Update and refresh cirq-* module README files (#6900)

* Update and refresh cirq-* module README files

This updates all the cirq-* module files to fix some broken image
links, spiff up the layout and formatting, and add some additional
links here and there.

* Remove unused hyperlink target definition

rstcheck complains about it.

* Clarify the access restrictions to the quantum computing service

* Update & refresh cirq-*/README files & convert to md

This updates all the cirq-* module files to fix some broken image links, spiff up the layout and formatting, and add some additional links here and there.

As before, these remain purposefully short and fairly minimal because these are add-only modules to the main `cirq` distribution.

* Update setup.py's for README.md & refreshed version warning

This matches the changes in the top-level `setup.py` file, to adapt
them to use README.md instead of README.rst.

* Revise intro paragraphs and do misc. fix-ups

This updates the text about module purpose and access, and
does miscellaneous fixes such as conforming to Google's
Markdown style guidance.

* Remove "Google QAI" logo

It turns out that particular logo is strictly for use only on the QAI
website. I want to find another, but right now that doesn't seem to be
the best use of time, so let's just use only the Cirq logo and leave
it for now.

* Fix incorrect links for access and getting started

Reported by @Pavol in review comment
#6900 (comment)

* Remove circled "i" symbol

Per request by @Pavol in comment #6900 (comment)

cirq-aqt/README.md

@@ -0,0 +1,71 @@
+<div align="center">
+<img width="190px" alt="Cirq logo"
+src="https://raw.githubusercontent.com/quantumlib/Cirq/refs/heads/main/docs/images/Cirq_logo_color.svg"
+><img width="60px" height="0" alt=""><img width="200px" alt="AQT logo"
+src="https://www.aqt.eu/wp-content/uploads/2024/01/Logo-AQT-Alpine-Quantum-Technologies-2.png">
+</div>
+
+# cirq-aqt
+
+This is the Cirq-AQT integration module. It provides an interface that allows
+[Cirq] quantum algorithms to run on quantum computers made by [Alpine Quantum
+Technologies GmbH](https://www.aqt.eu). (See the [Documentation](#documentation)
+section below for information about getting access to AQT devices.)
+
+[Cirq] is a Python package for writing, manipulating, and running [quantum
+circuits](https://en.wikipedia.org/wiki/Quantum_circuit) on quantum computers
+and simulators. Cirq provides useful abstractions for dealing with today’s
+[noisy intermediate-scale quantum](https://arxiv.org/abs/1801.00862) (NISQ)
+computers, where the details of quantum hardware are vital to achieving
+state-of-the-art results. For more information about Cirq, please visit the
+[Cirq documentation site].
+
+[Cirq]: https://github.com/quantumlib/cirq
+[Cirq documentation site]: https://quantumai.google/cirq
+
+## Installation
+
+This module is built on top of [Cirq]; installing this module will
+automatically install the `cirq-core` module and other dependencies. There are
+two installation options for the `cirq-aqt` module:
+
+*   To install the stable version of `cirq-aqt`, use
+
+    ```shell
+    pip install cirq-aqt
+    ```
+
+*   To install the latest pre-release version of `cirq-aqt`, use
+
+    ```shell
+    pip install cirq-aqt~=1.0.dev
+    ```
+
+    (The `~=` has a special meaning to `pip` of selecting the latest version
+    compatible with the `1.*` and `dev` in the name. Despite appearances,
+    this will not install an old version 1.0 release!)
+
+If you would like to install Cirq with all the optional modules, not just
+`cirq-aqt`, then instead of the above commands, use `pip install cirq` for the
+stable release or `pip install cirq~=1.0.dev` for the latest pre-release
+version.
+
+## Documentation
+
+To get started with using AQT quantum computers through Cirq, please refer to
+the following documentation:
+
+*   [Access and authentication](https://quantumai.google/cirq/aqt/access).
+*   [Getting started
+    guide](https://quantumai.google/cirq/tutorials/aqt/getting_started).
+
+To get started with using Cirq in general, please refer to the [Cirq
+documentation site].
+
+For more information about getting help, reporting bugs, and other matters
+related to Cirq and the Cirq-AQT integration module, please visit the [Cirq
+repository on GitHub](https://github.com/quantumlib/Cirq).
+
+## Disclaimer
+
+Cirq is not an official Google product. Copyright 2019 The Cirq Developers.

cirq-aqt/setup.py

@@ -27,7 +27,7 @@
 )
 
 # README file as long_description.
-long_description = io.open('README.rst', encoding='utf-8').read()
+long_description = io.open('README.md', encoding='utf-8').read()
 
 # If CIRQ_PRE_RELEASE_VERSION is set then we update the version to this value.
 # It is assumed that it ends with one of `.devN`, `.aN`, `.bN`, `.rcN` and hence
@@ -37,9 +37,13 @@
 if 'CIRQ_PRE_RELEASE_VERSION' in os.environ:
     __version__ = os.environ['CIRQ_PRE_RELEASE_VERSION']
     long_description = (
-        "**This is a development version of Cirq-AQT and may be "
-        "unstable.**\n\n**For the latest stable release of Cirq-AQT "
-        "see**\n`here <https://pypi.org/project/cirq-aqt>`__.\n\n" + long_description
+        "<div align='center' width='50%'>\n\n"
+        "| ⚠️ WARNING |\n"
+        "|:----------:|\n"
+        "| **This is a development version of `cirq-aqt` and may be<br>"
+        "unstable. For the latest stable release of `cirq-aqt`,<br>"
+        "please visit** <https://pypi.org/project/cirq-aqt>.|\n"
+        "\n</div>\n\n" + long_description
     )
 
 # Read in requirements

cirq-core/README.md

@@ -0,0 +1,64 @@
+<div align="center">
+<img width="220px" alt="Cirq logo"
+src="https://raw.githubusercontent.com/quantumlib/Cirq/refs/heads/main/docs/images/Cirq_logo_color.svg">
+</div>
+
+# cirq-core
+
+[Cirq] is a Python package for writing, manipulating, and running [quantum
+circuits](https://en.wikipedia.org/wiki/Quantum_circuit) on quantum computers
+and simulators. Cirq provides useful abstractions for dealing with today’s
+[noisy intermediate-scale quantum](https://arxiv.org/abs/1801.00862) (NISQ)
+computers, where the details of quantum hardware are vital to achieving
+state-of-the-art results. For more information about Cirq, please visit the
+[Cirq documentation site].
+
+This Python module is `cirq-core`, which contains all the code you need to
+write quantum algorithms for NISQ devices and run them on the built-in Cirq
+simulators.
+
+To run algorithms on a given quantum computing platform, you will also need to
+install an appropriate Cirq hardware interface module. Please visit the
+[hardware section of the Cirq documentation
+site](https://quantumai.google/cirq/hardware) for information about the
+hardware interface modules currently available.
+
+[Cirq]: https://github.com/quantumlib/cirq
+[Cirq documentation site]: https://quantumai.google/cirq
+
+## Installation
+
+There are two installation options for the `cirq-core` module:
+
+*   To install the stable version of `cirq-core`, use
+
+    ```shell
+    pip install cirq-core
+    ```
+
+*   To install the latest pre-release version of `cirq-core`, use
+
+    ```shell
+    pip install cirq-core~=1.0.dev
+    ```
+
+    (The `~=` has a special meaning to `pip` of selecting the latest version
+    compatible with the `1.*` and `dev` in the name. Despite appearances,
+    this will not install an old version 1.0 release!)
+
+If you would like to install Cirq with all the optional modules, not just
+`cirq-core`, then instead of the above commands, use `pip install cirq` for the
+stable release or `pip install cirq~=1.0.dev` for the latest pre-release
+version.
+
+## Documentation
+
+To get started with using Cirq, please refer to the [Cirq documentation site].
+
+For more information about getting help, reporting bugs, and other matters
+related to Cirq and the Cirq-Core integration module, please visit the [Cirq
+repository on GitHub](https://github.com/quantumlib/Cirq).
+
+## Disclaimer
+
+Cirq is not an official Google product. Copyright 2019 The Cirq Developers.

cirq-core/setup.py

@@ -28,7 +28,7 @@
 )
 
 # README file as long_description.
-long_description = io.open('README.rst', encoding='utf-8').read()
+long_description = io.open('README.md', encoding='utf-8').read()
 
 # If CIRQ_PRE_RELEASE_VERSION is set then we update the version to this value.
 # It is assumed that it ends with one of `.devN`, `.aN`, `.bN`, `.rcN` and hence
@@ -38,9 +38,13 @@
 if 'CIRQ_PRE_RELEASE_VERSION' in os.environ:
     __version__ = os.environ['CIRQ_PRE_RELEASE_VERSION']
     long_description = (
-        "**This is a development version of Cirq-core and may be "
-        "unstable.**\n\n**For the latest stable release of Cirq-core "
-        "see**\n`here <https://pypi.org/project/cirq-core>`__.\n\n" + long_description
+        "<div align='center' width='50%'>\n\n"
+        "| ⚠️ WARNING |\n"
+        "|:----------:|\n"
+        "| **This is a development version of `cirq-core` and may be<br>"
+        "unstable. For the latest stable release of `cirq-core`,<br>"
+        "please visit** <https://pypi.org/project/cirq-core>.|\n"
+        "\n</div>\n\n" + long_description
     )
 
 # Read in requirements

cirq-google/README.md

@@ -0,0 +1,74 @@
+<div align="center">
+<img width="220px" alt="Cirq logo"
+src="https://raw.githubusercontent.com/quantumlib/Cirq/refs/heads/main/docs/images/Cirq_logo_color.svg">
+</div>
+
+# cirq-google
+
+This is the Cirq-Google integration module. It provides an interface to
+Google's [Quantum Computing
+Service](https://quantumai.google/cirq/google/concepts), and also contains
+additional tools for calibration and characterization of Google's quantum
+hardware devices.
+
+| Please note!         |
+|:--------------------:|
+| Google's quantum hardware is currently available only to authorized partners. Access requires an application, usually with a Google sponsor.|
+
+[Cirq] is a Python package for writing, manipulating, and running [quantum
+circuits](https://en.wikipedia.org/wiki/Quantum_circuit) on quantum computers
+and simulators. Cirq provides useful abstractions for dealing with today’s
+[noisy intermediate-scale quantum](https://arxiv.org/abs/1801.00862) (NISQ)
+computers, where the details of quantum hardware are vital to achieving
+state-of-the-art results. For more information about Cirq, please visit the
+[Cirq documentation site].
+
+[Cirq]: https://github.com/quantumlib/cirq
+[Cirq documentation site]: https://quantumai.google/cirq
+
+## Installation
+
+This module is built on top of [Cirq]; installing this module will
+automatically install `cirq-core` and other dependencies. There are two
+installation options for the `cirq-google` module:
+
+*   To install the stable version of `cirq-google`, use
+
+    ```shell
+    pip install cirq-google
+    ```
+
+*   To install the latest pre-release version of `cirq-google`, use
+
+    ```shell
+    pip install cirq-google~=1.0.dev
+    ```
+
+    (The `~=` has a special meaning to `pip` of selecting the latest version
+    compatible with the `1.*` and `dev` in the name. Despite appearances,
+    this will not install an old version 1.0 release!)
+
+If you would like to install Cirq with all the optional modules, not just
+`cirq-google`, then instead of the above commands, use `pip install cirq` for
+the stable release or `pip install cirq~=1.0.dev` for the latest pre-release
+version.
+
+## Documentation
+
+To get started with using Google quantum computers through Cirq, please refer to
+the following documentation:
+
+*   [Access and authentication](https://quantumai.google/cirq/google/access).
+*   [Getting started
+    guide](https://quantumai.google/cirq/tutorials/google/start).
+
+To get started with using Cirq in general, please refer to the [Cirq
+documentation site].
+
+For more information about getting help, reporting bugs, and other matters
+related to Cirq and the Cirq-Core integration module, please visit the [Cirq
+repository on GitHub](https://github.com/quantumlib/Cirq).
+
+## Disclaimer
+
+Cirq is not an official Google product. Copyright 2019 The Cirq Developers.

cirq-google/setup.py

@@ -26,7 +26,7 @@
 )
 
 # README file as long_description.
-long_description = open('README.rst', encoding='utf-8').read()
+long_description = open('README.md', encoding='utf-8').read()
 
 # If CIRQ_PRE_RELEASE_VERSION is set then we update the version to this value.
 # It is assumed that it ends with one of `.devN`, `.aN`, `.bN`, `.rcN` and hence
@@ -36,9 +36,13 @@
 if 'CIRQ_PRE_RELEASE_VERSION' in os.environ:
     __version__ = os.environ['CIRQ_PRE_RELEASE_VERSION']
     long_description = (
-        "**This is a development version of Cirq-google and may be "
-        "unstable.**\n\n**For the latest stable release of Cirq-google "
-        "see**\n`here <https://pypi.org/project/cirq-google>`__.\n\n" + long_description
+        "<div align='center' width='50%'>\n\n"
+        "| ⚠️ WARNING |\n"
+        "|:----------:|\n"
+        "| **This is a development version of `cirq-google` and may be<br>"
+        "unstable. For the latest stable release of `cirq-google`,<br>"
+        "please visit** <https://pypi.org/project/cirq-google>.|\n"
+        "\n</div>\n\n" + long_description
     )
 
 # Read in requirements