This client uses the cirq interface to submit quantum circuits to the Floq Service. This client is designed to be simple to use for those familiar with the cirq.Simulator interface.

python3 -m virtualenv venv --python=python3.8  # At least Python 3.7
source venv/bin/activate
pip install floq_client

Full documentation is available at https://floq-client.readthedocs.io/

Currently the Floq client supports cirq's SimulatesSamples and the SimulatesExpectationValues simulators. These interfaces include methods for running sampling and calculating expectation values of single circuits, batches of circuits or circuits to be resolved with parameter value sweeps.

Check out the samples in the samples directory.

import floq.client

qubits = cirq.LineQubit.range(26)
param_resolver = cirq.ParamResolver({'a': 1})
a = sympy.Symbol('a')
circuit = cirq.Circuit(
    [cirq.X(q) ** a for q in qubits] +
    [cirq.measure(q) for q in qubits])

client = floq.client.CirqClient("my_api_key")
result = client.simulator.run(circuit, param_resolver) # Results from the cloud hurray!

See SimulatesSamples interface documentation for more information.

Note: This client does not support the async run calls currently.

See SimulatesExpectationValues interface documentation for more information.

The client also provides calculation of expectation values against cirq.PauliSum observables:

import floq.client

client = floq.client.CirqClient("my_api_key")

# Find expectation against a single Paulisum
magnetization_op = sum([cirq.Z(q) for q in qubits])
client.simulator.simulate_expectation_values(
    circuit,
    magnetization_op,
    param_resolvers)

    # returns [exp_value]

# Or against multiple
client.simulator.simulate_expectation_values(
    circuit,
    [magnetization_op, cirq.X(qubits[0]) + cirq.Y(qubits[0])]
)
    # returns [exp1, exp2] - one expectation per observable

# Also run sweeps over param_resolver values
client.simulator.simulate_expectation_values_sweep(
    circuit,
    [observable1, observable2],
    cirq.Sweepable
)
    # returns [[exp1, exp2], ...] - one list of expectations per param set

Note: The SimulatesExpectationValues interface is available in cirq>=0.10.0.

Floq client also provides an interface for inspecting and flushing pending jobs queue. Each time a quantum circuit is submitted to the cloud, the Floq service replies with unique job id and the job is queued for the execution.

The example code is located in jobs_queue.py sample file.

Each individual API key is bound to dedicated TPU worker running in the cloud. The Floq Client provides an interace for starting, stopping or restarting the worker (in case it enters into some unexpected state). Additionally, you can always check current worker status.

The example code is located in worker_manager.py sample file.

Both jobs queue and TPU worker can be controlled manually using provided CLI script. Simply provide Floq API key as the input argument and the resource command as shown below:

# Jobs queue commands
floq-client API_KEY jobs {display,flush}

# TPU worker commands
floq-client API_KEY worker {restart,start,stop,status}

To use Floq-backend in PennyLane, please install the latest version of PennyLane-Cirq plugin. The sample code is located in the pennylane.py file.

Keep in mind that you are on the frontier and this is a very experimental service! There will be trials, tribulations, and bugs!

Please let us know about issues you encounter and mail us at [email protected].

That being said there are a few known limitations at this point. In order to be conservative we have implemented restrictions on the size of circuits, number of observables, etc... We are working hard to push this forward, bear with us.

Enjoy!