qml.sample¶
-
sample
(op)[source]¶ Sample from the supplied observable, with the number of shots determined from the
dev.shots
attribute of the corresponding device.The samples are drawn from the eigenvalues \(\{\lambda_i\}\) of the observable. The probability of drawing eigenvalue \(\lambda_i\) is given by \(p(\lambda_i) = |\langle \xi_i | \psi \rangle|^2\), where \(| \xi_i \rangle\) is the corresponding basis state from the observable’s eigenbasis.
Example:
dev = qml.device("default.qubit", wires=2, shots=4) @qml.qnode(dev) def circuit(x): qml.RX(x, wires=0) qml.Hadamard(wires=1) qml.CNOT(wires=[0, 1]) return qml.sample(qml.PauliY(0))
Executing this QNode:
>>> circuit(0.5) array([ 1., 1., 1., -1.])
- Parameters
op (Observable) – a quantum observable object
- Raises
QuantumFunctionError – op is not an instance of
Observable
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