mindquantum.core.circuit.partial_psi_psi

mindquantum.core.circuit.partial_psi_psi(circuit: Circuit, backend='mqvector')

Calculate the following value of the given parameterized quantum circuit.

\[B_i = \frac{\partial \left<\psi\right| }{\partial x_i}\left|\psi\right>\]

Parameters

• circuit (Circuit) – A parameterized quantum circuit.

• backend (str) – A supported simulator backend. Please refer description of Simulator. Default: 'mqvector'.

Returns

Function, a function that can calculate inner product of partial psi and psi.

Examples

>>> import numpy as np
>>> from mindquantum.core.circuit import partial_psi_psi, Circuit
>>> circ = Circuit().rx('a', 0).ry('b', 0).rz('c', 0)
>>> ppp = partial_psi_psi(circ)
>>> ppp(np.array([1, 2, 3]))
array([0.+0.j        , 0.-0.42073549j, 0.-0.11242255j])