Let’s consider that i encoded my data into a quantum state like this: U|0> = |psi>. Finally, i want to design a Hadamard test classifier.

. My goal is to calculate inner product between quantum state for train and quantum state for test data: like this <psi|phi>. i know i can do it with swap test. i want to check with Hadamard test as well.

Hi @sassan_moradi,

It seems that you’d be on the right track, having the train and test data prepared at the beginning of the circuit could be a nice start. Was there perhaps a part of using PennyLane to implement the Hadamard test that you found challenging where we could try helping?

i need to implement the controlled unitary by Pennylane. i know how to use block encoding to define a controlled unitary. But for having 5 qubits i need to define a 32*32 which is tedious. Is there an another method to implement an arbitrary single controlled operation?

You might want to take at the `ControlledQubitUnitary`

operation or the `ctrl`

transform.

Hope those help

thanks Christina. it worked.

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