Because it’s not known how to do so, in general. And it amounts to manipulating qubits.

We can't do , because classical computer use bits, were Quantum computers use qubits , this qubits use Quantum superposition.

In theory, it should be possible. There are a few difficulties I see though. In Schrodinger's Cat, a single qbit is generated, representing the binary state of whether a cat is dead or not. One qbit isn't enough to do anything significant. If the condition is not binary, and time is provided over which more nuclear decay events could occur, more qbits could be created. Note that in this case, the qbits are extremely abstract, but they are no less valid, as seen with Schrodinger's Cat. As long as the state of the computer is not observed, and the calculations being done are dependent on the randomness of the decay, more and more qbits could be collected over time, as long as the machine has the resources to handle the state generated by the quantum events.

There's another problem though, and this might be far more serious: How are the results communicated with the world outside the box, without collapsing the probability function by revealing the internal state? You now have a computer system with some sort of feature that collects quantum randomness to create many state super positions, allowing it to effectively calculate things using a sort of quantum parallelization created by what are basically abstract qbits, but you can't show an observer any one of the results without wiping out all of the other results, because displaying a result necessarily collapses the probability function. And further, you don't get to choose what result is communicated, because when the probability function collapses, the state it ultimately lands on is completely random.

That said, I don't actually know how this particular limitation is worked around for quantum computers, so maybe there is a solution. Like I said at the beginning, in theory, it should be possible. If the difficulties can be worked out, maybe this would be a cheaper option for quantum computing. I just can't see how one would work around the issue of communicating the final observation without erasing all but one randomly selected result.

Benjamin Williams Thank you Sir for your detailed answer. Please don't mind if I reply to your answer a little later, because, I would like to ponder about it before writing a reply.

Thank you and best regrads,

N. Gurappa.

Benjamin Williams Sir I broadly or may completely agree with your analysis. Once, all classical bits in a computer behave as qubits, then essentially, it's the kind of quantum programming which matters to solve any given problem.

My point is that only one radioactive atom, with half-life of one hour, is enclosed along with a classical computer inside a box. The decay product has some definite non-zero probability to hit every classical bit though at the end of the day it will hit anyone only and hence, they all enter into a superposition of |0> and |1> states, i.e., they all behave like qubits. Moreover, there is no need to worry about the decoherence, because, until the box is opened, the superpositions persist.

Therefore, the programming must be done such that it should make use of the quantumness of Schrodinger's cat-qubits either to create interference or entanglement among the desired qubits or both so that the final solution to a given problem is obtained the moment the box is opened.

Looking forward for your kind response,

With best regards,

N. Gurappa.

There are very different between Classic Computers and Quantom-Base Computers such Such as architecture of Hardware and software, Process technology, Data Stream, Memory Structure, Methods and Alghorithms that usage in process, thus for answer this question indispensable submit a scientific paper.

I'm not convinced a single nuclear decay event would be sufficient. The problem here is bias, and it's a fundamental problem with using qbits generated through nuclear decay. If the nuclear decay can flip a bit by hitting, say, a memory component, yes, there should be some kind of superposition as soon as the box is closed, but because the odds of it hitting that specific bit are close to nothing, your probability function is incredibly heavily biased in favor of one outcome and not the other.

Another issue is that each qbit produced must be used in the program, or it doesn't matter. So, let's say you have 64GB of ram, but your program only uses 1GB. You've further cut your probability of a relevant bit getting flipped by a factor of 1/64, increasing the bias even further.

The big issue though, is what happens when you open the box. You won't get the results of a bunch of parallel quantum computations. You'll get one of the many possible outcomes, determined at random, and affected by the bias. If the bias is extremely heavily in favor of no relevant bits getting flipped, that's probably the outcome you get when you open the box. The most fundamental problem here is that even though it is theoretically possible to do quantum computing this way, as soon as you observe the result, the probability function collapses down to only a classical outcome.

So the problem here isn't one of different hardware, theoretical limitations to the process, or anything else inherent to the function. The problem is maintaining the superposition long enough to get all of the results and not just one possible outcome.

I suspect this is why quantum computing is so difficult. Maybe the problem is entanglement of qbits. In your cat box, all qbits produced are entangled. When the box is opened and the system is observed, the entanglement is broken, collapsing all of the qbits. What if, however, the qbits weren't intangled? In that case, it becomes possible to measure the state of one qbit without collapsing the rest of them. I'm not a quantum computing expert, so I'm not sure if this is how quantum computing solves the collapse problem, but based on my knowledge of quantum physics in general, this makes a sort of intuitive sense to me.

Anyhow, in summary: I think bias is a problem that would have to be resolved to get good results, and Schrodinger's Cat has large bias that changes over time, which would apply here as well. The big problem, however, is that the probability function for the entire system collapses upon observation, instantly reducing the solution to a classical one, before the quantum solution can be observed. I'm not sure there is a way around the collapse problem in this scenario.

Benjamin Williams Dear Sir,

I totally agree with your intuitive argument. But that’s not actually how quantum computers are expected to work!

Instead of a single radioactive atom, let’s consider particle, whose spin is initially prepared in |y;up> state. When this |y;up> state passes through a Stern-Gerlach apparatus having the magnetic field along the z-direction, then it becomes a superposition of |z;up> and |z;down> states. One can place a classical computer such that the |z;up> state is encountered by the classical bits in the classical computer. Each classical bit has some non-zero probability to be encountered by the |z;up> state. If the particle in |z;up> state hits a classical bit, then it gets changed from |0> to |1>. Unlike the radioactive atom, we can control when to release the particle in |y;up> state.

According to quantum mechanics, a single |y;up> state is sufficient to put all classical bits into quantum superpositions of |0>’s and |1>’s. Upon observation only the state collapses onto a particular classical bit flipping it to |1> from |0>. But before the observation, i.e., before opening the box, all classical bits are in quantum superposition behaving like qubits and all quantum computation must be done before opening the box only so that the final answer must be revealed upon opening the box. Interestingly, it's upto us to decide when to open the box and until then, the quantum superposition remains unaffected!!!

< The big problem, however, is that the probability function for the entire system collapses upon observation, instantly reducing the solution to a classical one, before the quantum solution can be observed. I'm not sure there is a way around the collapse problem in this scenario.> This is the case with all quantum systems and even the traditional quantum computers are not an exception to this.

Thank you and best regards,

N. Gurappa.

Mr. Gurappa, in your first bullet, you define the bit to be classical, but then in the third sentence, you switch to (implicitly) defining it as a qubit. You haven't shown that a bit changes to a qubit, but merely asserted that it does.

However, the language you use in the second bullet opens the door to understanding why the functionality of so called "quantum superposition" can indeed, in fact easily, be achieved by classical bits. The key realization is to understand that if your classical computer represents entities, e.g., states of the world, e.g., the state of the world where the cat is alive, or the state where the cat is dead, by sets of classical bits, rather than by single bits, then the physical representations of multiple states of the world can simultaneously be active in physical, and classical, superposition. This is simply because sets can intersect. Suppose the overall computer memory consists of 1 million classical bits. And suppose we define that all world states will be represented by sets of the same cardinality, say 1,000. So, world state A (cat alive) is represented by one particular set, S(A), of 1,000 bits and state B (cat dead) by some other set, S(B) of 1,000 bits. Suppose S(A) and S(B) have 500 bits in common. Then, clearly, when S(A) is fully active, i.e., all 1,000 of its bits are on, S(B) is 50% active, i.e., 500 of S(B)'s bits are active. Both representations are simultaneously physically active, S(A) at 100%, and S(B) at 50%. We could consider these degrees of activity to represent the likelihoods of those states. Although this example involves only two states, the same principle holds no matter how many states are represented in the memory. That is, whenever, any one state is fully active, the representations of all states stored in the memory, will simultaneously be physically active in proportion to their intersections with the single fully active representation.

With respect to the language you use in your second bullet, it's not that each classical bit of the memory is individually functioning as a qubit, but rather that the 1,000 bits as a whole are collectively functioning as an "N-trit", where N states have been stored in the memory.

We can imagine an output path (a giant matrix of connections leading from the 1 million bits that comprise the memory) into a max operation that decides that the state with the max number of active bits (i.e., the most likely state) is in fact the actual state. That's how we could model "collapse of the superposition". However, there is nothing preventing there from being another giant matrix, this one, a recurrent matrix, that completely connects the 1 million bits to itself (in this case, there would 10^12 connections). In this case, we could imagine that a propagation of signals via the recurrent matrix takes the current active state, i.e., at time T, into the next state, at T+1. This would allow the current state, which, by the superposition property of sets, represents one likelihood distribution over all states (with varying degrees of likelihood), to be transformed into (evolve to) a next state, which could be some entirely different likelihood distribution over all states.

So one matrix could allow for (explain) collapse of the superposition and the other (the recurrent matrix) could allow for the continual evolution of the system without going through collapse, i.e., the two update operations described by Everett, providing a straightforward, in fact, simple, resolution of what is called the "measurement problem".

I've described this view many times for some years now, e.g., "The classical realization of quantum parallelism" (http://brainworkshow.sparsey.com/the-classical-realization-of-quantum-parallelism/), "A Physical theory based on sets, not vectors: Part 1" (http://brainworkshow.sparsey.com/a-physical-theory-based-on-sets-not-vectors/), "Not Copenhagen, not Everett, a new interpretation of quantum reality" (http://brainworkshow.sparsey.com/not-copenhagen-not-everett-a-new-interpretation-of-quantum-reality/), but been unable to get any recognized expert on quantum physics/computation to provide a serious critique. As I explain in the referenced essays, the change from viewing entities, either the representations of physical states (as in the case of quantum computation) or the physical states themselves (as in quantum physics), as sets rather than vectors, constitutes a massive paradigm shift from the 100-yr old mainstream quantum theory, which from day one, has been fully vested in formalizing states as vectors (i.e. tensors in a Hilbert space).

Sincerely,

Rod Rinkus

Quantom devices have deep different with classic device on infrastructure, logic, data flow and process mekanisms.

Classical computers are big objects. The quantum superposition of states of an object is realizable if the objects are microscopic. Schrodinger's cat is the typical example of impossibility of superposition of states of a macroscopic object.

Sofia D. Wechsler

Dear Prof. Sofia D. Wechsler,

Thank you for your kind answer. Though I agree with < Schrodinger's cat is the typical example of impossibility of superposition of states of a macroscopic object.>, but there are a few points I would like to point out:

1. What do I mean by my question is not putting the entire classical computer in quantum superposition similar to Schrödinger’s cat, but putting each and every classical-bit into quantum superposition analogous to Schrödinger’s cat. Putting entire classical computer into quantum superposition a la Schrödinger’s cat may be useless for the purpose of quantum computation.

2. < Classical computers are big objects> Even quantum computers are not small in their size, but looks bigger than the classical ones.

3. < The quantum superposition of states of an object is realizable if the objects are microscopic.> But nowadays, some physicists are talking about the “superposition of blackholes”!!!

Thanks once again and best regards,

N. G

Dear N. Gurappa

It may be interesting for your question to see if states of "artificial atoms" can be put in quantum superposition. Such atoms can be brought to one state or another by inputting to them certain inputs. I read of such atoms in works of the team of prof. Savasta. If you are interested I invite you to tell me and I will try to find the article.

Best regards

Sofia D. Wechsler

Dear Prof. Sofia D. Wechsler,

Thank you for your kind reply.

Please send that article about artificial atoms.

With best regards,

N.G

Dear N. Gurappa

The article is

1) A Single Photon Can Simultaneously Excite Two or More Atoms,

arXiv:1601.00886v2 [quant-ph]

I also recommend:

2) Individually Addressable Artificial Atoms in Silicon Photonics.

arXiv:2202.02342 [quant-ph]

Good luck!

Dear N. Gurappa

Indeed, in the process described in the reference 1 (that I found as particularly interesting), there are states of the two artificial atoms in which these atoms are in a superposition of states. One can see in the diagrams in the figures 1, 2, and 4.

The artificial atoms are devices, i.e. not microscopic particles.

Good luck!

Sofia D. Wechsler

Dear Prof. Sofia D. Wechsler,

Thank you for the references sent and also for the info .

With best regards,

N.G

Please notice that in the 3rd point of my earlier reply, I wrote “superposition of blackholes”. But, it should be "blackhole in superposition".