qml.debug_tape

debug_tape()

Access the tape of the quantum circuit.

The tape can then be used to access all properties stored in QuantumTape. This can be used to visualize the gates that have been applied from the quantum circuit so far or otherwise process the operations.

Returns

the quantum tape representing the circuit

Return type

QuantumTape

Example

While in a “debugging context”, we can access the QuantumTape representing the operations we have applied so far:

dev = qml.device("default.qubit", wires=2)

@qml.qnode(dev)
def circuit(x):
    qml.RX(x, wires=0)
    qml.Hadamard(wires=1)
    qml.CNOT(wires=[0, 1])

    qml.breakpoint()

    return qml.expval(qml.Z(0))

circuit(1.23)

Running the above python script opens up the interactive [pldb] prompt in the terminal. We can access the tape and draw it as follows:

[pldb] t = qml.debug_tape()
[pldb] print(t.draw())
0: ──RX─╭●─┤
1: ──H──╰X─┤

code/api/pennylane.debug_tape

 

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