QECC: An MQT tool for Quantum Error Correcting Codes written in C++

:warning: This project is still in early development and breaking changes might happen frequently.

(Additionally to the basic numerical results already provided, further data will be published continually)

A tool for quantum error correcting codes and numerical simulations developed by the Chair for Design Automation at the Technical University of Munich based on methods proposed in [1]. QECC is part of the Munich Quantum Toolkit (MQT).

The tool can be used to:

• Decode quantum LDPC codes and conduct respective numerical simulations.
  • At the moment the general QLDPC decoder [2] and a heuristic (which improves the runtime of the algorithm) [1] are implemented. Currently, open-source software by Joschka Roffe et al.: [3] is used to construct codes (toric, lifted product and hypergraph product).
• Apply error correction to quantum circuits.
  • The framework allows to apply different ECC schemes to quantum circuits and either exports the resulting circuits or simulates them using Qiskit [4]. Currently, 6 different ECCs are supported with varying extend of functionality.

If you have any questions, feel free to contact us via quantum.cda@xcit.tum.de or by creating an issue on GitHub.

Getting Started

QECC is available via PyPI for Linux, macOS, and Windows.

(venv) $ pip install mqt.qecc

The following code gives an example on the usage:

Example for decoding quantum LDPC codes

from mqt.qecc import *
import numpy as np

H = [
    [1, 0, 0, 1, 0, 1, 1],
    [0, 1, 0, 1, 1, 0, 1],
    [0, 0, 1, 0, 1, 1, 1]
]
code = Code(H, H)
decoder = UFHeuristic()
decoder.set_code(code)
x_err = sample_iid_pauli_err(code.N, 0.05)
decoder.decode(code.get_x_syndrome(x_err))
result = decoder.result
print(result)
residual_err = np.array(x_err) ^ np.array(result.estimate)
print(code.is_x_stabilizer(residual_err))

Example for applying error correction to a circuit

from mqt import qecc

file = "path/to/qasm/file.qasm"  # Path to the OpenQASM file the quantum circuit shall be loaded from
ecc = "Q7Steane"  # Error correction code that shall be applied to the quantum circuit
ecc_frequency = 100  # After how many times a qubit is used, error correction is applied

result = qecc.apply_ecc(file, ecc, ecc_frequency)

# print the resulting circuit as OpenQASM string
print(result["circ"])

A wrapper script for applying error correction to quantum circuits (provided as OpenQASM) and performing a noise-aware quantum circuit simulation (using Qiskit) is provided. The script can be used like this:

$ (venv) ecc_qiskit_wrapper -ecc Q7Steane -fq 100 -m D -p 0.0001 -n 2000 -fs aer_simulator_stabilizer -s 0 -f  ent_simple1000_n2.qasm
_____Trying to simulate with D (prob=0.0001, shots=2000, n_qubits=17, error correction=Q7Steane) Error______
State |00> probability 0.515
State |01> probability 0.0055
State |10> probability 0.0025
State |11> probability 0.477

Detailed documentation on all available methods, options, and input formats is available at ReadTheDocs.

System Requirements and Building

The implementation is compatible with any C++17 compiler and a minimum CMake version of 3.19. Please refer to the documentation on how to build the project.

Building (and running) is continuously tested under Linux, macOS, and Windows using the latest available system versions for GitHub Actions.

Reference

If you use our tool for your research, we will be thankful if you refer to it by citing the appropriate publication:

T. Grurl, C. Pichler, J. Fuss and R. Wille, "Automatic Implementation and Evaluation of Error-Correcting Codes for Quantum Computing: An Open-Source Framework for Quantum Error-Correction," in International Conference on VLSI Design and International Conference on Embedded Systems (VLSID), 2023

L. Berent, L. Burgholzer, and R. Wille, "Software Tools for Decoding Quantum Low-Density Parity Check Codes," in Asia and South Pacific Design Automation Conference (ASP-DAC), 2023