Maybe a stupid question but does anyone here know how quantum computing would effect bitcoin/crypto in general?
Quantum Computing Explained
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Re: Quantum Computing Explained
#32IBM lets you poke around one of their quantum machines here for free: https://quantumexperience.ng.bluemix.net/qx/experience They also include a brief tutorial on how to program for it too.
AFAIK this is a simulation, not real quantum machines.
Re: Quantum Computing Explained
#33Will quantum computing kill Bitcoin by rendering the underlying cryptography obsolete?
I understand there are two ways Bitcoin is affected by a crypto quantum-computer: 1) A QC is able to derive the private-keys for a wallet's public address, allowing for the theft of bitcoin 2) A QC able to perform the proof-of-work algorithm to mine new blocks at an order-of-magnitude faster rate than currently possible. Fortunately for 1) (I think) it currently takes 2^512 (?) operations to break the private/public…
> Fortunately for 1) (I think) it currently takes 2^512 (?) operations to break the private/public algorithm which is unfeasible to brute-force on normal hardware but a QC brings it down to 2^128
Where have you got that info? Quantum computers can break ECDSA in polynomial function of 512.
> the blockchain could be changed overnight to use a new keying algorithm.
How?
Re: Quantum Computing Explained
#34Earlier quoted context omitted.
Does not matter whether it is electric or photonic (and many systems are in between). Scalable error correction (i.e. the error approaches zero in the limit of a large system) is possible only with digital systems, whether classical or quantum. There are things we can do to suppress errors and make a slightly bigger analog computer (classical or quantum) but there is no way to make an analog system scalable (i.e. not…
Have you ever heard the expression if an expert tells you something can be done, s/he's prolly right. If s/he tells you it can't be done it's not quite certain. Im not convinced that our understanding is quite there to say it can or can't be done.
If your only response to a reasoned argument is a dubious aphorism, you’ve already lost the discussion. You are literally just arguing from disbelief.
Re: Quantum Computing Explained
#35IBM lets you poke around one of their quantum machines here for free: https://quantumexperience.ng.bluemix.net/qx/experience They also include a brief tutorial on how to program for it too.
AFAIK this is a simulation, not real quantum machines.
They have both a simulator and real machines you can use. The "ibmqx5" is a 16-qubit device. The problem is that noise rates are very high. For example, just to swap two adjacent qubits (using three CNOT gates), it looks like you will incur at least 10% error. It is hard (though not impossible) to run meaningful experiments on such a noisy system.
Re: Quantum Computing Explained
#36Quantum computing is way beyond me but I found this video by Kurzgesagt really interesting https://youtu.be/JhHMJCUmq28
Re: Quantum Computing Explained
#37So take what I'm about to say with a grain of salt but I believe that current generation of quantum computers (quantum digital) is fundamentally flawed. Basically all architectures I've seen still use bits (qubits are still bits and use entanglement) as opposed to the superior signals. The class of computers I'm talking about is called continuous-variable quantum computers ( https://en.wikipedia.org/wiki/Continuous-v…
Terry Rudolph has an excellent paper arguing for continuous-variable quantum computers [1]. CV still uses entanglement. You can think of CV states as infinite dimensional qubits. So in a way it is still "digital". Something about quantum measurement is fundamentally digital.
Re: Quantum Computing Explained
#38Earlier quoted context omitted.
AFAIK this is a simulation, not real quantum machines.
They have both a simulator and real machines you can use. The "ibmqx5" is a 16-qubit device. The problem is that noise rates are very high. For example, just to swap two adjacent qubits (using three CNOT gates), it looks like you will incur at least 10% error. It is hard (though not impossible) to run meaningful experiments on such a noisy system. https://quantumexperience.ng.bluemix.net/qx/editor
Oh, thanks. You are correct that it is very noisy. Just a single CNOT is giving me 15% error.
Re: Quantum Computing Explained
#39Whatever you do, don't invest in quantum computing.
Re: Quantum Computing Explained
#40Maybe a stupid question but does anyone here know how quantum computing would effect bitcoin/crypto in general?
Unless you can find a way to implement a way to reverse a hash efficiently using a quantum algorithm, I wouldn't hold my breath.