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How to install QDK for error correction

Install the qdk.ec Python module from the Microsoft Quantum Development Kit (QDK) to develop and test quantum error correction (QEC) codes and protocols. The module uses the qodec package for protocol models and persistence.

Prerequisites

Install these tools before you start:

  • Python 3.11 or later
  • pip or another Python package manager

The base qdk package supports Python 3.10 or later. The qdk.ec module requires Python 3.11 or later because of its qodec dependency.

(Optional) Create a virtual environment

Use a virtual environment to keep the qdk.ec dependencies separate from other Python projects.

  1. Create the virtual environment, for example .venv.

    python -m venv .venv

  2. Activate the environment.

    On Windows:

    .venv\Scripts\Activate.ps1

    On Linux or macOS:

    source .venv/bin/activate

  3. Update pip in the active environment.

    python -m pip install --upgrade pip

Install QDK for error correction

Install the qdk Python package with the ec extra.

python -m pip install --upgrade "qdk[ec]"

To use Jupyter Notebook and QDK widgets, install the jupyter extra too.

python -m pip install --upgrade "qdk[ec,jupyter]" ipykernel

The ec extra installs qodec, the Stim parser on supported platforms, and the algebra and solver packages that qdk.ec uses. It also includes HiGHS for distance searches.

Note

The qdk.ec module uses the separate Stim Python package through qodec. It doesn't use the qdk.stim module.

Install on Linux Arm64 or Windows Arm64

Stim doesn't publish wheels for Linux Arm64 or Windows Arm64. On those platforms, qdk[ec] installs qodec without its Stim parser.

You can load and save YAML qodecs and use a custom circuit parser. Features that parse format="stim" circuits don't work on these platforms. This limitation includes qdk.ec.build_qodec.

To enable the parser, install Stim separately. Your system needs a C++20 compiler to install Stim.

python -m pip install --upgrade stim

Install optional distance and decoder packages

The default distance solver uses HiGHS, which the qdk.ec module includes. To select the optional MWPF solver, install mwpf separately.

python -m pip install mwpf

To use the deq circuit-level decoder with qdk.simulation.run_qir, install deq and deq-runtime.

python -m pip install deq deq-runtime

The QDK tests the deq adapter with version 0.5.7 of deq and deq-runtime.

Note

The deq-runtime package doesn't publish Windows Arm64 wheels. The deq adapter also requires Stim, which doesn't publish Linux Arm64 or Windows Arm64 wheels.

Verify the installation

Create a Python file or Jupyter Notebook cell with the following code. The example defines the four-qubit C4 code and checks its distance.

import qodec
from qdk import ec

c4 = qodec.Code(
    "C4",
    stabilizers=["X_0 X_1 X_2 X_3", "Z_0 Z_1 Z_2 Z_3"],
    x=["X_0 X_1", "X_0 X_2"],
    z=["Z_0 Z_2", "Z_0 Z_1"],
)

distance = ec.CodeProfile(c4).distance()
print("Code distance:", distance)
assert distance.value == 2

The program prints this result:

Code distance: 2

If the import and distance search succeed, the core qdk.ec dependencies are ready.

Verify Stim support

Run this check on a platform that supports the Stim parser.

from qdk import ec

protocol = ec.build_qodec(c4, strategy="bare-css/v1", strict=False)
print(ec.audit(protocol))

A correctly generated protocol prints an audit summary. A protocol that passes all checks prints:

audit: ok

If build_qodec reports that no parser exists for the stim format, confirm that you installed qdk[ec] in the active environment. On Linux Arm64 or Windows Arm64, install Stim from source and restart Python or the Jupyter kernel.

Continue with protocol development

To define a code, build a qodec, and validate its gadgets, see Develop and validate a QEC protocol.

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