Source code for openqemist.quantum_solvers.parametric_quantum_solver

#   Copyright 2019 1QBit
#   Licensed under the Apache License, Version 2.0 (the "License");
#   you may not use this file except in compliance with the License.
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#   distributed under the License is distributed on an "AS IS" BASIS,
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import abc

[docs]class ParametricQuantumSolver(abc.ABC): """Performs energy estimations for a molecule with a parametric circuit. Performs energy estimations for a given molecule and a choice of ansatz circuit that is supported by the hardware. A concrete class will contain a nested Enum class that exposes the supported ansatze to the users. The state of the class is created in the costructor so that the `simulate` function can just accept an amplitude array and return an energy. Attributes: amplitude_dimension (int): The size of the amplitudes list that should be provided to the solver. initial_wavefunction (numpy.array): The initial wavefuntion for the simulations. n_qubits (int): The number of qubits in the circuit. """ def __init__(self, molecule, anstatz, mean_field=None, backend_options=None): self.initial_wavefunction = None self.n_qubits = None self.amplitude_dimension = None
[docs] @abc.abstractmethod def simulate(self, amplitudes): """Performs an energy simulation for the given amplitudes. Args: amplitudes (list): The amplitudes to use in the simulation. Returns: float: The energy from the simulation. Raises: ValueError: If len(amplitudes) doesn't equal amplitude_dimension. """ pass
[docs] @abc.abstractmethod def get_rdm(self): """ Returns the RDM from the simulation. This is intended to be called after the simulation loop of the calling code has converged to be passed on to problem decompositions. In a concrete implementation, the `simulate` function would set the necessary internal state for the class so that this function can return the reduced density matrix. Returns: (numpy.array, numpy.array): The one- and two-element RDMs (float64). Raises: RuntimeError: If no simulation has been run. """ pass
[docs] @abc.abstractmethod def default_initial_var_parameters(self): """Returns reasonably good initial parameters for a VQE simulation. The construction of the object should set the state so that this function can produce its output. """ pass