That's so distracting, I had to listen to it again to hear the actual question :-)

@@robinw77 He basically is, he knows the question being asked and has already formed his answer in his head. Now he's just waiting for the other person to finish speaking. Definitely comes off as rude and distracting though.

@@cameronl1859 If only people around understood that.

It's all about statistics it seems. You figure out what it should do, then calibrate and test till it does what you want so you can predict it's behavior in the future.

There's a huge difference between following along and actually doing it tbh

By the end of the video it *seems* like you can essentially set up the qbits in such a way as to perform entire calculations that would, on standard computing hardware, take hundreds or thousands of independent operations in just a couple of operations.... at least that's my takeaway anyways, lol.

Agreed, Copenhagen Interpretation is pure lunacy. Pilot wave FTW

That's what's called a well meant unsatisfactory explanation.

you beat me to it :D

qubits*

regardless they seem to have collapsed to 0% probability of being viewable =(

nope.. why

how to "Hello world!" with a Quantum Computer, as it were

Same

Your analogy would be quite apt for adiabatic quantum computing, not exactly for superconducting qubit version which Rigetti is building.

I mean, if you look at the X86 instruction set, "infinity" definitely comes to mind.

really ?

I believe he meant there is an infinite number of options if you are designing a chip. Not a teacher material.

Lol x86 is hilarious. Apparently the mov instruction is Turing complete, someone make a C compiler that only used that 1 instruction. Can't wait until apple moves macOS to ARM.

Turing complete... a single opcode ?

H 0 CNOT 0 1 MEASURE 0 [0] This is a program that will apply the Hadamard gate on qubit 0, a CNOT gate on qubits 0 and 1, and a MEASURE instruction on qubit 0, putting the "answer" into classical register 0. This is a program to randomly flip a coin. In the classical register 0, we will, 50% of the time, have a 0, and 50% of the time, a 1.

The problem might be that the way it seemed to be explained in the video you are not measuring a value and getting something x% of the time but instead you are measuring the qbit you know to be a specific value and collapsing the probability to a single predetermined combination.

Draugo You measure a particular qubit, but you do not know its value. That’s exactly what’s determined by the probability.

But it was stated in the video that you already know the probabilities then what is gained by running the calculation and measuring a qbit a multitude of times? You get values that reflect the known probabilities. Or if you don't know the probabilities then is the point to find them out by statistics? Then what does a qbit do that a gpu doesn't since they are especially build to do matrix operations?

In case of small quantum computers, sure, you know the probabilities. But when you have more than few dozens qubits, then the only place you can store those probabilities in a useful way... is the quantum computer itself. For example, if you have 50 qubits and probability is stored classically as an 8-byte complex floating-point number, you need 9 petabytes just to store those probabilities, and updating them according to calculations would take quite a long time.

it's about the speed, not the steps

@@RandomNullpointer Doesn't less steps equate to a faster executed algorithm though ?

Not necessarily, because quantum weirdness count as “parallel” instructions

Quantum FT doesn't offer a speedup as compared to regular FT. But it's a key intermediary step for algorithms like Shor's that actually do provide that quantum-y speedup!

hes doing a verbal handshake to show that hes received the information

aggressive verbal handshake tbh

VERY aggressive hahaha

hmh

mhm

I agree. How about showing us the code to factor a 4 bit number?

Gil Kalai refuted quantum scaling, basically refuted quantum computing in general, by showing that adding qubits needs increasingly more qubits for error correction, and that no: they won't be able to reduce the noise enough.

@@jmccallister-rc5dy And yet, here we are cutting around the edge. Reducing the noise is a physical problem and mathematically is not limited any further than physics do. So it's really just a matter of going down and down on the details and improving precision and so on and eventually it will not only be sufficient but far much better than we've ever though it could be done. It's scaling physical scaling, it's not mathematical where you bump on literal impossibilities.

@@robertthompson7059 It likely means that we won't see scaling comparable to semiconductors the last few decades, but rather incremental upgrades to the number of stable/useful qbits in quantum computers.

Guess we are in the same boat (-;

Same exact sentiment. Saw this and thought why an i not subbed already.

Miguel Martin algorithms need to make use of quantum interference similar to the patterns produced by Young's double slit experiment (google that first if not familiar with it). the spacing between the slits causes the patterns to be compressed / spread out. if you focus on a single point on the screen, the probability of a photon landing there depends on the angles of the beams. a single slit wont have any interference patterns. quantum computers make use of that interference, not just between 2 but all of its qubits. algorithms are needed (these make use of very complicated maths) to make use of quantum interference with probabilities to determine of the answer is yes or no. you cant step through each operation like you can with maths, so they gotta trust that the algorithm and the maths behind it is correct. it wont be able to run normal algorithms with no quantum interference. the speed up is not running normal things faster, but rather running things in a completely different way

Searching in huge array using boolean logic you need to parse the whole array one by one and you need to make N checks. Using quantum login you can find an item in square root of N checks. Check Grover's algorithm. Easy as that :D

QM has no low hanging fruits. I took the online version of MIT's 8.05x (advanced QM) from EdX, in the final notes prof. Zweibach recommended a pile of books for further reading by adding, that once you have mastered them you can do actually something useful with QM.

It works like jepardy. You put in a answer to a matrix question, and the quantum computer give you the original statement... This is very usefull for example if you have a file that is cryptated. If you have sufficent data you can break the crypty because the quatum computer don´t have to try every single code.. well... it kind of tries every single one at the same time

Q-computers can solve all problems usual computers can solve in the same order of time.

t. brainlet

@Bobbito Chicon Damn dude, pass some of whatever you're smoking

I thought is was very succinct, given that its for a broad audience of tech enthusiasts.

@Bobbito Chicon this guy's got the idea.

(Added More) Multiple Dimensions is not at all an accurate way of stating it- coupled degrees of freedom, continuous across time but discrete in space (quantized AKA QUANTUM things are discrete objects) ... also people rarely point this out but a dimension parallel to itself is CATEGORICALLY the same dimension- dimension implies orthogonality

Android480 Mhm, mhm...mhm...

Yeah, I did not understand the instructions at all, which is frustrating because not knowing what they do prevents me from wrapping my head around how this all works and is used.

Time to learn about this thing called google. (You can search for the matrix representation of all the gates)

Thanks Robert.

They are not more powerful (in a sense that anything QC can compute, TM can do too). However, there is a subset of NP problems which QC can compute in polynomial time. In other words, they are faster. In practice, QCs are more powerful, because you can build a QC that can solve stuff, that would require classical computer bigger than the observable universe.

Nah, QPUs aren't faster for general matrix operations than classical computers are. This is a myth. You also need to consider that all known quantum matrix multiplication algorithms do have errors associated with them both in terms of state preparation and readout. States also need to be prepared classically, which can be done efficiently in some cases but not in general. I'm not saying there won't be any applications in that field, but a lot more basic research is required to determine whether it's even worth pursuing that route. Not only do matrix multipliers require a lot of qubits, the associated gates are complicated and the algorithms are not very fault tolerant.

Anyone with a link can watch an unlisted video. Private videos require direct invitations.

The problem is there's no way to show you how quantum computers actually work without getting very involved with complex vector spaces.

You don't need to get that involved to understand how the logic of a quantum computer works. Although getting a quantum computer to work gets pretty involved. In the video he showed it solving a real problem. One instruction affects a set or column of probabilities. qbits can be entangled thus allowing for fairly complex optimizations and of course factoring which is why its talked about in relation to encryption as most encryption is based on the factoring problem.

I totally understand that (Chris's) feeling. I remember feeling it when I learnt my umpteenth language. And getting to know computers at all. And every new concept maths could throw at me. But after a while you figure out that it's not a productive thought process

I get the feeling he left out some important context.

chris4072511 12:50

Yes you have not bed fed by the algorithm. You have been fed by humans that love algorithms!

Sadly, not in the general case. Which is weird - quantum computers essentially are giant matrix multiplication machines where the gates form a huge nxn matrix and the quantum state is a vector of length n. But the problem is the matrix has to be unitary, and also that the quantum state can never be observed directly (it always collapses into one of the basis states). So while the linear algebra representation of the quantum computational model is exactly the problem of multiplying matrices and vectors, it's actually pretty terrible at doing that. On the other hand, if you can keep multiplying a vector by a unitary matrix and eventually find a vector with a very large value for one of the basis states and small values for every other state, the exact series of matrices to multiply by is the quantum algorithm, and you've done something useful.

Usually it's microwave pulses hitting ions in an quadrupole ion trap, which uses rapidly changing electric fields to hold an ion in place. Lasers send electromagnetic radiation at the ion. Depending on the phase, frequency, and duration this pulse can change the quantum state. If you think of a quantum state as an arrow in a sphere, where the north pole is one state and the south pole is another, then a pulse can cause the arrow to 'rotate' within the sphere. Depending on the phase and frequency, it will rotate along a different axis and/or rotate at a different 'rate'. I know that's a bit handwavy - the correct term there is the electromagnetic wave causes a specific "magnetic dipole transition" on the particle representing a qubit. You can use a microwave pulse on two qubits to entangle them, essentially causing their quantum states to become correlated with each other. In the computational model here, any two qubits can be entangled. In a real one, there are specific pairs that can be entangled, and only in one direction. It's still a universal quantum computer; there is some mathematics to ensure that a quantum algorithm can always be converted into the weird model of 'only some pairs can be entangled'. You can measure a qubit by using a microwave pulse tuned such that it couples with only one basis state, essentially collapsing it then "testing" whether the qubit is in that state. The qubit either becomes excited and releases some measurable photons, meaning it collapsed into that state, or doesn't become excited, in which case it collapsed into the other state.

PPU 😄