# How to reset classical register on QISKit

I want to do a feedforward on a quantum circuit using the simulator of Qiskit.

For example, measure qubit_1 to bit 1 and do some operator on qubit_2 if the result of measuring qubit_1 is 0 and if the result is 0, then another operator. Then measure qubit 3 and do some operator on qubit_4 if the result of measuring qubit_3 is 1.

so far I know that I could use

QuantumCurcuit.operator(Quantumregister[index]).c_if(classicalRegister, value)


But the condition of c_if is depended on all value of all bit of classical register. I want to do feedforward depend on an individual bit just 0 or 1.

I think it is not the right way to solve the issue by adding another addition qubit to be $$|0\rangle$$ and project it on the classical bit. Just to reset that bit to 0 again this way.

So is there any way to reset the classical register?

The c_if in Qiskit only operates on a full classical register, following the OpenQASM spec. If you would like to condition on individual bits, you have to create a new ClassicalRegister for each bit. Then you can condition on each bit separately.
• Yes, that is a reason why I use c_if to do this job. – Poramet Pathumsoot Jul 15 at 14:39