[Havoc]

>For beginners, he says, an actual D-Wave device isn’t even necessary.

I find this somewhat surprising.

If you think of AI code designed for GPUs, there I can see "yeah you can practice on a CPU". It'll suck but it'll work.

For quantum tech the entire sales pitch is that it's fundamentally different...doing what's near impossible on conventional hardware.

Yes I realise he's talking about the library so annealing on a CPU I guess but still seems like a very strange comment in this context.

[krastanov]

"Quantum tech" is regrettably much too overloaded of a term.

The "quantum annealers" that D-Wave sells are not known to be more powerful than classical computers. For the moment, at best, they are interesting analog computers.

Quantum computers (either the circuit model or equivalently the quantum adiabatic computer model) are conjectured to be much more powerful than classical computers, but they are quite a bit different from D-Wave's quantum annealers (for starters, they are supposed to be able to keep all their qubits in a pure entangled state, which D-Wave definitely can not do). There are various experimental hardwares that are able to keep a handful of qubits entangled, but we will need thousands (if not millions) before being able to do anything useful with them.

[ben_w]

If I understand correctly (which is a big if given it is quantum mechanics), any quantum algorithm can be stimulated on a non-quantum computer, but doing so has an exponential penalty.

[lisper]

Exactly right.

[zaroth]

I think the performance of the actual device is so limited it’s like running an iPhone simulator to debug your software.

But if the expected performance of the quantum machine is theoretically going to increase exponentially every X months for the next 2 decades, combined with the theory that certain problems shift from exponential to polynomial time solutions, yes, eventually the “debugger” will not be useful to actually try running your solver.

[jcoffland]

But quantum computing performance hasn't increased exponentially in the last X months.

[empath75]

Everything I’ve read says that the d-wave isn’t a real quantum computer.

[archgoon]

This is basically correct.

When people talk about "Quantum Computers" that can factor large primes, they are referring to a Universal Gate Quantum Computer. As of today, the largest Universal Gate Quantum Computer has 72 qubits.

The DWave Quantum Annealers are essentially a special purpose device that performs Quantum Annealing. What they refer to as 'Qubits' are very different from the entangled Qubits of a Universal Quantum Computer. To the best of my knowledge (and the paper explicitly distinguishes between the two types), it has yet to be demonstrated that Quantum Annealing is equivalent to Universal Gate Quantum Computer (and is generally suspected not to be), is in it's own complexity class, or even if it provides any complexity speedup over classical computers.

[garmaine]

There isn’t a universal quantum computer in the sense that there is a universal Turing machine for classical computation. All quantum computers are special purpose circuits, not general logic machines.