First fully end-to-end quantum computer is a reality UPDATED

[bobsmith1492]

Originally posted by: EricMartello
You seem to forget that it wasn't until Hawking presented his ideas on singularities by merging the math behind classical and quantum physics that people stopped quarreling and started thinking. Before that, it was pretty divided. The whole idea behind the "quantum sciences" is to understand the universe and its workings at a fundamental level...but there's a lot we don't know yet. For example, what is dark matter? People who think they know something love to draw conclusions on inconclusive data...and while we have made some progress in our understanding of universal fundamentals, much remains a mystery. For example, we knew enough about atoms to make a nuclear weapon, and for the longest time people believed atoms were the fundamental particle in the universe.........until we discovered subatomic particles. And now, it's the same thing...sure, we can make devices that work based on theoretical principles, but that doesn't really prove anything other than we can make some nice CPUs and microscopes.

What did he merge between classical/quantum physics? Is there anything online to read?

 

[EricMartello]

Read about "hawking radiation" and his research and findings on that topic. That was his claim to fame, where he use quantum physics math to analyze a classical physics problem: what happens to stuff that gets sucked into a black hole. He concluded that it is ejected in the form of heat, which is also still a theory as far as I know.

 

[Born2bwire]

Originally posted by: EricMartello
You seem to forget that it wasn't until Hawking presented his ideas on singularities by merging the math behind classical and quantum physics that people stopped quarreling and started thinking. Before that, it was pretty divided. The whole idea behind the "quantum sciences" is to understand the universe and its workings at a fundamental level...but there's a lot we don't know yet. For example, what is dark matter? People who think they know something love to draw conclusions on inconclusive data...and while we have made some progress in our understanding of universal fundamentals, much remains a mystery. For example, we knew enough about atoms to make a nuclear weapon, and for the longest time people believed atoms were the fundamental particle in the universe.........until we discovered subatomic particles. And now, it's the same thing...sure, we can make devices that work based on theoretical principles, but that doesn't really prove anything other than we can make some nice CPUs and microscopes.

Well if a company claims to be building a device that works using a black hole, then I'd be sceptical. The ideas behind quantum computing though are empirically verified, like the phenomona of entanglement and superposition. What I would be sceptical about is if someone has built a complete quantum computer because as of now, implementation seems to be a good ways away from being finished or even agreed upon.

I'm not quite sure what the company DWave actually has though. Last year, scientists did create a 12 qubit computer, but DWave is talking about a 16 qubit processor that can actually run commercial applications.

 

[silverpig]

Originally posted by: bobsmith1492

Originally posted by: MrDudeMan

Originally posted by: EricMartello
I don't need to understand quantum mechanics...if it becomes something I can make money with, I will pay someone who knows what I need to know, but there's no denying that it is just theoretical. Yes, it's true that the some of the theories in QM can be applied to our physical reality, nobody can really tell us what exactly happens if we venture into a black hole, or what a black hole actually is. Hey, stephen hawking thought he had it figured out - for 30 years - then basically admitted he was wrong...so just because quantum theory is enduring doesn't mean it's how things actually are. Keep in mind we are trying to understand something in a way that is rational to us as humans. It's somewhat arrogant to think that we would even be able to comprehend the "truth" about this universe, because if it was something we could understand (and possible control) then essentially we'd elevate to "god like" status, right?

QM is more realistic than classical physics. as a matter of fact, classical physics can be derived from quantum physics. im not sure where you are trying to go with your arguement, but it doesnt make much sense. the fact is we can observe what happens around us and form theories to predict when/if it will happen again. that is what physics is all about. understanding how the world works, and QM does a good job of explaining it exactly.

Whoa, whoa, WHOA! Classical physics can be derived from quantum mechanics?

Last I'd heard, there was a huge gap between the world of the "big" and the world of the "small," and the world was waiting for someone to come up with the GUT - grand unifying theory - that would merge the two into a functional theory. String theory has been one attempt.

Would you mind deriving classical physics from quantum mechanics for me?

It works. You can apply QM to a baseball and compute its trajectory quite easily. And you get the exact same result you would classically. QM reduces to classical mechanics in the limit of quantum mechanically very large (or classically normal) energies.

 

[silverpig]

Originally posted by: EricMartello
You seem to forget that it wasn't until Hawking presented his ideas on singularities by merging the math behind classical and quantum physics that people stopped quarreling and started thinking. Before that, it was pretty divided. The whole idea behind the "quantum sciences" is to understand the universe and its workings at a fundamental level...but there's a lot we don't know yet. For example, what is dark matter? People who think they know something love to draw conclusions on inconclusive data...and while we have made some progress in our understanding of universal fundamentals, much remains a mystery. For example, we knew enough about atoms to make a nuclear weapon, and for the longest time people believed atoms were the fundamental particle in the universe.........until we discovered subatomic particles. And now, it's the same thing...sure, we can make devices that work based on theoretical principles, but that doesn't really prove anything other than we can make some nice CPUs and microscopes.

QM and classical physics were divided back in the Einstein/Bohr days. Bell's Theorem and some work soon after showed that the universe truly is quantum mechanical.

People don't know what dark matter is. That's true. But what we DO know is that there is something out there that has the exact properties fitting some kind of supermassive, weakly interacting particle. It is so blatantly obvious in cosmology that it'd be much more difficult to explain away than to find out what it is.

We knew there were subatomic particles long before we knew how to make an atomic bomb... it's pretty much required to do so.

 

[MrDudeMan]

Originally posted by: silverpig

It works. You can apply QM to a baseball and compute its trajectory quite easily. And you get the exact same result you would classically. QM reduces to classical mechanics in the limit of quantum mechanically very large (or classically normal) energies.

exactly what i meant...

in other words, the limit of quantum mechanics as "size" (macroscopic world) approaches infinity is classical mechanics

 

[EricMartello]

Originally posted by: Born2bwire
Well if a company claims to be building a device that works using a black hole, then I'd be sceptical. The ideas behind quantum computing though are empirically verified, like the phenomona of entanglement and superposition. What I would be sceptical about is if someone has built a complete quantum computer because as of now, implementation seems to be a good ways away from being finished or even agreed upon.

I'm not quite sure what the company DWave actually has though. Last year, scientists did create a 12 qubit computer, but DWave is talking about a 16 qubit processor that can actually run commercial applications.

It's funny that you mention "building a black hole". Have you heard some of the concerns being expressed about the new Hadron super collider experiments that are scheduled to take place? Some people believe that it could generate singularities as a result...I doubt the mass of the particles, even if multiplied exponentially, would come close to matching that of a collapsed star, but it is interesting...and somewhat disturbing...to think that a black hole could be artificially created and possibly cause a lot of trouble here on earth.

With quantum computing - isn't it true that positions of qubits are predicted and not absolute, as they are in a digital system? That means that calculations performed on a QC may become increasingly arbitrary as the complexity increases. Seems like QC is similar to how the human brain works, more than a CPU.

 

[MrDudeMan]

Originally posted by: EricMartello

Originally posted by: Born2bwire
Well if a company claims to be building a device that works using a black hole, then I'd be sceptical. The ideas behind quantum computing though are empirically verified, like the phenomona of entanglement and superposition. What I would be sceptical about is if someone has built a complete quantum computer because as of now, implementation seems to be a good ways away from being finished or even agreed upon.

I'm not quite sure what the company DWave actually has though. Last year, scientists did create a 12 qubit computer, but DWave is talking about a 16 qubit processor that can actually run commercial applications.

It's funny that you mention "building a black hole". Have you heard some of the concerns being expressed about the new Hadron super collider experiments that are scheduled to take place? Some people believe that it could generate singularities as a result...I doubt the mass of the particles, even if multiplied exponentially, would come close to matching that of a collapsed star, but it is interesting...and somewhat disturbing...to think that a black hole could be artificially created and possibly cause a lot of trouble here on earth.

With quantum computing - isn't it true that positions of qubits are predicted and not absolute, as they are in a digital system? That means that calculations performed on a QC may become increasingly arbitrary as the complexity increases. Seems like QC is similar to how the human brain works, more than a CPU.

IIRC particle accelerators already create "artificial" black holes. they are so small, however, that they evaporate almost immediately.

 

[f95toli]

Originally posted by: EricMartello

With quantum computing - isn't it true that positions of qubits are predicted and not absolute, as they are in a digital system? That means that calculations performed on a QC may become increasingly arbitrary as the complexity increases. Seems like QC is similar to how the human brain works, more than a CPU.

No. Of course it depends on what kind of qubit you are using; if it is a molecule in a gas then it won't stay put but that in itself has nothing to do with it being a qubit.

Qubits are simply controllable 2-level systems (i.e. the system has two states of energy) that is so well decoupled from the environment that their decoherence time (the time they behave "quantum mechanically") is reasonbly long.
E.g. the qubits used by D-wave Systems are probably something like 10x10 micrometer in size, fabricated in superconducting metal (aluminum or niobium) on a silicon waffer; i.e they definitly won't move. It is just an ordinary microchip.

Btw, "reasonably long" in the case of a superconducting qubits is something like 1 microsecond. We are trying to make qubits with a longer decoherence time (at the moment the time seems to limited by a certain step in the fabrication process, to be more precise the formation of an oxide layer) but since these qubits are usually controlled using microwave pulse which a have a risetime <1ns there is still enough time to manipulate them.
The challenge now is to find ways to couple more qubits together, there are some fundamental problems with that (it get exponentially harder to add more qubits) but the system used by D-Wave circumvents that problem to an extent since only next-nearest neighbor interaction is used (i.e. the qubits are not all direcly coupled).

 

[blackllotus]

Originally posted by: EricMartello
It's funny that you mention "building a black hole". Have you heard some of the concerns being expressed about the new Hadron super collider experiments that are scheduled to take place? Some people believe that it could generate singularities as a result...I doubt the mass of the particles, even if multiplied exponentially, would come close to matching that of a collapsed star, but it is interesting...and somewhat disturbing...to think that a black hole could be artificially created and possibly cause a lot of trouble here on earth.

Its not troubling at all if you think about. A black hole created by the collision of two particles will have the same mass of those two particles. Its gravitional pull on other objects will be so small and its event horizon so miniscule that its highly unlikely it will even suck in one photon before it evaporates.

 

[EricMartello]

Originally posted by: blackllotus

Originally posted by: EricMartello
It's funny that you mention "building a black hole". Have you heard some of the concerns being expressed about the new Hadron super collider experiments that are scheduled to take place? Some people believe that it could generate singularities as a result...I doubt the mass of the particles, even if multiplied exponentially, would come close to matching that of a collapsed star, but it is interesting...and somewhat disturbing...to think that a black hole could be artificially created and possibly cause a lot of trouble here on earth.

Its not troubling at all if you think about. A black hole created by the collision of two particles will have the same mass of those two particles. Its gravitional pull on other objects will be so small and its event horizon so miniscule that its highly unlikely it will even suck in one photon before it evaporates.

Yeah, I said that didn't I? I was referring to the ability to create a black hole, one that does have enough mass to be a threat, which is a possibility. Who's to say that in the future, our curiousity about black holes leads us to create one like that for research. You don't find that disturbing? Maybe it's not, getting sucked into a black hole may be lethal, but at least we'd know what happens on the inside.

 

[MrDudeMan]

Originally posted by: bobsmith1492

Originally posted by: MrDudeMan

Originally posted by: EricMartello
I don't need to understand quantum mechanics...if it becomes something I can make money with, I will pay someone who knows what I need to know, but there's no denying that it is just theoretical. Yes, it's true that the some of the theories in QM can be applied to our physical reality, nobody can really tell us what exactly happens if we venture into a black hole, or what a black hole actually is. Hey, stephen hawking thought he had it figured out - for 30 years - then basically admitted he was wrong...so just because quantum theory is enduring doesn't mean it's how things actually are. Keep in mind we are trying to understand something in a way that is rational to us as humans. It's somewhat arrogant to think that we would even be able to comprehend the "truth" about this universe, because if it was something we could understand (and possible control) then essentially we'd elevate to "god like" status, right?

QM is more realistic than classical physics. as a matter of fact, classical physics can be derived from quantum physics. im not sure where you are trying to go with your arguement, but it doesnt make much sense. the fact is we can observe what happens around us and form theories to predict when/if it will happen again. that is what physics is all about. understanding how the world works, and QM does a good job of explaining it exactly.

Whoa, whoa, WHOA! Classical physics can be derived from quantum mechanics?

Last I'd heard, there was a huge gap between the world of the "big" and the world of the "small," and the world was waiting for someone to come up with the GUT - grand unifying theory - that would merge the two into a functional theory. String theory has been one attempt.

Would you mind deriving classical physics from quantum mechanics for me?

I realize this comment is a little bit late, but I thought it would be a good idea to correct the above post in case someone wanders in here and reads this thread. The GUT is not meant to bridge the gap between quantum and classical physics as there really isn't one. The GUT is supposed to unify the gravitational, nuclear strong and weak, and electromagnetic forces. The electromagnetic and weak nuclear force have already been reconciled; it is called the electroweak force.

 

[cougar1]

Isn't next-nearest neighbor interaction enough? It's been a few years since I've studied quantum computers, but as I recall, there are techniques (at least for some systems) by which the next-nearest neighbor interaction can be used to couple in additional qubits. In other words, couple A to B then couple B, which is already coupled to A, to C. In this case C becomes coupled to A even though there was no direct interaction between A and C.

Of course such a sequence requires more operations, which requires more time, getting back to your point about the need to increase decoherence times. Nevertheless, it does allow a way around the problem of long-range coupling.

Correct me if I'm wrong.

 

[bobsmith1492]

Originally posted by: MrDudeMan

Originally posted by: bobsmith1492

Originally posted by: MrDudeMan

Originally posted by: EricMartello
I don't need to understand quantum mechanics...if it becomes something I can make money with, I will pay someone who knows what I need to know, but there's no denying that it is just theoretical. Yes, it's true that the some of the theories in QM can be applied to our physical reality, nobody can really tell us what exactly happens if we venture into a black hole, or what a black hole actually is. Hey, stephen hawking thought he had it figured out - for 30 years - then basically admitted he was wrong...so just because quantum theory is enduring doesn't mean it's how things actually are. Keep in mind we are trying to understand something in a way that is rational to us as humans. It's somewhat arrogant to think that we would even be able to comprehend the "truth" about this universe, because if it was something we could understand (and possible control) then essentially we'd elevate to "god like" status, right?

QM is more realistic than classical physics. as a matter of fact, classical physics can be derived from quantum physics. im not sure where you are trying to go with your arguement, but it doesnt make much sense. the fact is we can observe what happens around us and form theories to predict when/if it will happen again. that is what physics is all about. understanding how the world works, and QM does a good job of explaining it exactly.

Whoa, whoa, WHOA! Classical physics can be derived from quantum mechanics?

Last I'd heard, there was a huge gap between the world of the "big" and the world of the "small," and the world was waiting for someone to come up with the GUT - grand unifying theory - that would merge the two into a functional theory. String theory has been one attempt.

Would you mind deriving classical physics from quantum mechanics for me?

I realize this comment is a little bit late, but I thought it would be a good idea to correct the above post in case someone wanders in here and reads this thread. The GUT is not meant to bridge the gap between quantum and classical physics as there really isn't one. The GUT is supposed to unify the gravitational, nuclear strong and weak, and electromagnetic forces. The electromagnetic and weak nuclear force have already been reconciled; it is called the electroweak force.

Thank you, I guess I had those confused.

 

[MrDudeMan]

Originally posted by: bobsmith1492

Thank you, I guess I had those confused.

No problem. If it makes you feel any better, I actually said the same thing you did to a professor during an oral test. I'm not sure why there is an affinity to get those two concepts confused but you aren't the only one.

 

[bobsmith1492]

Originally posted by: MrDudeMan

Originally posted by: bobsmith1492

Thank you, I guess I had those confused.

No problem. If it makes you feel any better, I actually said the same thing you did to a professor during an oral test. I'm not sure why there is an affinity to get those two concepts confused but you aren't the only one.

So, to get this straight, quantum mechanics can be used on a large scale to predict movement of objects similar to classical physics/mechanics.

The intra-atomic forces are not completely understood - that would be the idea of passing particles back and forth being the cause of the strong force (or weak, the one that holds protons/neutrons together in a nucleus?); however, the idea of a "graviton," or gravity particle, is still up in the air, no? String theory predicts it to be similar to a photon, i.e. no mass. Am I correct on these then?

 

[silverpig]

Originally posted by: MrDudeMan
IIRC particle accelerators already create "artificial" black holes. they are so small, however, that they evaporate almost immediately.

Nope, they can't. And we have absolutely no hope of ever doing it unless there are extra dimensions. Right now, in order to cause two electrons to collide together with enough energy to form the smallest possible black hole would require 10^19 GeV of energy. LHC will have an energy of ~30 TeV IIRC, or about 3x10^4 GeV. So LHC would have to be about a quintillion times more powerful in order to make it work.

However, if you add a few extra dimensions, the energy required goes down dramatically. If there are something like 6-8 extra dimensions a millimeter large, then LHC could produce a mini singularity, but it would evaporate in about the time it would take for light to cross it (ie, super quick).

String theorists would LOVE to see a black hole formed in LHC. While it would not be a proof of string theory at all, it would prove that there are extra dimensions which are small. The main thing that people who don't like string theory don't like about string theory is the seemingly arbitrary inclusion of some number of extra dimensions which we have no reason to have right now.

 

[MrDudeMan]

Originally posted by: silverpig

Originally posted by: MrDudeMan
IIRC particle accelerators already create "artificial" black holes. they are so small, however, that they evaporate almost immediately.

Nope, they can't. And we have absolutely no hope of ever doing it unless there are extra dimensions. Right now, in order to cause two electrons to collide together with enough energy to form the smallest possible black hole would require 10^19 GeV of energy. LHC will have an energy of ~30 TeV IIRC, or about 3x10^4 GeV. So LHC would have to be about a quintillion times more powerful in order to make it work.

However, if you add a few extra dimensions, the energy required goes down dramatically. If there are something like 6-8 extra dimensions a millimeter large, then LHC could produce a mini singularity, but it would evaporate in about the time it would take for light to cross it (ie, super quick).

String theorists would LOVE to see a black hole formed in LHC. While it would not be a proof of string theory at all, it would prove that there are extra dimensions which are small. The main thing that people who don't like string theory don't like about string theory is the seemingly arbitrary inclusion of some number of extra dimensions which we have no reason to have right now.

I'm glad i prefaced with "IIRC" because I guess I was wrong. I'm not sure why I thought that or where I read it, but nevermind.

 

[f95toli]

Originally posted by: bobsmith1492

So, to get this straight, quantum mechanics can be used on a large scale to predict movement of objects similar to classical physics/mechanics.

The intra-atomic forces are not completely understood - that would be the idea of passing particles back and forth being the cause of the strong force (or weak, the one that holds protons/neutrons together in a nucleus?); however, the idea of a "graviton," or gravity particle, is still up in the air, no? String theory predicts it to be similar to a photon, i.e. no mass. Am I correct on these then?

Yes, you can use QM on a "large scale". There is no explicit dependence on scale when it comes to QM, it is just that large objects tend to have manya cat i extree degrees of freedom whcih "washes out" the quantum effects. Moreover, the calculations quickly become extremely complex as you add more degrees of freedom. BUT (and this is important) we DO understand why we never see any half-dead cats; the cat is simply too large (too many degrees of freedom).

Note that there is a dependence on mass (the de Broglie wavelength for extremely short) but that it itself does not prevent QM effects to be seen in the macroscopic world; superconductors and superfluid helium-4 are good examples of that. As I pointed out above; they qubits D-wave are using are LARGE (something like 10x10 um), they are most definitly macroscopic.

The intra-atomic forces ARE undestood, at least at the energy scales that we come across in the universe today. The particles responsible for the strong and weak interaction have been observed in particle accelerators.
What we don't understand is how to to "combine" QM and general relativity, we don't have a quantum theory for gravity.

 

[silverpig]

Originally posted by: MrDudeMan

I'm glad i prefaced with "IIRC" because I guess I was wrong. I'm not sure why I thought that or where I read it, but nevermind.

It's still an interesting idea, and probably the best test right now for the existence of many small extra dimensions. It's been written about in pop culture quite a bit too.

 

[Blouge]

Eric, I don't think any laboratory experiment has ever revealed an error in QM's predictions. It might not be the truth behind the universe (I agree it's not), but it's certainly accurate enough to build some technology based on it.

My dim understanding is that quantum computers work based on particles in a superposition of states collapsing into some quantum state that satisfies the constraints of the problem. What happens if you ask it an impossible problem? Like find boolean variables x and y satisfying the expression E, "x AND y AND NOT (x OR y)"? Is the idea to just ask "E OR z", and then keep trying until z becomes false? In this case z could never be false, so I'd guess you'd have to wait N trials and then know that there is no answer, with probability 1 - 2^N. Is this explanation anywhere near the mark? If you have N binary variables, with only a single combination that satisfies the statement, wouldn't you have to try about 2^N times to have a chance of getting this answer, as opposed to just garbage? How is this better than an exhaustive search on a traditional computer?

 

[imported_iNGEN]

Quantum computing..oh man...I have to appreciate the subtle irony found in "developing" hardware based on a branch science that is essentially just a theory. My understanding of quantum mechanics is minimal, but it comes across as "mathematical faith". We couldn't figure out how the universe works on the lowest levels so we created quantum mechanics as our little messiah, which lets us makes theories work - even if these theories do not necessarily carry over into our reality.

Following with your perspective, and I agree it is a valid one, nearly all that is known is theory.

The entire field of chemistry is theory, nothing more than theory. Many of the principles are described as laws simply because they are theories so close to correct it would be inappropriate to describe them in uncertain terms. Ideas like valence, atomic weight, atomic number, etc. These properties, when incorporated into the current theoretical model, work so well (so accurately predict behavior) that they can't be wrong. They may need to be adapted in the future. That is to say, they may be incomplete, but they are not wrong.

Much of quantum theory is now approaching the kind of precision we find in chemical laws. Quantum theory isn't quite there, yet, but enough of the now standard theory accurately predicts behavior that it is better to describe the field of quantum theory as incomplete, rather than "mathematical faith".

Theory is just modeling. And to quote William S Gosset, "The whole of the value of any model is its ability to predict future observed behavior."

 

[verndewd]

Yup ;if you can afford the liquid nitrogen to cool it and program the cpu to run windows ,you are in like flynn.

 

[silverpig]

Originally posted by: verndewd
Yup ;if you can afford the liquid nitrogen to cool it and program the cpu to run windows ,you are in like flynn.

LN2 is cheaper than bottled water...

 

[f95toli]

Originally posted by: silverpig

Originally posted by: verndewd
Yup ;if you can afford the liquid nitrogen to cool it and program the cpu to run windows ,you are in like flynn.

LN2 is cheaper than bottled water...

Yes, but LHe4 is not. I think it is somewhat cheaper in the US than here in Europe but a dilution fridge still uses about 200-300 liters of it per week (it depends on the model, wiring etc) meaning the total running costs of a fridge is still probably something in the range $1000-2000 per week.

LN2 is unfortunately nowhere near cold enough to cool down a solid state quantum computer.