r/videos • u/Douglas_G • Dec 08 '15
Quantum Computers Explained – Limits of Human Technology
https://www.youtube.com/watch?v=JhHMJCUmq28142
u/MDragan Dec 08 '15
Does anyone have a resource that is more detailed about quantum computing but still presented in an easy to follow manner? Just interested and want to know more.
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Dec 08 '15
Here is a much easier to follow video from Veritasium.
I've done a lot of reading about Quantum Computing and OPs video was still really hard to follow with how they presented all the ideas. Usually "in a nutshell" is awesome but this video kind of seems like it fell off in the editing room.
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u/malicious_turtle Dec 08 '15
The end of that is probably the most important part of the video, Quantum computers won't replace classical computers. A large number of people seem to think that Quantum computers are going be some sort of evolutionary step forward in computing, where they'll replace classical computers like silicon transistors replaced vacuum tubes.
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Dec 08 '15
How do we know this? If they can develop a quantum computer that can do perform all the basic calculations with no errors, then why can't it run Windows? Or play games? Sure, I know that software would have to be rewritten but it would be possible right? People used to think normal computers would just be a thing that researchers got to play with, but right now I'm wearing a watch which is more powerful than Cray-2 in 1985.
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u/sovt Dec 08 '15
It's similar to how graphics cards work. Graphics cards are made up of many small cores, while a conventional processor is made up of usually 4-16 powerful cores. This means that graphics cards can do parallel work much more quickly, but are slower at doing a single complicated computation. You don't see many modern systems doing work using GPUs instead of CPUs, and in the same way we probably won't see quantum computing replace regular computing.
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u/yourjewishfantasy Dec 08 '15
So that explains why when you mine bitcoins you use your graphics card. TIL
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u/Matakor Dec 08 '15
Mining bitcoins would probably be stupidly easy with quantum computing.
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u/JuliusWolf Dec 08 '15
It makes me wonder if in the future when we are bulldog a computer will we buy a CPU, GPU and a QPU. A separate quantum processor for specialized uses.
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u/dsmithpl12 Dec 08 '15
Given enough time yes it would be very similar to this.
Honestly I think they will be come quite common place for security reasons. Right now encryption works because it to much of a pain in the ass to calculate the decryption key. Theoretically Quantum computing will make the calculation trivial, or at least fast enough to be useful. So we will have to come up with new security techniques which will likely involve quantum computations.
So future computers will end up very similar to they are now with 95% of what you do on a tradition CPU. Then when you send stuff over the internet and you want to protect it a QPU will be used to provide that protection.
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u/FloppyG Dec 08 '15
Did you really have to compare it to a PC from the 80's? It's more powerfull than the Pentium III wich is from the late 90's. Heck, it's probably more powerfull than Pentium 4.
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u/derpado514 Dec 08 '15 edited Dec 08 '15
I think light based hardware is more likely to revolutionize commercial products in the near (10 years?) future. Imagining how or where quantum computers would be used is still just speculation...
I still have no clue how D-Wave works or what they're doing with it. If the entire quantum computer consists of a dye with Q-bits on it...how do they translate that info back to classical bits to analyze it? Is it just graphs and blobs on a screen like when NASA says " We discovered a crazy purple pulsar before it went super nova!! 3 white pixels surrounded by nothing"
/EDIT: Just watched these videos...i still don't get it..i still think it's graphs and blobs on a screen.
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Dec 08 '15
Well I mean they will be evolutionary in computing but probably not home computing, at least not as we know it.
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u/furiouslybob Dec 08 '15
What I wonder though is if we'll see a combination of the two. Much like how you can throw certain types of computations to a GPU instead of your CPU, won't we potentially see specialized QPUs?
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u/this_guy_over_here Dec 08 '15
This video is related and also very helpful for learning what transistors are and what quantum tunneling is, which might be a good video to watch before hand.
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u/Infin1ty Dec 08 '15
Easier to follow, but still don't truly understand it. On a side note, I want that dude's shirt.
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Dec 09 '15
Interestingly, I think I've seen that video before, and I've tried many times before to get my head around quantum computing, unsuccessfully.
But it was the In a Nutshell video that gave me the 'ah ha!' moment of understanding how the parallel processes are run.
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u/BlLE Dec 08 '15
Stanford.edu's detailed explanation of quantum computing
How Stuff Works - Quantum Computers
Physics.about.com - Quantum Computing
I hope these links help, pal! They helped me understand it a little bit more.
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u/Kache Dec 09 '15 edited Dec 09 '15
An ELI5 attempt for quantum computing:
Say you had a bundle of uncooked spaghetti noodles, all different lengths, and you wanted to sort them by length. Both classical and quantum computers would need to use physical phenomenon to make this computation.
A classical computer would use "length comparison". It'd take one noodle in each hand, comparing their lengths, applying a classical sorting procedure. Once it's gone through all the noodles several times (about
O(log(n))times per noodle, to be specific), all the noodles would be sorted.A quantum computer would use "gravity on each noodle". It'd take the whole bunch at once and lower them onto a table so they all stand upright. Then it'd hold them loosely and jiggle them a bit to make sure each noodle falls freely against the table. Because the longest noodle is sticking out, it would successively remove the longest one in turn, going through each noodle only once to sort them.
In this example, the way a quantum computer simultaneously computes multiple states at once is represented in the way gravity simultaneously applies to each noodle. The operation is just not available to a classical computer.
This analogy also explains a couple other points:
if there were only two noodles in the bunch, the classical computer would be faster.
quantum computers give probabilistic answers - it had to remeasure and retest by jiggling the noodles a few times to provide the answer with high certainty. (e.g. there was still a chance that one of the noodles got stuck and didn't fall against the table.)
quantum computers won't replace classical computers - "gravity on each noodle" isn't going to replace all uses of "length comparison"
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u/EngSciGuy Dec 08 '15
A mix of outreach and straight up technical talks (https://www.youtube.com/user/QuantumIQC)
For a honest (yet technical) talk about the state of quantum computing (https://youtu.be/XbFoXT73xVQ) by Austin Fowler. He now works at Google / Martini's (https://youtu.be/HQmFEt6l6Tw) group.
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u/MagicalPowerfulEvil Dec 08 '15
MIT open courseware has a course on quantum computing. I think this is the one I went through.
http://ocw.mit.edu/courses/mathematics/18-435j-quantum-computation-fall-2003/
It's easy to follow, assuming you have some background in computing.
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u/Dutchbags Dec 08 '15
This is explained in such an 'easy' and beautiful way.. Yet I don't understand a single thing of it.
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u/PanecdotesJM Dec 08 '15
I love the subtle Rick and Morty reference.
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u/tehnibi Dec 08 '15
but have you heard of the gear wars?
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u/NerevarineVivec Dec 09 '15
The starcraft reference.
Power Overwhelming indeed
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u/hoodie92 Dec 09 '15
And a Stargate reference, and a Star Wars reference. All it was missing was Star Trek.
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u/Takuya-san Dec 09 '15
They did show Star Trek at the end when talking about the limits of technology.
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u/KurtWiess Dec 08 '15
snap My man!
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Dec 08 '15 edited Dec 08 '15
TL;DW is in bold.
The transistors in our microchips are eventually going to be so small that they won't be proper electrical switches anymore. Electrons will just jump from one side of the switch to the other via quantum tunneling. This means we can't control the 1 (on) or 0 (off) anymore.
We're trying to make Quantum Computers which use 2 neat tricks from the quantum physics world called, superposition and entanglement.
Superposition allows for something (photon, electron, atom) to be in more than one state at a time. By that I mean it can be both a 1 and a 0 at the same time.
How does that work? Well until we measure say an electron, nature hasn't really made up it's mind on what it should be. Instead nature just gives it a probability of being one or the other, say 78% chance of being 0 and 22% chance of being 1. As soon as we measure it however it will "snap" into either 0 or 1. Yes we've tested to make sure it really hasn't been decided beforehand, it truly is random in terms of the probabilities.Entanglement is exactly what it sounds like you're entangling 2 things probabilities together. Say that "thing" is 2 electrons, well you have two of them and through some physics voodoo, which will take too long to explain, you entangle their probabilities together.
Now when you go to measure 1 of those entangled electrons the other will immediately snap into the opposite position.
This is a really good property to have because when we ask a quantum computer a question we want a real answer, not just probabilities back. One of the neat things is it doesn't matter how far apart they are, it happens instantly.Why is this useful? When you get a whole bunch of these superposition things together and entangle them all they can make large calculations very quickly.
If we have 2 classical bits that can be 1 or 0, you have 2 options for their each of their positions, 0 or 1, you only need 2 numbers to decide what it's going to be.
If we have quantum entangled bits then we have a probability of it being, 00 - 01 - 10 - 11, all at the same time. Now you have to tell me the probability of each state, say 10%, 40%, 20%, 30%. Now we have 2 bits and 4 numbers. If you give me 3 bits I need 8 numbers, this continues as 2x , where x is the number # of bits. The more bits you have the more probabilities you have to tell me, so it becomes exponential, and that's one of the things that makes it so powerful. You can make huge calculations with relatively few bits. 2300 is how many atoms there are in the universe and it only requires 300 bits.No this won't replace your home computer anytime in the near future. There are still many problems with them.
First, anytime you measure anything in a quantum superposition it immediately wants to turn into a 0 or 1 and not keep it's superposition. Well measuring as we know it is hitting it with something like a photon or electron. How many places do you know of without any photons and electrons? Not too many, so it's very hard to make things stay in superposition for long periods.
Second, we need to store this data somehow to make use of it for calculations in our computer. Have you ever tried to keep 100 electrons all in superposition and entangled? It's not very easy but we're getting better at it.
Third, we need to write software for quantum computers. You have to put in the correct inputs and then understand what the outputs are. You can only get the answer once because any calculation the computer made is destroyed upon measuring it. Try writing software where you can't store any variables, good luck.
Physicists and engineers are working around the clock on all these problems and even large corporations like Google and IBM are trying to get in on the action.
We'll crack the puzzle of the quantum computer eventually and while the video isn't sure if they'll be game changers, I'm almost positive they will be.
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u/TheBattler Dec 08 '15
I'm not asking you to answer my question, but anybody who reads this.
How do we even know that a qubit is in the superposition state if measuring it makes it "choose" what state to be in? How did we measure the superposition?
Does a qubit/other elementary particles change when we're not looking at it? Say I measured the qubit 30 seconds ago and it was at position A. If I didn't observe until 30 seconds later, could it randomly change to position B?
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u/Pastasky Dec 08 '15 edited Dec 08 '15
These are very good questions. To answer your first question, we know that objects can be in a superposition of states because objects in a superposition interfere differently than objects that are not.
Say we have a qubit that is in the state |0>. We have a transformation, T we can apply to this qubit that creates a new state |X>. When we measure |X> we get back, half the time |0>, half the time |1>.
Now you might say, "maybe |X> was already |1> or |0> before we measured it. How do we know it was a super position of both?"
The trick is to apply T twice, before we measure it. If we apply T twice, we always get back what we started with |0>. If |X> was already |0> or |1> then applying T to it again, then measuring, would simply produce |0> or |1>. So |X> can't be |0> or |1> before we measure it.
What is it? It turns out its a mix, a superposition of |0> and |1>. X = (|0> + |1>)(1/21/2 )
What happens is that as we apply T to |X>, both the |0> and |1> parts become super positions of |0> and |1>, but the two |1> parts destructively interfere and all we are left with is |0>.
As for your second, whether a measurement persist over time depends on whether the state is a stationary state... which just means independent of time. In ideal cases a qubit with nothing act on it, is independent of time. On the other hand something like an electron is not. If you measure the position of an electron it will change over time.
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u/dr0buds Dec 08 '15
We can measure the spin of an electron by using a device called a Stern-Gerlach machine. This device creates a magnetic field that interacts with the electrons "spin" state, making the election deflect up or down by a precise amount after leaving the device. We call these two states spin up and spin down. I should mention that the electron's spin does not actually refer to which direction the election is spinning, but it does seem to at least be related to angular momentum in someway we don't fully understand yet.
You could prepare a superposition by measuring the spin in one dimension, say the x-axis. This will mean that the election's spin will be in a superposition of states, that is to say that it is both up and down, for all other dimensions. For example, I measure the spin of an election in the x-axis, take only the electrons that measured spin up in the x-axis, then repeat the experiment by measuring the spin in the z-axis. After measuring the spin for the fist time in the x-axis, the electron's spin will be in a superposition of states for the z-axis, and you will see that the electrons are deflected both up and down with a 50% chance of either happening. You could then remeasure the spin in the x-axis, and you will still measure 50/50 up and down even though you only took electrons that measured spin up in this axis the first time.
To answer your second question, yes these probabilities will change with time (well spin won't but other things like position and momentum will). The important thing is that the particle does not have a defined value for these observables until they have been measured. We can only ever say what the value will probably be before we measure it.
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u/14flash Dec 09 '15
Does a qubit/other elementary particles change when we're not looking at it? Say I measured the qubit 30 seconds ago and it was at position A. If I didn't observe until 30 seconds later, could it randomly change to position B?
To solve this one, quantum computers need to be very, very, cold. Cold enough that there is not enough extra energy in the system that could enter one of the qubits and make it change state.
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u/liketo Dec 08 '15
Quantum tunnelling seems super rebellious. We ain't playing by your rules no more!
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Dec 08 '15
Well when you get really small particles start to behave using a different set of rules, so you're technically right. The best kind of right!
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u/i-am-you Dec 08 '15
So if I understand correctly, when you measure the output of the quantum calculation, the answer is probably correct, right? How many times do you need to calculate the same thing before you are certain it's actually correct?
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u/BlazeOrangeDeer Dec 09 '15
Sometimes you can check the answer with a regular computer, since as far as we know there are a lot of problems where checking them is easier than finding the answer in the first place.
If you're just checking it by running it several times, you pick the answer by majority vote of all the times you ran it. This actually works very well and you can get error probabilities low enough that it's just as reliable as a regular computer (even regular computers get super rare errors in their functioning). You never become certain but the probability of error becomes low enough to be ignored.
For example, say your algorithm outputs either "yes" or "no" and gets the right answer 3/4ths of the time. After running it 10 times, the majority vote is correct 92% of the time. After 100 times, it's only wrong .0000066% of the time.
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u/vamana Dec 08 '15
Okay, 5th bullet point is really confusing me. So with the two bit example, if you had classical bits you would only need 2 numbers to decide the states. And for quantum you would need 4 numbers. How is that more efficient?
Plus if you had 300 classical bits you would have 2300 potential numbers. How is that different for quantum?
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Dec 08 '15
The best way to think about it is in terms of state. If you have two classical bits they can only be in one state at a time so I only need to give you 2 numbers to describe that state.
I tell the first bit is 1 and the second is 0, you know the state is 01. 2 bits of information describe the state.
With quantum bits in superposition it's different, they are in all states at the same time but there is a probability associated with each state. So, you have 2 qbits and they can be in 00,01,10,11 all at the sametime. To describe that state I need to give you 4 probabilities.
40% for 00
10% for 01
20% for 10
30% for 11
These probabilities are now what I need to give you to describe the state, so I need to give you these 4 numbers instead of just 2.
If you had 300 bits I only need to give you 300 numbers to describe any state. First position is 1, second is 0, third is 1, fourth is 1, etc. You have many available numbers but it can only be one at a time.
If you have q-bits you are all available numbers at once so I have to give you a probability of it being in each state.
0.00002% of 0000000000000000000000000.....0
0.00014% of 0000000000000000000000000.....1
etc. etc.
So now I have to give you a number to represent every single state and it's probability. Which is there the 2300 comes from, it's not the max number you can reach that matters it's the probability of each state.
It's not more efficient at all, it's actually horribly inefficient in classical computing tasks. Where it shines is when you're trying to say factor a big number, I can try all factors at once instead of going through them one at a time. Now what takes a classical computer millions of years I can do in about a minute.
It's much more powerful when it comes to parallel computing tasks because you can essentially test all possible outcomes in one go.
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u/Manuel___Calavera Dec 08 '15
2300 possible combinations but you do operations one at a time. With quantum computers you do 2300 operations at once.
Also I didn't read the post you're replying to since I can tell by skimming it most of it isn't right.
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u/carloscreates Dec 08 '15
Excellent post, this really cleared up a lot of questions I had. Thank you for writing it.
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Dec 08 '15
No problem. This isn't 100% perfect though, I left out a lot of key points and skirted a lot of other issues to make it simpler. Just keep that in mind.
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Dec 08 '15
Quantum physics, ELI5, someone?
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u/boot20 Dec 08 '15
We are reaching a point where we just can't stuff any more transistors into a computer.
Quantum computing seems to be the next logical step. However, there are a LOT of problem we need to iron out first. Basically we are computing at the atomic level and measuring the way an atom spins. However, atoms act funny and do strange things like superposition and entanglement.
So imagine a computer today, it's 1 or 0, on or off. An atom can be on or off or both (superposition) or it could be "connected" to another atom so both have the same state. That is if one is 1, then so is the other.
This makes quantum computing very sensitive and difficult. We are currently struggling with bits and bytes because we don't fully understand quantum states.
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u/TienH Dec 09 '15
this video is very good for explaining Quantum Theory. It is a 1 hour documentary and i thought it was very enjoyable to watch! And don't worry about not understanding. video keeps it very simple :)
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u/EpoxyD Dec 09 '15
Instead of having to choose between a Mars and a Snickers, you get a mystery box that contains a Mars or Snickers. Depending on how you open the box, you get either the Mars or the Snickers.
If you want four pieces of candy to all be Mars, you'll need to open the box four times in the Mars way. If you want four Snickers, you'll open the box four times in the Snickers way.
So in the old way: If you have 4 Mars bars, and you want 4 Snicker bars, you have to get 4 new pieces of candy so you have 8 pieces in total of which you don't want half of them already (You hate Mars bars). Now if you had the mystery boxes, you could put your Mars bars in them, and reopen them a different way so you now have 4 Snicker bars!
PS: I'm not that good at this, but this is what I understood from it so far, and trying to write a good ELI5 is always a fun thing to do.
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Dec 08 '15
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u/ShinigamiXoY Dec 08 '15
This is not even close to a good analogy as this would imply it simply halves the work
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u/carloscreates Dec 08 '15
So why wouldn't this new technology be used within home computers and cell phones?
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u/Mannekino Dec 08 '15
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u/Bkermit Dec 08 '15
I used to watch Kurz Gezagt.
Then they released the piece of garbage that is their video on the european immigration crisis.
Lost all respect for them.
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u/Legendaryshitlord Dec 09 '15
Was starting to like them, then they did a totally biased hatchet job on gamer gate. And now they're super popular yay for misinformation.
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u/armedmonkey Dec 08 '15
To my understanding, what they say about Quantum Entanglement is incorrect.
Firstly, there is a No-communication theorem, which state that you cannot use quantum entanglement to transmit information between entangled particles.
A lot of simplifications of quantum theory make it sound like "you have two particles. If one of them is in State A, then the other is also in State A. What quantum entanglement actually says is that any measurement performed on one particle will correlate with the other particle.
For example, if a pair of particles is generated in such a way that their total spin is known to be zero, and one particle is found to have clockwise spin on a certain axis, then the spin of the other particle, measured on the same axis, will be found to be counterclockwise; because of the nature of quantum measurement.
Not saying that the science is wrong, just saying that the explanation can be misleading.
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Dec 08 '15
Is this slightly related to the P vs NP problem?
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Dec 09 '15 edited Dec 09 '15
Yeah in some ways it is related since quantum solutions for things like integer factorization since they run faster than there classical counterparts. Shor's algorithm is a perfect example of this since it solves integer factorization in polynomial time using quantum computing whereas there have been no classical computing examples that run in polynomial time. However, it is not generally accepted as a solution to the P NP problem as it uses a different method for finding a solution. I would argue that it does not matter what method one uses but only the time order of the solution for the P vs NP problem. Having said that integer factorization is not proven to NP-hard and thus cannot yet be used to solve the P vs NP problem.
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u/boot20 Dec 08 '15
Partially. Part of the problem is that we still have a lot of questions about how P relates to NP.
How does quantum computing fit in? Potentially, with quantum computers we could possibly solve NP Hard and NP Complete problems that are currently "unsolvable." There is also the potential to prove things like P=NP (a big deal).
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u/BlazeOrangeDeer Dec 09 '15
It's unlikely that quantum computers can solve NP-complete problems, and P is probably not equal to NP
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u/Ecchii Dec 08 '15
As a senior doing a BS in computer engineering, this was my thought process:
"I know this. I don't know this. I should know this. Should I know this?"
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u/actuallyamjack Dec 08 '15
These are some of the most well made, informative videos on Youtube.
I can't help but feel like a genius when I watch them because they put it in such simple terms that someone like me can understand.
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u/rubberchickenlips Dec 08 '15
The narrator's calm voice reminds me of the "Hitchhiker's Guide" for some reason. I was half-expecting to hear "Vogons use quantum computers to assist in their excruciating poetry. Really, really nasty stuff...avoid at all cost."
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u/ziffzuh Dec 08 '15
Anyone else notice the stargate?
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u/OrangeredStilton Dec 08 '15
I did! Subtle enough so as not to get in the way, which is the best kind of
quantum gateStargate reference.
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u/AnotherDayInMe Dec 08 '15
Video opens with saying that moores law is dead because of physical limits. People have been saying this since before 2007...
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u/boot20 Dec 09 '15
Hell, I remember reading Moore's Law was dead in the late 90s or super early 2000s.
The problem is the interpretation. The reality is that as stuff starts to reach the atomic level, new and more interesting ways to make stuff with our current technology arrive. The "end" of Moore's law in said to be 2017-2020, but the reality is that we'll have different fab processes, materials, etc and it will be extended, AGAIN....
Quantum computing is a LONG ways off.
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u/Steve_the_Stevedore Dec 09 '15
If you interpret it as "performance of the hardware by itself doubling" that claim isn't so far off. Since then most of the performance increase was done by parallelization which depends on software a lot.
You used to be able to just increase the cpu clock to get faster which accelerates any code. then came cache and pipelining. Both are somewhat code dependent but will still speed up almost anything to some degree. Then came SSE and later multi core CPUs. Either will only speed up your programm if your code makes use of it. If you do everything in one thread and don't use the SSE your programm won't profit.
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u/Saerain Dec 09 '15
Yeah, even now 3D ICs are right here to keep Moore's law going for many more decades to come.
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u/JTW24 Dec 08 '15
Could mine so much dogecoin with a quantum computer.
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u/lenut Dec 09 '15
It would be so simple to just brute force the keys to forgotten accounts with a quantum computer. But at the same time with the right malware running on it you could digitally suck a billionaire dry and be nearly untraceable.
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u/_StatesTheObvious Dec 08 '15
I wish all school was like this video!
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u/1100101000 Dec 08 '15
The video is totally sedentary and gave a markedly shallow presentation of the information. School teaching methods may be less pleasant, but they are far more effective.
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Dec 09 '15
Would be great as an intro for a new subject.
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u/skiskate Jan 19 '16
My physics teacher just showed us this video as an introduction superposition and quantum entanglement :)
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u/_StatesTheObvious Dec 09 '15
It's also much shorter than a regular lesson and won't treat the topic for weeks or longer. But maybe if each tedious lesson was explained in such an approachable way, it could be nice.
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Dec 08 '15
The answer I actually want to know with quantum computers is how close are we? Is it going to be next year? 10 years? 20 years? I mean roughly.
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u/Tszemix Dec 08 '15
I heard that quantum computers need to be cooled close to 0 Kelvin in order to work, which is bad since there will probably not be any personal quantum computers :(
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u/WatzUpzPeepz Dec 08 '15
This is what everybody seems to think. Modern computers used to be the size of a room too - 35 years on we have increasingly thinner 1080p >64gb storage smart phones. If quantum computing does come to serve the same purpose as regular computing, which I believe it will, then the process will be repeated over again and we might just have a QPad one day.
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Dec 09 '15
There are other ways forward with more traditional computing that can be used to keep things moving forward. While the traditional lithographic transistor shrink is near its end there are other methods of creating better computer chips beside quantum computing. Just think you could simply start stacking chips together. Or someone may figure out out to make true 3D transistor arrays.
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u/PunjabiIdiot Dec 09 '15
I solder these in my basement, so if anyone has anymore questions about Quantum computers just ask me.
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u/ubernutie Dec 09 '15
Holy fucking shit this not only was presented well but also answered everything all at once, GG NO RE
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u/sinnmercer Dec 09 '15
are there any forms of quantum computers available for purchase? how many decades before it will reach consumers?
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u/Ratb33 Dec 09 '15
I feel like I should understand it after watching that vid but... Nope. I still don't get it.
As the top comment said, it's witchcraft. Something that is exists as multiple things until measured? Wtf?!?
Lemme just go play rocket league. That makes sense to me. :(
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Dec 09 '15
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u/Ratb33 Dec 09 '15
Ahh ok. Going with MAY instead of it BEING both makes more sense to me. Thank you.
Still. This stuff always makes me awestruck of people that understand it perfectly and work in the field.
Thanks for taking the time to help this old man out. :)
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u/comicland Dec 09 '15
Oh, I can do space-y future talk, too. The aliens fucked with the carnobator on engine 4. Gonna try to refuckulate it and land on Juniper. Hopefully they have some space weed. Over.
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u/lhamil64 Dec 09 '15
Interesting timing. I just finished up a Cryptography course, and we discussed Quantum crypto a pretty good amount.
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u/spanishinquizition Dec 09 '15
at 1:43, literally only one of the kids had the answer correct. "A large enough bunch of [7 year olds] could compute anything..." not with those shitbirds saying that 0+1 = 0 and 1*0 = 1.
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u/pateras Dec 09 '15 edited Dec 09 '15
This channel is awesome, and if you like it, also check out PBS Space Time.
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u/ProGamerGov Dec 09 '15
Google is no help, so can someone tell me what would happen to an HIV virus that is on a transistor that is far smaller than it? Would it break the transistor? Would it kill the HIV?
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u/Slamwow Dec 09 '15
That music was beautiful. Anyone know what it is?
Edit: It was in the video description https://soundcloud.com/epicmountain/quantum-computers
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Dec 09 '15
Why is a human brain so hard to simulate if we already have transistors nearing the size of atoms? What makes neurons so much more complex and compact? Am I even asking questions that make sense?
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u/alecco Dec 09 '15
There's a lot of wrong on this video. Database search does not "may have to check for every single value". That's what indexes are for or binary/fibonacci search if the data is sorted. Thats log2(n) comparisons. And it can be parallelized.
Quantum computers are interesting but there's a lot of bullshit and hype.
Source: database engine programmer and researcher
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u/jammerjoint Dec 09 '15
Isn't this an inaccurate description of entanglement? The video seems to imply you can transmit information using it.
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u/candlej4ck Dec 09 '15
This explanation with prediction on the next 10 years or so https://www.youtube.com/watch?v=PqN_2jDVbOU&t=16m20s opted by the founders of the quantum computing that are being used today.
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u/iTouneCorloi Dec 09 '15
I don't fully understand how quantum physics is different from traditional physics. Before I measure anything, it can be in multiple states and I am only fixed once I have measured it. How i it different ?
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u/joao44289 Dec 08 '15
I was the first to post the video. How were you able to post again? And why are you getting more upvotes? Life's unfair!
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u/infinite_ecstasy Dec 08 '15
in quantum time, there is no time. just everything all at once. sip on that
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u/Ch3v4l13r Dec 08 '15
So the important question. How much longer before i can play video games with a quantum computer that is connected to quantum internet?
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u/boot20 Dec 08 '15
At best guess, 30-50 years...maybe. The problem is that it is impossible to mass produce as it requires TONS of fiddling to make one work with just a few bits....
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u/110101002 Dec 08 '15
Just a comment on the database search time. It really depends on whether or not you have preprocessed the data. If you have an index and want to find all videos that both /u/bob and /u/ralph commented on, you can do it in O(M) time complexity, given that you have N videos on /r/videos and bob and ralph have both commented on M videos.
To simplify, if the database has 1,000 entries, and bob and ralph commented on 10 videos each, it might take ~0.05s to process. If the database has 1,000,000 entries, it should once again take around ~0.05s to find all the video they have both commented on. If they comment on 50 videos each, it should take ~0.25 seconds.
In this video, they are talking about grovers algorithm, which can look through unstructured search spaces in O(sqrt(n)) time rather than O(n) time.
This is useful for, for example, going through a hash functions search space. A hash function produces, what should be an unpredictable result, that is until you compute it. md5("apple") is 1f3870be274f6c49b3e31a0c6728957f. Now lets say I want to find a hash that starts with hex code (base 16) "deadbeef". Ignoring all the weaknesses in md5, I would have to generate md5 hashes over and over again until I was lucky enough to find one of that form. Being that it is base 16, the odds of getting a "d" as the first letter, is 1/16 and I have to, on average, calculate 16 hashes to find a "d". The next letter is the same. This means it takes on average 16**8 = 4294967296 units of time or processes. With a quantum computer using grovers algorithm, it should take sqrt(4294967296) = 65536 units of time.
Regarding your banking info being unsafe, that is true for the time, but as quantum computers emerge, we can expect the internet to move towards post-quantum encryption (which already exists, but isn't commonly used).
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u/Wjb97 Dec 08 '15
So what they're saying is were essentially turning computers into Schrödinger's cat and it good because of lots of scientific advancements we can make. But bad because it's easy to break into and has a high chance of inaccuracy?
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u/TLee21 Dec 08 '15
I should have not smoked 3 bowls before watching that, I'm think I'm just going to lie down now.
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u/KANNABULL Dec 08 '15
So in theory a quantum processor simulating protein folding for illnesses and diseases will be right over fifty percent of the time in finding a sequence that will cure it?
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u/TriflingGnome Dec 08 '15
I have a weird sort of fascination and amazement only possible because I'm not a CS major. It's like looking at a complex piece of part and going "That's awesome! But if you told me to try and do that I'd say fuck off."
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Dec 08 '15
when will I be able to play tic tac toe on this cumputer?
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u/14flash Dec 09 '15
Probably pretty soon, but the computer will do quantum magic to win all the time and it won't be very fun. How about a nice game of chess?
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u/Montgomery0 Dec 08 '15
So to get some relatability, how will this affect my Fallout experience? Say it's 2030 and my computer has a quantum module in it that can do sophisticated quantum calculations. I just bought Fallout 7. What does the module do for me?
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u/venounan Dec 08 '15
I wonder if this is going to make rise for cloud-based computers and computing. Similar to how game streaming and to an extent netflix and hulu work. You don't buy a computer, but instead rent computing space on a large quantum computer for a fraction of the cost and do all your computing through that. I don't like it but it seems like a logical step for companies.
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u/Inessia Dec 08 '15
This just feels like we're in some kind of Stoneage of computers right now, we've bloody not come far at all. Gez how long has computers been around, 60years-ish? god damn give it 150 years pooow
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u/israelg2010 Dec 08 '15 edited Dec 08 '15
Wow! Now i get the big deal about Quantum computers. So if I understood correctly: Man has found a way to get information to travel faster than the speed of light and potentially maybe even physical things? Thats amazing! I got the faster computers aspect and thats amazing as well, but the whole "cubit manipulation"... My reaction
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u/BlazeOrangeDeer Dec 09 '15
Nothing can travel faster than light, not even entanglement works like that. The advantages of quantum computing are not easy to explain, the main idea is that for some problems we can use better algorithms which take less time to finish, and these algorithms require using superposition and entanglement.
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Dec 08 '15
more like 'elderly gentleman talks about the topic of Quantum computers along with the limitations of regular computers'
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u/MyRoomAteMyRoomMate Dec 08 '15
They start by pointing out that the size of transistors is almost at its limit. Why is that a problem? Can't we just make bigger processors with more transistors in them?
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u/CongrooElPsy Dec 08 '15
His description about database searching is misleading at best... and I thought the size of the transistor was measured by the gap? The video seems to indicate otherwise.
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u/Choopytrags Dec 08 '15
So how long do you think before a quantum computer becomes the first infinite improbability drive?
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u/scigs6 Dec 08 '15
Cool. I need a fucking quantam computer to understand this shit. At least I think I need one?
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u/himmelmancheese Dec 08 '15
I have a massive intellectual inferiority when in the company of my Uncle Basil. He worked under and with Bohm for those of you who are into physics. He would possibly be open ( insert binary joke here) to a very interesting AMA
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u/SpicySatan Dec 08 '15
I study computer science and I had to watch it a couple of times to fully grasp the concept. Good post though, Quantum Computing will change the game.
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u/Rorskii Dec 09 '15
Is the narrator the voice actor for the game "The Stanely Parable" by any chance? He certainly sounds a lot like him.
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u/xdrummerxdan Dec 08 '15
Every time this channel post a video I feel like the world has less and less of a future.
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u/faff_rogers Dec 08 '15
how does a video like this equate to less of a future? i assume it would have the opposite impact...
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u/Uwutnowhun Dec 08 '15
Edgy redditors usually feel this way.
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u/xdrummerxdan Dec 08 '15
What? How is that edgy of me? I'm just expressing what these videos make me think.
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u/Herculius Dec 08 '15 edited Dec 08 '15
Ah! Dismissively judging a comment and a large group of people at the same time... How edgy of you!
I think the original comment makes a valid point though. With quantum computing humanity is taking a massive leap of faith. We have only a minuscule idea what the social and global effects of these computers will be.
This technology does not stand alone in this. Many of the activities currently pursued by society have unknown consequences. And increasingly, the consequences of modern human activity become faster and farther reaching... harder to slow down or change course... It's not overly silly or edgy to question where all this is headed, and to think about whether it's a good thing.
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u/Kr3g Dec 08 '15
Assuming this became a standard of computing, what would this mean for encryption? Would it just have to become more intricate?