Local Braket Qubit Executor

This quantum executor accesses the local Braket quantum circuit simulator ("braket.local.qubit").

It utilizes the Pennylane plugin found here. LocalBraketQubitExecutor introduces thread-based parallelism for circuit execution on the "braket.local.qubit" device.

1. Installation

LocalBraketQubitExecutor is not included in base Covalent. To use it, you will need to install the Covalent with:

pip install covalent[braket]

2. Usage Example

Using LocalBraketQubitExecutor is simple:

# Local simulator
executor = ct.executor.LocalBraketQubitExecutor(
    device="default",
    shots=1024,
    num_threads=2
)

@ct.qelectron(executors=executor)
@qml.qnode(qml.device("default.qubit", wires=2, shots=1024))
def circuit(x):
    qml.IQPEmbedding(features=x, wires=[0, 1])
    qml.Hadamard(wires=1)
    return [qml.expval(qml.PauliZ(0)), qml.expval(qml.PauliZ(1))]

As a QElectron, the circuit can be called either normally or asynchronously using circuit.run_later().

Synchronous example output is below

>>> print(circuit([0.5, 0.1]))

[array(0.008), array(0.996)]

and asynchronously:

>>> x = [0.6, -1.57]

>>> # Queue jobs for all three circuit calls simultaneously on.
>>> futs = [circuit.run_later(x) for _ in range(3)]

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

[[array(-0.02), array(0.01)],
 [array(0.014), array(-0.022)],
 [array(-0.074), array(0.05)]]

3. Overview of Configuration

The LocalBraketQubitExecutor configuration is found under [qelectron.LocalBraketQubitExecutor] in the Covalent configuration file.

Config Key	Is Required	Default	Description
backend	No	“default”	The type of simulator backend to be used. Choices are "default", "braket_sv", "braket_dm" and "braket_ahs".

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