I'm generating a qiskit circuit and want to add an X gate to a qubit if the sum of some previous measurements modulo 2 is equal to 1. In cirq, I could just use a sympy expression that would look something like X(q(10)).with_classical_controls(Mod(q1 + q4 + q7, 2)), where q10 is the qubit I'm applying the X correction to, and q1, q4 and q7 are the measurement who's sum I'm using to control this correction. How can I do this in qiskit?

  • $\begingroup$ As far as I know, this is not possible in qiskit. But I would be very happy to be corrected on that. I faced a similar problem with classical control and kind of solved it with an ugly workaround: quantumcomputing.stackexchange.com/questions/38188/… (but I guess that is not what you are looking for) $\endgroup$
    – qubitzer
    May 15 at 9:22
  • 1
    $\begingroup$ You can implement sum modulo 2 by XOR'ing the bits. Here you can find how to do this with Qiskit dynamic circuits. $\endgroup$ May 15 at 9:54


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