rotor replacement

[John J. Lee]

Paul Rubin <http://phr.cx@NOSPAM.invalid> writes:

> jjl at pobox.com (John J. Lee) writes:
> > > Building larger ones seems to
> > > have complexity exponential in the number of bits, which is not too
> > 
> > Why?
> 
> The way I understand it, that 7-qubit computer was based on embedding
> the qubits on atoms in a large molecule, then running the computation

Oh, you mean that particular kind, OK.  Doesn't apply to QC in
general.


> > > It's not even known in theory whether quantum computing is
> > > possible on a significant scale.
> > 
> > Discuss. <wink>
> 
> The problem is maintaining enough coherence through the whole
> calculation that the results aren't turned into garbage.  In any
> physically realizeable experiment, a certain amount of decoherence
> will creep in at every step.  So you need to add additional qubits for
> error correction, but then those qubits complicate the calculation and
> add more decoherence, so you need even more error correcting qubits.

Yes, that's much more interesting, dunno what the current state of
play is.

[...]
> I'm not any kind of expert in this stuff but have had some
> conversations with people who are into it, and the above is what they
> told me, as of a few years ago.  I probably have it all somewhat garbled.

Me too :-)


John