3
votes
3answers
360 views

What is the next step beyond quantum computation?

Assuming we develop quantum computers one day, what would be theoretically the next step? Would it be string-theory based computers? How would these computers differ performance-wise (ie what can they ...
1
vote
2answers
175 views

Quantum XOR: How do you generalize it?

Consider the classical XOR Gate: Given a 2 bit system: $G = [u_1, u_2]$ $$XOR(G) = (u_1 + u_2) \ mod \ 2$$ Is the following a good generalizaiton of a Quantum XOR Gate: Given a 2-qubit system: ...
9
votes
1answer
221 views

Computability of physics

As far as I understand a Universal Quantum Simulator can simulate any quantum system and thus anything that exists in the universe. Also, a quantum computer can implement such a quantum simulator. ...
13
votes
2answers
1k views

How many qubits are needed for useful computation?

Seeing the news about 14 entangled states today @ Innsbruck: I haven't found a clear guide online to how many qubits we are aiming for a first practical quantum computer, e.g. Factorization, Search ...