Bitcoin Forum

Effectively, it can try all possible solutions at the same time and then select the best.

http://www.bbc.co.uk/news/science-environment-22554494#TWEET758009

i wonder if this monster can handle a 51% bitcoin attack?

Whos going to have the money to spend 15 mill on a computer?

Whos going to have the money to spend 15 mill on a computer?

They are probably based on normal processors and thus they will suffer from the same limitations. That beast will probably mine about as fast as a few good graphics cards at most.

not sure

Quantum computing is based around exploiting the strange behaviour of matter at quantum scales.

Most work on this type of computing has focused on building quantum logic gates similar to the gate devices at the basis of conventional computing.

But physicists have repeatedly found that the problem with a gate-based approach is keeping the quantum bits, or qubits (the basic units of quantum information), in their quantum state.

"You get drop out… decoherence, where the qubits lapse into being simple 1s and 0s instead of the entangled quantum states you need. Errors creep in," says Prof Alan Woodward of Surrey University.
One gate opens...

Instead, D-Wave Systems has been focused on building machines that exploit a technique called quantum annealing - a way of distilling the optimal mathematical solutions from all the possibilities.
Geordie Rose, D-Wave Geordie Rose believes others have taken the wrong approach to quantum computing

Annealing is made possible by physics effect known as quantum tunnelling, which can endow each qubit with an awareness of every other one.

"The gate model... is the single worst thing that ever happened to quantum computing", Geordie Rose, chief technology officer for D-Wave, told BBC Radio 4's Material World programme.

"And when we look back 20 years from now, at the history of this field, we'll wonder why anyone ever thought that was a good idea."

Dr Rose's approach entails a completely different way of posing your question, and it only works for certain questions.

Quantum computer's would destroy bitcoin and possibly be able to decrypt public address hashes theoretically - if indeed this is a quantum computer.

If someone paid 15 million for it, and did run a 51% attack - bitcion would be worthless.

Say some rich guy (or Government) bought 10 or 15 of these. I bet they would be able to achieve a 51% attack.

An attacker that controls more than 50% of the network's computing power can, for the time that he is in control, exclude and modify the ordering of transactions. This allows him to:

    Reverse transactions that he sends while he's in control. This has the potential to double-spend transactions that previously had already been seen in the block chain.
    Prevent some or all transactions from gaining any confirmations
    Prevent some or all other miners from mining any valid blocks

The attacker can't:

    Reverse other people's transactions
    Prevent transactions from being sent at all (they'll show as 0/unconfirmed)
    Change the number of coins generated per block
    Create coins out of thin air
    Send coins that never belonged to him

Encryption is nearly 100% safe, even governments with billions of dollars cant crack encryptions.

Simply coding in can stop a quantum computer from even accessing encryption.