Testing a quantum task with the local simulator

You can send quantum tasks directly to a local simulator for rapid prototyping and testing. This simulator runs in your local environment, so you do not need to specify an Amazon S3 location. The results are computed directly in your session. To run a quantum task on the local simulator, you must only specify the shots parameter.

The following commands are all identical and instantiate the state vector (noise free) local simulator.

# import the LocalSimulator module
from braket.devices import LocalSimulator
# the following are identical commands
device = LocalSimulator()
device = LocalSimulator("default")
device = LocalSimulator(backend="default")
device = LocalSimulator(backend="braket_sv")

Then run a quantum task with the following.

my_task = device.run(circ, shots=1000)

To instantiate the local density matrix (noise) simulator customers change the backend as follows.

# import the LocalSimulator module
from braket.devices import LocalSimulator
device = LocalSimulator(backend="braket_dm")

Measuring specific qubits on the local simulator

The local state vector simulator and local density matrix simulator support running circuits where a subset of the circuit's qubits can be measured, which is often called partial measurement.

For example, in the following code you can create a two-qubit circuit and only measure the first qubit by adding a measure instruction with the target qubits to the end of the circuit.

# Import the LocalSimulator module
from braket.devices import LocalSimulator 

# Use the local simulator device
device = LocalSimulator()

# Define a bell circuit and only measure 
circuit = Circuit().h(0).cnot(0, 1).measure(0)

# Run the circuit
task = device.run(circuit, shots=10)

# Get the results
result = task.result()

# Print the measurement counts for qubit 0
print(result.measurement_counts)