How can we know the expected value of data errors in Stim?

[quantumadmin]

Stim is a software package developed by Google for simulating stabilizer circuits and error detection in quantum computing. It allows you to simulate the behavior of a stabilizer circuit under various error models and compute properties such as logical Pauli errors, error syndromes, and expected values.

To estimate the expected value of data errors using Stim, you would typically follow these steps:

Define Your Stabilizer Circuit: Create your stabilizer circuit using Stim's circuit description language. This involves specifying the gates and measurements you want to simulate.

Define the Error Model: Choose an error model that represents the errors you want to simulate. Stim supports various error models, including depolarizing errors, correlated errors, and custom error models.

Run Simulations: Use Stim to run simulations of your stabilizer circuit under the chosen error model. This involves simulating multiple shots (runs) of the circuit to observe the outcomes.

Analyze Results: Analyze the simulation results to compute the expected value of data errors. This could involve calculating the logical Pauli errors or error syndromes for specific error channels or error models.

Here's a simplified example of how you might use Stim to estimate the expected value of data errors:

Code: Select all

import stim

# Define the stabilizer circuit
circuit = stim.Circuit()
circuit.append_operation("H 0")
circuit.append_operation("CNOT 0 1")
# ... add more gates and measurements ...

# Define the error model (e.g., depolarizing channel)
error_model = stim.PauliStringErrorModel.from_bit_flip(0.1)

# Run simulations
num_shots = 1000
results = stim.TableauSimulator().sample(circuit, num_shots, error_model)

# Compute the expected value of data errors
expected_data_errors = results.data.sum() / num_shots

print("Expected value of data errors:", expected_data_errors)

Please note that the above example is a simplified illustration. The actual process of using Stim to estimate the expected value of data errors might involve more detailed steps and analysis, depending on the complexity of your stabilizer circuit and the error model you're considering.

For more comprehensive guidance and detailed examples, you should refer to the Stim documentation and resources provided by Google. The Stim GitHub repository (https://github.com/quantumlib/stim) is a valuable resource for learning how to use Stim for various quantum error simulations.