# Tag Info

### How to estimate Qiskit circuit runtime before sending to run on IBM real quantum device?

You can try to use Qiskit pulse, see: https://qiskit.org/textbook/ch-quantum-hardware/calibrating-qubits-pulse.html#4.2-Measuring-$T_2$-using-Hahn-Echoes- Based on https://quantumcomputing....
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### How can I write if conditions on quantum registers using qiskit

If "some operations" in your question means quantum operations, then you can use Gate.c_if() to apply a gate based on a value in a classical register as ...
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### QV circuits fail to execute in real devices

As per Qiskit's release notes, under "IBM Q Provider 0.12.0"[1] qiskit.providers.ibmq.IBMQBackend.run() method now takes one or more ...
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### QV circuits fail to execute in real devices

By doing some error tracking, you'll find that TypeError: 'QasmQobj' object is not iterable` was raised from ...
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### Can someone explain to me what is T gate and tdg like im five?

tdg is the method used to apply $T^\dagger$ (read T dagger). Thus, there are no differences between these two. For a quantum gate $U$, $U^\dagger$ is the inverse of ...
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### Hadamard on first qubit for two qubit state doesn't output what it should on Qiskit

This is because Qiskit uses little-endian[1] for bit ordering. So, $|01\rangle$ means that first qubit in the state $|1\rangle$ and second qubit in the state $|0\rangle$. For more details see the ...
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