3 ms·
Is that a legitimate analogy? My understanding is that the number of qbits of a quantum computer are not fairly compared to the number of classical bits needed
by gfodor 9y ago
Is that a legitimate analogy? My understanding is that the number of qbits of a quantum computer are not fairly compared to the number of classical bits needed in order to make a useful computation.
- PeterisP 9y agoIt's even more limiting. A 5 qubit computer can get the expected efficiency of a quantum algorithm that needs a working memory of less than 5 qubits. That's it. Furthermore, the scaling is entirely different - a 8 bit computer can simulate 16-bit calculations with a limited number of primitives - e.g. a 16-bit multiply can be made with four 8-bit multiplies; but the quantum operations don't stack that way; you have to "read" the values in between, collapsing all the quantum states. So for quite a few algorithms there are no efficient ways to stretch the size limit, you're back to brute force. If you have a quantum computer that allows you to e.g. break a 128 bit keys, then factoring a 129 bit key takes twice as much time, a 130bit key takes four times as much, and a 256 bit key takes 2^128 times as much time.