- Graph.time_evolution_operators_pwc(hamiltonian, sample_times, *, name=None)
Calculate the unitary time-evolution operators for a system defined by a piecewise-constant Hamiltonian.
hamiltonian (Pwc) – The control Hamiltonian, or batch of control Hamiltonians.
sample_times (list or tuple or np.ndarray(1D, real)) – The N times at which you want to sample the unitaries. Must be ordered and contain at least one element.
name (str or None, optional) – The name of the node.
Tensor of shape
(..., N, D, D), representing the unitary time evolution. The n-th element (along the -3 dimension) represents the unitary (or batch of unitaries) from t = 0 to
- Return type:
For more information on Pwc nodes see the Working with time-dependent functions in Boulder Opal topic.
Simulate the dynamics of a single qubit, where a constant drive rotates the qubit along the x-axis.
>>> initial_state = np.array([1, 0]) >>> sigma_x = np.array([[0, 1], [1, 0]]) >>> duration = np.pi >>> hamiltonian = graph.constant_pwc_operator(duration=duration, operator=sigma_x / 2) >>> graph.time_evolution_operators_pwc( ... hamiltonian=hamiltonian, sample_times=[duration], name="unitaries" ... ) <Tensor: name="unitaries", operation_name="time_evolution_operators_pwc", shape=(1, 2, 2)> >>> result = qctrl.functions.calculate_graph(graph=graph, output_node_names=["unitaries"]) >>> result.output["unitaries"]["value"].dot(initial_state) array([[5.0532155e-16+0.j, 0.0000000e+00-1.j]])
See more examples in the How to simulate quantum dynamics for noiseless systems using graphs user guide.