> That brings me to a question: What do we need for quantum-writable
> memory? Anything exotic? And by the way, why do we need (say) 45
> qubits to factor a 15-bit number? Shouldn't 15 qubits be enough to test
> every possible divisor of a 15-bit number?
Quantum-writable memory: it should retain its coherence for a long time,
but according to Science, plain atomic nuclei will do quite well for this.
If we can add quantum error-correction, then we will have indefinite
storage. Maybe something like an array of atoms that are refreshed
regularly.
Shor's algorithm doesn't test every divisor, it uses a quantum fourier
transform to find periodicities of x^a mod p. I assume this is why it
need 45 qubits.
-----------------------------------------------------------------------
Anders Sandberg Towards Ascension!
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