Code repository for "Relaxing Hardware Requirements for Surface Code Circuits using Time-dynamics"

This repository contains the code used to generate circuits, and collect sample statistics, used in the paper "Relaxing Hardware Requirements for Surface Code Circuits using Time-dynamics".

reproducing figures and statistics

Sitting next to this README, at the root of the repository, are several scripts: step1_generate_circuits.sh, step2_collect_stats.sh step3_derive_fused_stats.sh and step4_plots.sh. Most plots from the paper can be reproduced by setting up a python environment and then running these scripts in order. One major difference is that the collection script has been changed to use pymatching as the decoder, instead of a proprietary internal decoder that performs correlated decoding. The logical error rates of this decoder as slightly better than pymatching. Also, the collection script has been configured to take a million shots instead of a hundred million, so that it finishes faster. Interested users can increase this number.

Assuming a linux-like system with a working python installation, and a bit of luck, the following script should in principle reproduce the results from the paper after running for a few days:

# Preparation: make virtual environment
python -m venv .venv
source .venv/bin/activate
# Preparation: install dependencies
sudo apt install parallel  # scripts use gnu-parallel to distribute circuit generatoin and plotting work.
pip install -r requirements.txt

./step1_generate_circuits.sh
./step2_collect_stats  # This one might take a week!
# Maybe edit step2 to take fewer shots, or edit step1 to make fewer circuits?

./step3_derive_fused_stats.sh
./step4_plot_stats

directory structure

• .: top level of repository, with this README and the step# scripts
• ./tools: scripts used by the top-level step# scripts to perform tasks such as generating specific circuits and plots
• ./src: source root of the code; the directory to include in PYTHONPATH
• ./src/midout the python package containing the circuit generation and debugging code (the name is a Silicon Valley reference, due to many of the circuits being built by conceptually starting from the mid cycle state)
• ./src/midout/planar: location of code producing surface code circuits on a bounded grid
• ./src/midout/toric: location of code producing surface code circuits on a periodic grid
• ./src/midout/walking: location of code producing walking surface code circuits
• ./src/midout/gen, ./src/midout/util: utility code for generating and debugging circuits
• ./out: Scripts are configured to create this directory and write their output to various locations within it.

Unfortunately, there isn't really a consistent "style" to the circuit generation code. Every circuit is done a bit differently, because we were actively learning and experimenting with different techniques for making them. This makes the code a bit of a cacophony of concepts, some of which definitely worked better than others.