Simulator

This quantum executor introduces thread- or process-based parallelism to Pennylane circuits that utilize simulation-based devices (like "default.qubit" or "lightning.qubit").

1. Installation

No additional installation is required.

2. Usage Example

A thread-based Simulator is the default quantum executor for QElectrons.

import covalent as ct
import pennylane as qml

@ct.qelectron
@qml.qnode(qml.device("lightning.qubit", wires=2), interface="torch")
def circuit(x):
    qml.IQPEmbedding(features=x, wires=[0, 1])
    qml.Hadamard(wires=1)
    return qml.probs(wires=range(2))

Once converted to a QElectron, the circuit can be called either normally or asynchronously via circuit.run_later().

A synchronous example is show below.

>>> circuit([1.3, -0.7]), circuit([1.3, -0.7])

(tensor([0.3169, 0.3169, 0.1831, 0.1831], dtype=torch.float64),
 tensor([0.3169, 0.3169, 0.1831, 0.1831], dtype=torch.float64))

Alternatively, doing this asynchronously:

>>> # Use separate threads to run two circuits simultaneously.
>>> futs = [circuit.run_later([1.3, -0.7]) for _ in range(2)]

# Wait for all circuits to finish.
>>> [fut.result() for fut in futs]

[tensor([0.3169, 0.3169, 0.1831, 0.1831], dtype=torch.float64),
 tensor([0.3169, 0.3169, 0.1831, 0.1831], dtype=torch.float64)]

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