constant_pwc_operator

Graph.constant_pwc_operator(duration, operator, *, name=None)

Create a constant piecewise-constant operator over a specified duration.

Parameters:

duration (float) – The duration \(\tau\) for the resulting piecewise-constant operator.
operator (np.ndarray or Tensor) – The operator \(A\), or a batch of operators. It must have at least two dimensions, and its last two dimensions must be equal.
name (str or None, optional) – The name of the node.

Returns:

The constant operator \(t\mapsto A\) (for \(0\leq t\leq\tau\)) (or a batch of constant operators, if you provide a batch of operators).

Return type:

Pwc

See also

Graph.constant_stf_operator: Corresponding operation for Stfs.
Graph.hermitian_part: Hermitian part of an operator.
Graph.pwc_operator: Create Pwc operators.

Notes

For more information on Pwc nodes see the Working with time-dependent functions in Boulder Opal topic.

Examples

Create a Hamiltonian from a batched constant operator.

>>> sigma_x = np.array([[0.0, 1.0], [1.0, 0.0]])
>>> sigma_z = np.array([[1.0, 0.0], [0.0, -1.0]])
>>> batched_operators = np.asarray([sigma_x, sigma_z])
>>> graph.constant_pwc_operator(duration=0.1, operator=batched_operators,  name="op")
<Pwc: name="op", operation_name="constant_pwc_operator", value_shape=(2, 2), batch_shape=(2,)>
>>> result = bo.execute_graph(graph=graph, output_node_names="op")
>>> result["output"]["op"]
{
    'durations': array([0.1]),
    'values': array([
        [[[ 0.,  1.], [ 1.,  0.]]],
        [[[ 1.,  0.], [ 0., -1.]]]
    ]),
    'time_dimension': 1
}

See more examples in the How to represent quantum systems using graphs user guide.