How can a bit be simultaneously two different things and how can the computer tell which thing it needs for which process?
My mind is boggled
I’m not going to even attempt an explanation but, from what I’ve read, providing an comprehensible explanation to people with the necessary prerequisite knowledge is a challenge for those working in the field.
“Not only is the Universe stranger than we think, it is stranger than we can think.†- Werner Heisenberg
I’m not sure, but if I get one will it make me better at Fornite? Will pron come in extra high def? You are not asking the right questions.
Complete aside, but auto-correct wants to change Fornite to fornicate. Good substitute. Pron must be used enough it doesn’t suggest an alternative.
I could answer that in a way that you’d understand and in a way that you wouldn’t understand, but the ultimate result regarding your comprehension or non-comprehension will depend on whether you read the answer.
How can a bit be simultaneously two different things and how can the computer tell which thing it needs for which process?
My mind is boggled
Not really an precise analogy, but a classic computer is like a light switch, on or off.
A quantum computer is like a dimmer switch, it can be on or off or anything in between.
As for knowing how to build algorithms to solve problems, that is way above my head. That is the kind of stuff where you could overturn the world economy if you could solve those kinds of problems.
They use crystals instead of chips, something about stacking…
How can a bit be simultaneously two different things and how can the computer tell which thing it needs for which process?
My mind is boggled
Not really an precise analogy, but a classic computer is like a light switch, on or off.
A bit in a classical computer is like a light switch; it’s a crucial, but small part of a classical digital computer.
A quantum computer is like a dimmer switch, it can be on or off or anything in between.
The analog in a quantum computer is a qubit. It can be in a superposition of both on and off simultaneously. It can’t take on in-between values. (Interestingly, there are also “analog computers” where values can be other than 1 and 0. But, they are largely obsolete, and aren’t related to quantum computers.)
As for knowing how to build algorithms to solve problems, that is way above my head. That is the kind of stuff where you could overturn the world economy if you could solve those kinds of problems.
Most classical computers use a Von Neumann Architecture where bits are arranged into 8, 16,32, or 64-bit registers. “Memory” can be thought of as an array of registers. The Central Processing Unit executes a program stored in memory and writes it’s results elsewhere in memory.
The architecture of (most) Quantum Computers is different. You have an n-qubit register like a classical computer, but each bit can be put into a superposition of 1/0 simulataneously. Instead of a program running in memory and storing results there, you have a “score”, analogous to a musical score, that manipulates the q-register in a sequence of steps to carry out some algorithm like Grover’s Algorithm or Shor’s Alogorithm. After running the score, the result is left in the q-register.
Here’s a basic tutorial on QC:
If you want to get serious, here is an MIT Physics lecture on QC and related topics:
https://ocw.mit.edu/...e-videos/lecture-24/
EDITED to tweak links.
Shor’s algorithm is a particularly good one to dig into, as this hits directly at breaking current encryption techniques in polynomial time.
Essentially, given large enough quantum computers, this is the way they will trash a lot of the current security on the internet 
Shor’s algorithm is a great example of how QC is advantageous for certain specialized calculations. The cybersecurity ramifications are overblown IMO, though. Just doubling the number of bits in keys completely negates the potential speed up from Shor’s algorithm. If/when QC gets there, it should be pretty straightforward to evolve the crypto-standards to use the longer keys.
Interestingly, if we are ever able to build a 300+ qubit QC, that would be strong evidence that we exist in a multiverse rather than a single universe. But, that discussion is a bit beyond the scope of this thread.
That last part is very true. Quantum computers could, in theory, allow us to do chemical and material simulations that would be impossible on classical computers. We could simulate all of the chemistry going on in the human body (including genetic and epigenetic interactions) and we could develop drugs accordingly. Things like clinical trials would become obsolete and we could wipe away many diseases as quickly as we could produce the drugs.
We could optimize an entire aircraft all in one go for a certain performance envelope (instead of iterating through shapes, materials, etc.)
We could develop superior materials along the lines of longer lasting concrete/cement, stronger steel, more durable rubber, and a thousand other things.
We could simulate climate systems much better.
We could design stronger magnets and we could better design fusion reactors known as “stellarators” and possibly attain stable fusion, commercially viable fusion.
Truly world changing stuff. The one caveat here is that quantum computing very much is a “problem of 9s”. While computational power increases with the number of q-bits, so does error rate. The “power” term researchers seem to have settled on is “quantum volume” which is a combination of q-bits and error rate. In order to increase power you must both increase q-bits and reduce error rate. Both appear to be formidable problems.
Andrew Lo discussed the issue of testing all currently approved drug compounds in combination as there is a school of thought that much of what we need in medicine exist, we just don’t know how to combine it
A friend is working on a collaboration to make the hiv cocktail a single pill
Quantum would obviously help, and when combined with genomics assist in developing personalised vaccines but…
No one has explained how 1 bit can be two things at once, two bits can be 8…
Andrew Lo discussed the issue of testing all currently approved drug compounds in combination as there is a school of thought that much of what we need in medicine exist, we just don’t know how to combine it
A friend is working on a collaboration to make the hiv cocktail a single pill
Quantum would obviously help, and when combined with genomics assist in developing personalised vaccines but…
**No one has explained how 1 bit can be two things at once, two bits can be 8 **…
I’m sorry to say that there is no easy answer to that question.
The explanation has a lot of layers. Fundamentally, the macro-size world we experience is very different from what goes on at a quantum scale. The roots of superposition and entanglement (which is what you’re really asking about) trace back more than a century to a phenomenon known as wave-particle duality. We think of waves and particles as fundamentally different things because that is our experience at our macro scale. The quantum world is much more complex.
Quantum Mechanics (specifically, the Schrödinger equation) does a very good job of describing quantum phenomena (mostly by reducing events to probabilities of events occurring), but a really poor job of explaining quantum phenomena. Even basic questions like “what is an atom?”, or if you want to go deeper, “what is a quark?” don’t have satisfying answers.
Consider the following as an example:
Suppose you are interested in the butterfly population in Sumatra. You have lots of data showing the number of butterflies vs time. You could come up with an equation that describes the data pretty easily. You could even just put it in an ExCell spreadsheet and fit a curve through the data points to generate such an equation. That equation is pretty useful and accurately describes the number of butterflies. It could even be used to make good predictions about what the population will look like a month from now, or next summer.
But, your equation does nothing to explain how or why the butterfly population changes as it does. It doesn’t address any of the more fundamental causes like climate, winds, predators, disease, etc.
Quantum Mechanics is much the same way. It describes quantum-scale phenomena really well, and is consistent with virtually all experiments devised to date. But, it doesn’t really explain how or why those phenomena occur.
The study of that how and why is called Quantum Foundations. There are currently a dozen or so seriously-regarded interpretations of quantum mechanics, and dozens more ideas that are, ummm, less rigorous.
Personally, I think Quantum Foundations is a fascinating field of study. It has the potential to answer, or at least hint at answering, some really big questions:
Do we have free will, or do we follow a pre-ordained destiny? (Note that this is a different question than whether we perceive that we have free will.)
Do we exist in a single universe or a multiverse?
What is consciousness?
What is time?
Is it possible to communicate faster than light?
Is it possible to travel faster than light?
Is there an afterlife?
Is there a God?
Cheers,
-Mike