Tweak layout, shorten intro, add citation, add QAI logo (#8)

* Tweak layout, shorten intro, add QAI logo

Changes:

- Edited the lead-in paragraph in an attempt to reduce redundancy with
  the "Features" section

- Added a TOC and some customizations to the layout of the top

- Added the QAI logo at the bottom of the page

* Add QAI logo file

* Add citation & help sections

Author: mhucka

README.md

@@ -1,32 +1,39 @@
+<div align="center">
+
 # Tesseract Decoder
 
-A Search-Based Decoder for Quantum Error Correction
+A Search-Based Decoder for Quantum Error Correction.
 
 [![Licensed under the Apache 2.0 open-source license](https://img.shields.io/badge/License-Apache%202.0-3c60b1.svg?logo=opensourceinitiative\&logoColor=white\&style=flat-square)](https://github.com/quantumlib/tesseract-decoder/blob/main/LICENSE)
+![C++](https://img.shields.io/badge/C++-20-fcbc2c?style=flat-square&logo=C%2B%2B&logoColor=white)
+
+[Installation](#installation) &ndash;
+[Usage](#usage) &ndash;
+[Help](#help) &ndash;
+[Citation](#citation) &ndash;
+[Contact](#contact)
 
-## Overview
+</div>
 
 Tesseract is a Most Likely Error decoder designed for Low Density Parity Check (LDPC) quantum
-error-correcting codes. It employs the A\* search algorithm to efficiently navigate the
-exponentially large graph of possible error subsets, identifying the most likely error configuration
-consistent with the observed syndrome. Tesseract leverages several pruning heuristics and manifold
-orientation techniques to achieve significant speed improvements over traditional integer
-programming-based decoders, while maintaining comparable accuracy at moderate physical error rates.
+error-correcting codes. It applies pruning heuristics and manifold orientation techniques during a
+search over the error subsets to identify the most likely error configuration consistent with the
+observed syndrome. Tesseract archives significant speed improvements over traditional integer
+programming-based decoders while maintaining comparable accuracy at moderate physical error rates.
 
 We tested the Tesseract decoder for:
 
 *   Surface codes
 *   Color codes
 *   Bivariate-bicycle codes
-*   Transversal CNOT protocols for surface codes Stim circuits for these protocols are stored in
-    `testdata/`.
+*   Transversal CNOT protocols for surface codes
 
 ## Features
 
 *   **A\* search:** deploys [A\* search](https://en.wikipedia.org/wiki/A*_search_algorithm) while
     running a [Dijkstra algorithm](https://en.wikipedia.org/wiki/Dijkstra%27s_algorithm) with early
     stop for high performance.
-*  **Stim and DEM Support:** processes [Stim](https://github.com/quantumlib/stim) circuit files and
+*   **Stim and DEM Support:** processes [Stim](https://github.com/quantumlib/stim) circuit files and
     [Detector Error Model
     (DEM)](https://github.com/quantumlib/Stim/blob/main/doc/file_format_dem_detector_error_model.md)
     files with arbitrary error models.
@@ -112,7 +119,6 @@ Using a Detection Event File and Observable Flips:
 Tesseract supports reading and writing from all of Stim's standard [output
 formats](https://github.com/quantumlib/Stim/blob/main/doc/result_formats.md).
 
-
 ### Performance Optimization
 
 Here are some tips for improving performance:
@@ -132,7 +138,36 @@ Here are some tips for improving performance:
 *   *DEM usage frequency output*: if `--dem-out` is specified, outputs estimated error frequencies.
 *   *Statistics output*: includes number of shots, errors, low confidence shots, and processing time.
 
-<!-- ## Citing Tesseract Decoder<a name="how-to-cite-tesseract"> -->
+## Help
+
+*   Do you have a feature request or want to report a bug? [Open an issue on
+    GitHub] to report it!
+*   Do you have a code contribution? Read our [contribution guidelines], then
+    open a [pull request]!
+
+[Open an issue on GitHub]: https://github.com/quantumlib/tesseract-decoder/issues/new/choose
+[contribution guidelines]: https://github.com/quantumlib/tesseract-decoder/blob/main/CONTRIBUTING.md
+[pull request]: https://help.github.com/articles/about-pull-requests
+
+We are committed to providing a friendly, safe, and welcoming environment for
+all. Please read and respect our [Code of Conduct](CODE_OF_CONDUCT.md).
+
+## Citation
+
+When publishing articles or otherwise writing about Tesseract Decoder, please
+cite the following:
+
+```latex
+@misc{beni2025tesseractdecoder,
+    title={Tesseract: A Search-Based Decoder for Quantum Error Correction},
+    author={Laleh Aghababaie Beni and Oscar Higgott and Noah Shutty},
+    year={2025},
+    eprint={2503.10988},
+    archivePrefix={arXiv},
+    primaryClass={quant-ph},
+    url={https://arxiv.org/abs/2503.10988},
+}
+```
 
 ## Contact
 
@@ -142,6 +177,13 @@ For any questions or concerns not addressed here, please email <quantum-oss-main
 
 Tesseract Decoder is not an officially supported Google product. This project is not eligible for
 the [Google Open Source Software Vulnerability Rewards
-Program](https://bughunters.google.com/open-source-security). 
+Program](https://bughunters.google.com/open-source-security).
 
 Copyright 2025 Google LLC.
+
+<div align="center">
+  <a href="https://quantumai.google">
+    <img width="15%" alt="Google Quantum AI"
+         src="./docs/images/quantum-ai-vertical.svg">
+  </a>
+</div>