4 ms·

I never had seen the scaling 2^(n^2) before. Can you provide a reference for that? I am also don't understand the point of simulating noise correctly. If you g

I never had seen the scaling 2^(n^2) before. Can you provide a reference for that? I am also don't understand the point of simulating noise correctly. If you get the result from computation on some vendor black-box black box quantum computer can you really know with what type of noise you would have obtained the result? Another skepticism about the hype is that the result of quantum computation is just a matrix product on initial state from predefined gates. It is just linear algebra on large unitary matricies. Nothing quantum about it.

doubleunplussed 5y ago
They're talking about propagating a density matrix instead of a state vector. If you're not familiar, a density matrix is an n x n matrix where n is the number of elements in the corresponding state vector, and contains information akin to a probability distribution over state vectors. However, actual quantum computers propagate state vectors, not density matrices, as far as I know. You'd need to run it a large number of times, or have a large ensemble of identical sets of qbits being propagated with the same algorithm to need a density matrix to describe it, I would have thought. So saying you'd need to simulate a density matrix to simulate a quantum computer confuses me. I know quantum physics but not quantum computing specifically, so I could be wrong - the grandparent comment sounds like they know what they're talking about otherwise.