There is no collapse of any wave function. There is no point of time when the photon exists in any partial state. The photon arrives at the same time it leaves.

In the case of another quantum theoretical particle, once you stop touching the particle it exists in a particular state and will remain in that state unless you touch it again.

Quantum theory has eluded many people because they are unwilling to accept that their understanding based on objects perceivable by mere senses can not be used to relate to quantum theoretical objects.

Finally, and most importantly, without experimental evidence which confirms the conjectures or hypotheses dealing with quantum computing, the ideas of quantum computing can not be taken as fact.

Experimental evidence must be peer reviewed and repeated.