orquestra-vqa is a library with core functionalities for implementing variational quantum algorithms developed by Zapata for our Orquestra platform.
orquestra-vqa provides:
- interfaces for implementing ansatzes including qaoa and qcbm.
- optimizers and cost functions tailored to vqa
- misc functions such as grouping, qaoa interpolation, and estimators
Even though it's intended to be used with Orquestra, orquestra-vqa can be also used as a Python module.
To install it you need to run pip install orquestra-vqa or pip install . from the main directory. This installation will install its dependencies: orquestra-quantum, orquestra-opt and orquestra-cirq.
Here's an example of how to use methods from orquestra-vqa to create a cost function for qcbm and optimize it using scipy optimizer.
from orquestra.vqa.cost_function.qcbm_cost_function import create_QCBM_cost_function
from orquestra.vqa.ansatz.qcbm import QCBMAnsatz
from orquestra.opt.history.recorder import recorder
from orquestra.quantum.symbolic_simulator import SymbolicSimulator
from orquestra.quantum.distributions import compute_mmd
from orquestra.quantum.distributions import MeasurementOutcomeDistribution
from orquestra.opt.optimizers.scipy_optimizer import ScipyOptimizer
import numpy as np
target_distribution = MeasurementOutcomeDistribution(
{
"0000": 1.0,
"0001": 0.0,
"0010": 0.0,
"0011": 1.0,
"0100": 0.0,
"0101": 1.0,
"0110": 0.0,
"0111": 0.0,
"1000": 0.0,
"1001": 0.0,
"1010": 1.0,
"1011": 0.0,
"1100": 1.0,
"1101": 0.0,
"1110": 0.0,
"1111": 1.0,
}
)
def orquestra_vqa_example_function():
ansatz = QCBMAnsatz(1, 4, "all")
backend = SymbolicSimulator()
distance_measure_kwargs = {
"distance_measure": compute_mmd,
"distance_measure_parameters": {"sigma": 1},
}
cost_function = create_QCBM_cost_function(
ansatz,
backend,
10,
**distance_measure_kwargs,
target_distribution=target_distribution
)
optimizer = ScipyOptimizer(method="L-BFGS-B")
initial_params = np.ones(ansatz.number_of_params) / 5
opt_results = optimizer.minimize(cost_function, initial_params)
return opt_results
orquestra_vqa_example_function()You can find the development guidelines in the orquestra-quantum repository.