single_shot_3D_HGP

C++ implementation of a single-shot decoder for three-dimensional homological product codes, using belief propagation with ordered statistics post-processing^1,2. The accompanying paper is available on the arXiv³.

[1]: Pavel Panteleev and Gleb Kalachev, "Degenerate Quantum LDPC Codes With Good Finite Length Performance", arXiv:1904.02703
[2]: Joschka Roffe, David R. White, Simon Burton and Earl T. Campbell, "Decoding Across the Quantum LDPC Code Landscape", arXiv:2005.07016
[3]: Armanda O. Quintavalle, Michael Vasmer, Joschka Roffe and Earl T. Campbell, "Single-shot error correction of three-dimensional homological product codes", arXiv:2009.11790

Setup

Clone the repo and import submodules

git clone https://github.com/MikeVasmer/single_shot_3D_HGP.git
cd single_shot_3D_HGP
git submodule update --init --recursive

Build the demo sim script

The demo sim script can be found at "sim_scripts/single_shot_hgp3d.cpp". To build it, run the following commands from the repository route

mkdir build
cd build
cmake ../
make
cd ..

Demo scripts

Demo input files for the 3D surface and toric codes can be found in the "sim_scripts" directory. Run them with the following commands:

3D surface code

build/single_shot_hgp3d sim_scripts/surface3D_input_demo.json sim_scripts/output

3D Toric code

build/single_shot_hgp3d sim_scripts/toric3D_input_demo.json sim_scripts/output

General sim script syntax

The general syntax for running the sim script is as follows

build/single_shot_hgp3d <path_to_input_file.json> <path_to_output_directory>

Input file structure

The single_shot_hgp3d.cpp script takes JSON files as input. An example input file is shown below:

{
{
  "exec_file": "sim_scripts/single_shot_hgp3d.cpp",
  "target_runs": 500,
  "code_type": "toric3D",
  "distance_label": 5,
  "code_label": "toric3D_5",
  "hx_filename": "codes/toric3D/toric3D_5_hx.alist",
  "lx_filename": "codes/toric3D/toric3D_5_lx.alist",
  "mx_filename": "codes/toric3D/toric3D_5_mx.alist",
  "lmx_filename": "codes/toric3D/toric3D_5_lmx.alist",
  "mxlmx_filename": "codes/toric3D/toric3D_5_mxlmx.alist",
  "sustained_threshold_depth": 4,
  "input_seed": 6363,
  "bp_method": "product_sum",
  "bp_max_iter": 50,
  "osd_method": "combination_sweep",
  "osd_order": 50,
  "failure_mode_subroutine": true,
  "bit_error_rate": 0.026,
  "syndrome_error_rate": 0.026
}
}

Where

• "exec_file": the location of the sim script that is being run (for future reference)
• "target_runs": the total number of runs to simulate
• "sustained_threshold_depth": the number of rounds of noisy error correction to be run per run
• "code_type": whatever you like
• "distance_label": eg. lattice size or the code distance
• "code_label": whatever you like
• "hx_filename": alist file for the hx matrix
• "lx_filename": alist file for the lx matrix
• "mx_filename": alist file for the mx matrix
• "lmx_filename": alist file for the lmx matrix
• "mxlmx_filename": alist file for the mxlmx matrix
• "input_seed": an integer,
• "bp_method": the type of BP. Current options are: 1) "product_sum"; 2) "min_sum"; 3) "min_sum_min_synd"
• "bp_max_iter": the maximum number of iterations for BP
• "osd_method": Currenlty three options are available: 1) "combination_sweep"; 2) "exhaustive"; 3) "osd_0". The details of these techniques are described in arXiv:2005.07016.
• "osd_order": integer
• "failure_mode_subroutine": true/false
• "bit_error_rate": error rate on qubits
• "syndrome_error_rate": error rate on syndromes

Software

This library makes use of the following software:

• BP+OSD - Belief propagation plus ordered statistics decoding for quantum LDPC codes, Joschka Roffe
• Sofware for low density parity check codes, Radford M. Neal
• JSON for modern C++, Niels Lohmann
• The Mtwister C library, Evan Sultanik

Licence

MIT License

Copyright (c) 2020 Michael Vasmer & Joschka Roffe

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.