I've been reading "Programming the Universe" by Seth Lloyd, a quantum computer scientist. He goes on and on about the power of quantum computers and their ability, for example, to factor large numbers using massive parallelism. He also states that quantum parallelism is different than classical parallelism. In the quantum case, he says, the individual quantum bits (or qbits) are interfering with each other which is helpful.(adsbygoogle = window.adsbygoogle || []).push({});

A quantum computer of 4 qbits, he says, can be carrying out 2**4 or 16 tasks simultaneously. So if your trying to factor the number 20, one task might be trying out 6*3 which does not equal 20 while another task might be trying 4*5 which does.

What he does not explain is:

1) How does the Quantum Computer carry out the multiplication for a given qbit task?

2) If interference is important, then how do the separate trials interfere which each other? And how do failed tasks (6*3) interfere with the tasks which are successful (4*5) ?

3) How does the Quantum Computer know when it is done?

Any feedback on these questions would be appreciated.

Thanks,

Mike

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Quantum Computer Questions

**Physics Forums | Science Articles, Homework Help, Discussion**