Multi-qubit gates

[dssikdar]

For multi-qubit gates, the coding/realization becomes tricky. This is fair game to work on.

[dssikdar]

I was thinking that since each qubit is accessed by its position, we can just concatenate their states to make a longer vector. Then, we do the similar matrix multiplication with the gate matrix (now 4x4) and return the new quantum statevector. We can then redistribute it to the corresponding qubits' states.