Does quantum mechanics invalidate hard determinism?

no

A few things:
- My understanding is the jury is out as regards quantum indeterminacy, there are some scientists who believe it is deterministic and we just can't quite grasp how yet.
- Even if things are inderministic at the quantum level, they seem to be deterministic at the macro level
- Even if the indeterminism at the quantum level does introduce an element of randomness in human choice, could that really be called "free will"?

No

The "indeterminism" of QM is completely a matter of interpretation rather than science. The actual science--namely the math that models quantum systems--is inherently deterministic. The matter of interpretation is over why we experience its results indeterministically. If we assume that we're a quantum system obeying the same laws as particles, then it turns out the indeterminism is merely a matter of our limited perspective, rather than something that's inherent on the quantum level. With that interpretation, quantum mechanics becomes deterministic (and local, and real; most indeterministic interpretations are non-local and non-real). For QM to invalidate hard determinism, one of the indeterministic interpretations would have to be proven correct, and right now the evidence (and Occam's Razor) is against them. 

I pretty much agree with what Kiera said here: imdb2.freeforums.net/post/506365/thread minus the last sentence. I also agree with Yudkowsky (surprise) and his lengthier solution in a series of posts here: wiki.lesswrong.com/wiki/Free_will_(solution)

EDIT: In that Yudkowsky sequence, if you don't want to read it all, I highly recommend the "Thou Art Physics" article. This is where I think people go MOST wrong in addressing this question, by starting with the assumption that, to paraphrase Yudkowsky, "you" and "physics" are competing to determine the future, as opposed to "you" (and, by extension, your will) being what desires/acts inside of physics. Ironically, what he says in that article also summarizes what I wrote about QM and determinism: "it requires constant vigilance to maintain your perception of yourself as an entity within physics... You will recall that it is this point which I nominated as having tripped up the quantum physicists who failed to imagine macroscopic decoherence; they did not think to apply the laws to themselves.
"

You don't need consensus because I'm correct here. QM can't invalidate hard determinism until an indeterministic interpretation is proven right. 

If you knew anything about me you'd know it's very unusual for me to make such claims, and that I don't make them lightly.

Just to elaborate (for you or anyone else who's interested): Fundamentally, quantum systems are modeled by a single deterministic equation, the Shrodinger Wave Equation, and indeterminism only comes into play when we try to measure the precise position and/or momentum of a particle. Hence the "measurement problem" and hence the reason for differing interpretations. Copenhagen's interpretation--which states the wave function of particles is unreal, and that observation/measurement causes it to collapse--is the most famous (probably because it was the first), and because it was indeterministic the association of indeterminism with QM stuck. However, there's no real justification for Copenhagen's assumption of a causal collapse; it just adds an extra element and needlessly complicates QM (Occam disapproves). If you take the Shrodinger Wave Equation and apply it to all levels, you get determinism, locality (no "spooky action at a distance," which bothered Einstein), and realism (the lack of which also bothered Einstein: "you mean to tell me the moon doesn't exist if nobody's looking at it?"). Any indeterministic interpretation must add something that is currently neither justified mathematically nor empirically. 

So anyone who wants to claim that QM invalidates hard determinism is going to have to argue why they think any of the indeterministic interpretations are more likely, and I'm betting you won't get any takers here. 

It's incomplete and misleading. It's only accepted as a probability distribution by those that agree with Copenhagen, though all experimental physicists (as opposed to theoretical physicists) would treat it as a probability distribution in order to do the math. 

Think of it like this: you have a line of gunpowder that's been lit that, at some point, will fork into three different paths. You (the scientist/observer) are the fire, gunpowder is the wavefunction. Before you hit the fork (which happens when you measure), you want to know what the probability is of going left/middle VS right. The Shrodinger Wave Equation says you will go all three, but it also says that you will find yourself left/middle VS right (once you've already split) 66% of the time. Now, would you describe this situation as deterministic, probabilistic, or both? 

The Shrodinger Wave Equation essentially says "the particle goes all ways." Human wants to know "what's the probability I will measure it going one way or the other?" The Shrodinger Wave Equation can also tell you that, and since that's typically what we want to know (since this is where the predictive power of QM comes from), that's why it's treated as indeterministic, even though it's only indeterministic from our perspective. In order to make the actual wavefunction probabilistic you have to assume that the other "ways" don't actually exist and our measurement causes it to only go one way. 

Yes, they entail spooky action at a distance under the Copenhagen interpretation, which is a crucial point that the vast majority of such articles leave out. If anything, the closing of the Bell loopholes is more reason to ditch collapse interpretations all together since this will mean QM being fundamentally incompatible with General Relativity. Einstein was right to question collapse interpretations, but was wrong about the reasons why. He thought there were hidden variables, but Bells Theorem (and the continued closing of the Bell loopholes) is ruling out hidden variables as a possible explanation. 

What you say about quantum computing is correct, but the reality of the superposition is precisely what Copenhagen (and most indeterministic interpretations) dispute. If superposition is real and applies at all levels, then that's when you get determinism, because it means the Shrodinger Wave Equation applies at all levels. 

There's no doubt that Occam favors determinism because the simplest interpretation of QM is to take the Shrodinger Wave Equation at face value, as an accurate representation of something that's real. If you do that you get determinism, even though we can never measure/experience it as in classical physics. 

I'm saying it's still unclear to scientists what the Schrodinger equation means ontologically, hence one reason for the differing interpretations.