Simulation of STIM-like circuits

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Deltakit provides both client-side and server-side simulation capabilities. For typical simulations involving only features provided by STIM, simulation can be performed locally; this has the advantage of avoiding data transfer and network latency for small circuits. If the simulation involves advanced features, such as leakage support, simulations will be performed on a Deltakit server.

Simple simulation example

In this example we run a circuit to prepare Bell’s state. Measurements are random, but they should be perfectly correlated.

from deltakit.explorer.simulation import simulate_with_stim

bell_circuit = """
R 0 1
H 0
CX 0 1
M 0 1
"""

By default, simulations run locally.

measurements, _ = simulate_with_stim(bell_circuit, shots=8)
measurements

Measurements(data=RAMData(data_format=<DataFormat.B8: 'b8'>, content=array([[0, 0],
       [1, 1],
       [0, 0],
       [1, 1],
       [0, 0],
       [1, 1],
       [1, 1],
       [0, 0]], dtype=uint8), data_width=-1))

When a Client instance is provided using the client parameter, simulations are run on the cloud.

from deltakit.explorer import Client
Client.set_token('<your token here>')  # see "Setup" documentation
client = Client.get_instance()
measurements, _ = simulate_with_stim(bell_circuit, shots=8, client=client)
measurements

Measurements(data=RAMData(data_format=<DataFormat.B8: 'b8'>, content=array([[0, 0],
       [0, 0],
       [0, 0],
       [1, 1],
       [0, 0],
       [1, 1],
       [0, 0],
       [1, 1]], dtype=uint8), data_width=2))

Leakage simulation

Server-side simulator supports additional (not included in STIM) instructions that enable simulation of leakage. LEAKAGE(probability) [list of targets] defines a probabilistic leakage event. This line will generate leakage event of 1% probability on qubits 0, 1 and 2.

LEAKAGE(0.01) 0 1 2

The HERALD_LEAKAGE_EVENT [list of target] operator works very similar to a measurement instruction and records bits of information about the leakage state of the qubits. They should always accompain measurement instructions. This is how instructions work together:

R 0 1

LEAKAGE(1.0) 1          # leakage with 100% probability
M 0                     # measurement value for qubit 0
HERALD_LEAKAGE_EVENT 0  # leakage state for qubit 0, will be 0
M 1                     # measurement value for qubit 1, unpredictable
HERALD_LEAKAGE_EVENT 1  # leakage state for qubit 1, will be 1

The code below runs an example with probabilistic leakage. The client argument must be provided when running simulations involving leakage.

leakage_bell_stim = """
R 0 1
LEAKAGE(0.5) 1   # qubit 1 leaks 50%% of the time
M 0 1
HERALD_LEAKAGE_EVENT 0 1
"""
measurements, leakage = simulate_with_stim(
    stim_circuit=leakage_bell_stim,
    shots=10,
    client=client,
)

measurements

Measurements(data=RAMData(data_format=<DataFormat.B8: 'b8'>, content=array([[0, 0],
       [0, 0],
       [0, 0],
       [0, 1],
       [0, 1],
       [0, 0],
       [0, 0],
       [0, 1],
       [0, 0],
       [0, 0]], dtype=uint8), data_width=2))

leakage

LeakageFlags(data=RAMData(data_format=<DataFormat.B8: 'b8'>, content=array([[0, 0],
       [0, 1],
       [0, 1],
       [0, 1],
       [0, 1],
       [0, 1],
       [0, 0],
       [0, 1],
       [0, 0],
       [0, 0]], dtype=uint8), data_width=2))