Update and make minor additions to docs/ in time for Cirq 1.5 (#7175)

* Add citation for Tesseract Decoder

* Add Tesseract Decoder & remove Rigetti

* Remove statement about cirq-rigetti

It seems like the Docker container may not be used solely for the
Rigetti module, so I left the other text about Docker and only removed
the statement involving Rigetti.

* Add mention of Tesseract & fix a couple of tiny niggles

* Remove mention of labels no longer used

This entire section still needs a good re-think and more revisions.
For now, I just removed mention of the labels that have been changed.

* Repeat the statement about vendor modules

It's true that the section on what's covered mentioned that vendor
modules are not, but it seemed strange that it was not mentioned in
the section that is specifically about what's no covered.

* Edit for typos

Mostly fix capitalization and occasional missing hyphens.

* Add notices that cirq-rigetti is deprecated

* Small edits for grammar and clarity

* Move paragraph about hardware modules higher in the list

Putting the bullet item about hardware modules seems higher in the
list seems like it's better, so that the flow of concepts goes
somewhare more general to somewhat more specific.

* Trivial edits to rewrite a phrase & add formatting

* Fix trivial typos

* Partially rewrite support.md

Changes:

* There were 3 H1 headings, and at the same time, the first heading
  did not match what is in the TOC. I changed this to have one H1
  heading that matches the TOC text, made the remaining headings H2,
  and added a lead-in paragaraph

* Rewrote the section about using the issue tracker in attempt to be
  more specific and clear.

* Added a section about using the Q.C. Stack Exchange.

* Added a section about using email to contact us.

* Fix minor inconsistent heading content style

A trivial change to match the way other headings were written.

* Update triage description

Removed more no-longer-existing issue labels, and rewrote section on
stale issue/PR heading to be more succinct.

* Fix trivial typos

Capitalization and placement of colon characters.

* Run spell checker

* Fix a few more typos

* Fix a few more tiny typos

* Take out Tesseract for now

It has no Cirq interface, and it's a bit too early stage still.

* Update list of software

* Spell out LBL and ORNL

* Mildly edit another description

* Fix misspelled name

* Remove cirq-rigetti from list of example modules

It's not essential, and removing it now will help reduce the number of
places we have to update when we remove Rigetti altogether.

* Make note of deprecation status in more places

* Update the section on Python imports

This adds information about `isort`'s use in Cirq, now that PR #7181
has been merged and `isort` is used in the check/ scripts.

* Fix typo

* Shorten the import ordering section

---------

Co-authored-by: Pavol Juhas <juhas@google.com>

Author: mhucka

docs/_book.yaml

@@ -239,7 +239,7 @@ upper_tabs:
         path: /cirq/dev/versions
       - title: "Triage process"
         path: /cirq/dev/triage
-      - title: "Issues / requests / questions"
+      - title: "Issues, requests, and questions"
         path: /cirq/dev/support
 
     - name: "Reference"

docs/build/_index.yaml

@@ -40,7 +40,7 @@ landing_page:
       description: Build and measure observables from sums and products of Pauli operators.
       path: /cirq/build/pauli_observables
     - heading: Qudits
-      description: Qutrits and higher dimensional quantum systems.
+      description: Qutrits and higher-dimensional quantum systems.
       path: /cirq/build/qudits
     - heading: Protocols
       description: Magic methods supported by Cirq's classes.

docs/build/ecosystem.md

@@ -1,59 +1,66 @@
-The following document provides an ecosystem overview of how the various tools compatible with Cirq can work together to enable quantum computing research.
+# Research libraries and tools
+
+The following document provides an ecosystem overview of various open-source tools compatible with Cirq and that can work together to enable quantum computing research.
 
 ![image alt text](../images/ecosystem.png)
 
-* **Research Libraries and Tools:** Libraries and tools used for researching new quantum algorithms and designing and preparing experiments on quantum devices.
+* **Research Libraries and Tools**: Libraries and tools used for researching new quantum algorithms and designing and preparing experiments on quantum devices.
 
 * **Cirq**: A framework specifically for programming noisy intermediate-scale quantum computers.
 
-* **Quantum Cloud Services:** Cirq can connect to a variety of quantum cloud services. Behind each cloud service, quantum algorithms run on either a quantum processor or simulator.
+* **Quantum Cloud Services**: Cirq can connect to a variety of quantum cloud services. Behind each cloud service, quantum algorithms run on either a quantum processor or simulator.
 
-* **Quantum Circuit Simulators:** Cirq is compatible with a number of quantum circuit simulators that can run either locally or in a distributed fashion.
-
-# Research libraries and tools
+* **Quantum Circuit Simulators**: Cirq is compatible with a number of quantum circuit simulators that can run either locally or in a distributed fashion.
 
 ## Algorithm libraries and experiments
 
 |Name|Main sponsor|Description|
 |--- |--- |--- |
-|[Cirq](https://github.com/quantumlib/Cirq)|Google|An open-source framework for creating, editing, and invoking Noisy Intermediate-Scale Quantum (NISQ) circuits.|
-|[OpenFermion](https://github.com/quantumlib/OpenFermion)|Google|An open-source algorithms library for developing new quantum chemistry and materials simulation algorithms|
-|[TensorFlow Quantum](https://tensorflow.org/quantum)|Google|An open-source algorithms library for developing new quantum machine learning algorithms|
-|[Qualtran](https://github.com/quantumlib/qualtran)|Google|An open-source library for expressing and analyzing fault-tolerant quantum algorithms|
-|[Stim](https://github.com/quantumlib/stim)|Google|An open-source library for high-speed simulation of Clifford circuits and quantum error correction|
-|[ReCirq](https://github.com/quantumlib/ReCirq)|Google|An open-source repository of example experiments, tools, and tutorials in quantum computing|
-|[Forge](https://forge.qcware.com/)|QCWare|A proprietary library for domain-specific quantum algorithms and applications|
-|[Pennylane](https://pennylane.ai/)|Xanadu|An open-source library for quantum machine learning with TensorFlow, PyTorch, or NumPy|
+|[Cirq](https://github.com/quantumlib/Cirq)|Google|A framework for creating, editing, and invoking Noisy Intermediate-Scale Quantum (NISQ) circuits.|
+|[OpenFermion](https://github.com/quantumlib/OpenFermion)|Google|An algorithms library for developing new quantum chemistry and materials simulation algorithms|
+|[Qualtran](https://github.com/quantumlib/qualtran)|Google|A library for expressing and analyzing fault-tolerant quantum algorithms|
+|[ReCirq](https://github.com/quantumlib/ReCirq)|Google|A repository of example experiments, tools, and tutorials in quantum computing|
+|[Stim](https://github.com/quantumlib/stim)|Google|A library for high-speed simulation of Clifford circuits and quantum error correction|
+|[TensorFlow Quantum](https://tensorflow.org/quantum)|Google|A library for developing new quantum machine learning algorithms|
+|[unitary](https://github.com/quantumlib/unitary)|Google|An API library providing common operations for adding quantum behaviors to games|
+|[Pennylane](https://pennylane.ai/)|Xanadu|A library for quantum machine learning with TensorFlow, PyTorch, or NumPy|
 
 ## Development tools
 
 |Name|Main sponsor|Description|
 |--- |--- |--- |
-|[Mitiq](https://github.com/unitaryfund/mitiq)|Unitary Foundation|An open-source library for error mitigation|
-|[pyGSTi](https://www.pygsti.info/)|Sandia National Labs|An open-source library for modeling and characterizing noisy quantum information processors|
-|[QUEKO](https://github.com/UCLA-VAST/QUEKO-benchmark)|UCLA|An open-source tool to generate benchmarks with the known optimal solutions|
-|[tket](https://cqcl.github.io/tket/pytket/api/index.html)|Cambridge Quantum|An open-source and platform agnostic SDK for circuit optimisation, compilation and noise mitigation|
-|[True-Q](https://trueq.quantumbenchmark.com/)|Quantum Benchmark|A proprietary library for assessing and optimizing quantum hardware and algorithm performance.|
+|[BQSKit](https://bqskit.lbl.gov/)|Lawrence Berkeley Labs|A portable quantum compiler framework with circuit optimization, synthesis, and gate set transpilation|
+|[Mitiq](https://github.com/unitaryfund/mitiq)|Unitary Foundation|A library for error mitigation|
+|[pyGSTi](https://www.pygsti.info/)|Sandia National Labs|A library for modeling and characterizing noisy quantum information processors|
+|[Qristal](https://github.com/qbrilliance/qristal)|Quantum Brilliance|A library for designing, optimizing, simulating and running hybrid quantum programs|
+|[Quantum Programming Studio](https://quantum-circuit.com/)|Quantastica|Web system for constructing and simulating quantum algorithms|
+|[QUEKO](https://github.com/UCLA-VAST/QUEKO-benchmark)|UCLA|A tool for generating benchmarks with known optimal solutions|
+|[QuTiP](https://github.com/qutip)|QuTiP|Toolbox for user-friendly and efficient numerical simulations of a wide variety of Hamiltonians|
+|[staq](https://github.com/softwareQinc/staq)|softwareQ Inc|C++ library for the synthesis, transformation, optimization, and compilation of quantum circuits|
+|[Superstaq](https://github.com/Infleqtion/client-superstaq/tree/main)|Infleqtion|An SDK that optimizes the execution of quantum programs by tailoring to underlying hardware primitives|
+|[tket](https://docs.quantinuum.com/tket/index.html)|Quantinuum|A platform-agnostic SDK for circuit optimization, compilation and noise mitigation|
+|[XACC](https://github.com/ORNL-QCI/xacc)|Oak Ridge National Labs|Extensible compilation framework using a novel, polymorphic quantum intermediate representation|
 
-## Supported quantum cloud services
+## Quantum computing cloud services
 
 |Company|Type of Quantum Computer|
 |--- |--- |
 |[Alpine Quantum Technologies](https://quantumai.google/cirq/hardware/aqt/getting_started)|Trapped ions|
 |[IonQ](https://quantumai.google/cirq/hardware/ionq/getting_started)|Trapped ions|
+|[IQM](https://iqm-finland.github.io/cirq-on-iqm/)|Superconducting qubits|
 |[Microsoft Azure Quantum](https://quantumai.google/cirq/hardware/azure-quantum/getting_started_ionq)|Trapped ions (Honeywell and IonQ)|
 |[Pasqal](https://quantumai.google/cirq/hardware/pasqal/getting_started)|Neutral atoms|
-|[Rigetti](https://quantumai.google/cirq/hardware/rigetti/getting_started)|Superconducting qubits|
 
-For more information for vendors about integrating with cirq,
+For more information for vendors about integrating with Cirq,
 see our [RFC page](../dev/rfc_process.md#new_hardware_integrations).
 
 ## High performance quantum circuit simulators
 
 |Name|Main sponsor|Description|
 |--- |--- |--- |
-|[qsim](https://github.com/quantumlib/qsim)|Google|An open-source, high-performance circuit simulator for Schrödinger simulations|
-|[quimb](https://github.com/jcmgray/quimb)|Johnny Gray|An open-source, high-performance circuit simulator using tensor-networks|
-|[qulacs](https://github.com/qulacs/cirq-qulacs)|Quansys|An open-source, high-performance circuit simulator for Schrödinger simulations|
-|[Stim](https://github.com/quantumlib/stim)|Google|An open-source library for high-speed simulation of Clifford circuits and quantum error correction|
-|[cuQuantum](https://developer.nvidia.com/cuquantum-sdk)|Nvidia|Tools for speeding up quantum simulation on GPUs|
+|[Qibo](https://qibo.science/)|Technology Innovation Institute|API library for hardware-accelerated quantum simulation and quantum hardware control|
+|[qsim](https://github.com/quantumlib/qsim)|Google|A high-performance circuit simulator for Schrödinger simulations|
+|[quimb](https://github.com/jcmgray/quimb)|Johnnie Gray|A high-performance circuit simulator using tensor-networks|
+|[qulacs](https://github.com/qulacs/cirq-qulacs)|Quansys|A high-performance circuit simulator for Schrödinger simulations|
+|[Stim](https://github.com/quantumlib/stim)|Google|A library for high-speed simulation of Clifford circuits and quantum error correction|
+|[cuQuantum](https://github.com/NVIDIA/cuQuantum)|NVIDIA|API libraries for speeding up quantum simulation on NVIDIA GPUs|

docs/citation.md

@@ -11,3 +11,4 @@ When using our projects, please cite them according to the following guide:
 | ReCirq | https://github.com/quantumlib/ReCirq#how-to-cite-recirq |
 | Stim | https://github.com/quantumlib/stim#how-cite-stim |
 | Tensorflow Quantum | https://github.com/tensorflow/quantum#references|
+| Tesseract Decoder | https://github.com/quantumlib/tesseract-decoder#citation|

docs/dev/development.md

@@ -15,7 +15,7 @@ cd Cirq
 
 ## Recommended git setup
 
-The following command will setup large refactoring revisions to be ignored, when using git blame.
+The following command will set up large refactoring revisions to be ignored, when using git blame.
 
 ```
 git config blame.ignoreRevsFile .git-blame-ignore-revs
@@ -24,7 +24,7 @@ git config blame.ignoreRevsFile .git-blame-ignore-revs
 Note that if you are using PyCharm, you might have to use the command Restart & Invalidate Caches to have the change be picked up.
 
 ## Docker
-You can build the stable and pre_release Docker images with our `Dockerfile`.
+You can build the stable and pre-release Docker images with our `Dockerfile`.
 
 ```bash
     docker build -t cirq --target cirq_stable .
@@ -105,11 +105,10 @@ See the previous section for instructions.
     Docker or configure permissions on your system; see the
     [Docker installation instructions](https://docs.docker.com/engine/install/ubuntu/)
     for more information.
-    Note that Docker is necessary only for the `cirq-rigetti` module.
 
     There are some extra steps if Protocol Buffers are changed; see the next section.
 
-2. Prepare a virtual environment including the dev tools (such as Mypy).
+2. Prepare a Python virtual environment that includes the Cirq dev tools (such as Mypy).
 
     One of the system dependencies we installed was `virtualenvwrapper`, which makes it easy to create virtual environments.
     If you did not have `virtualenvwrapper` previously, you may need to re-open your terminal or run `source ~/.bashrc` before these commands will work:
@@ -123,7 +122,7 @@ See the previous section for instructions.
 
     (When you later open another terminal, you can activate the virtualenv with `workon cirq-py3`.)
 
-    **Note:** Some highly managed or customized devices have configurations that interfere with `virtualenv`.
+    **Note**: Some highly managed or customized devices have configurations that interfere with `virtualenv`.
     In that case, [anaconda](https://www.anaconda.com/) environments may be a better choice.
 
 3. Check that the tests pass.
@@ -147,7 +146,7 @@ See the previous section for instructions.
     ```bash
     add2virtualenv <paste modules from last command>
     ```
-    (Typically `add2virtualenv` is not executable using xargs, so this two step process is necessary.)
+    (Typically `add2virtualenv` is not executable using `xargs`, so this two step process is necessary.)
 
 ## Editable installs
 

docs/dev/gates.md

@@ -46,7 +46,7 @@ In some cases the default behavior of using `__str__` is sufficient.
 
 4. If the `__repr__` is cumbersome, gates should specify a `_repr_pretty_`
 method.
-This method will be used preferentially by Jupyter notebooks, ipython, etc.
+This method will be used preferentially by Jupyter notebooks, iPython, etc.
 
 5. Gates should specify an `_apply_unitary_` method.
 This is not necessary for single or two qubit gates, but it is a huge
@@ -62,6 +62,6 @@ generally surprising to users.
 If you have to use an operation, try to have the `.gate` property of the
 operation can return something useful instead of `None`.
 
-8. Consider adding interop methods like `_qasm_`.
+8. Consider adding interoperability methods like `_qasm_`.
 These methods will fallback to using things like `_decompose_`, but the output
 is usually much better when specialized.

docs/dev/modules.md

@@ -1,6 +1,6 @@
 # Cirq modules
 
-Cirq has a modular architecture and is organized in a monorepo, all of the modules follow the same folder structure.
+Cirq has a modular architecture and is organized in a monorepo. All of the modules follow the same folder structure.
 Each module is structured as follows. Let's take as example a module named `cirq-example`:
 
 ```
@@ -21,14 +21,14 @@ cirq-example
 
 Note that typically there is only a single top level package, `cirq_example` - but there might be exceptions.
 
-Additionally, there is a metapackage "cirq" that's a completely different beast and just depends on the modules.
+Additionally, there is a metapackage named `cirq` that's a completely different beast and just depends on the modules.
 This enables `pip install cirq` to have all the included modules to be installed for our users.
 
 All modules should depend on `cirq-core`, which is the central, core library for Cirq.
 
 ## Packaging
 
-Each package gets published to PyPi as a separate package. To build all the wheel files locally, use
+Each package gets published to PyPI as a separate package. To build all the wheel files locally, use
 
 ```bash
 dev_tools/packaging/produce-package.sh ./dist `./dev_tools/packaging/generate-dev-version-id.sh`
@@ -38,13 +38,13 @@ Packages are versioned together, share the same version number, and are released
 
 ## Setting up a new module
 
-To setup a new module follow these steps:
+To set up a new module follow these steps:
 
 1. Create the folder structure above, copy the files based on an existing module
-    1. LICENSE should be the same
-    2. README.md will be the documentation that appears in PyPi
-    3. setup.py should specify an `install_requires` configuration that has `cirq-core=={module.version}` at the minimum
-2. Setup JSON serialization for each top level python package
+    1. The `LICENSE` file should be the same
+    2. The `README.md` file will be the documentation that appears in PyPI
+    3. The `setup.py` file should specify an `install_requires` configuration that has `cirq-core=={module.version}` at the minimum
+2. Set up JSON serialization for each top level Python package
 
 
 ### Setting up JSON serialization
@@ -85,7 +85,7 @@ To setup a new module follow these steps:
        ```
    2. `__init__.py` should import `TestSpec` from `spec.py`
    3. in `cirq/protocols/json_serialization_test.py` add `'cirq_example':None` to the `TESTED_MODULES` variable. `TESTED_MODULES` is also used to prepare the test framework for deprecation warnings.
-      With new modules, we use`None` as there is no deprecation setup.
+      With new modules, we use `None` as there is no deprecation setup.
 
 You can run `check/pytest-changed-files` and that should execute the script `json_serialization_test.py` as well.
 

docs/dev/notebooks.md

@@ -62,7 +62,7 @@ them to `SKIP_NOTEBOOKS` within the file `dev_tools/notebooks/notebook_test.py`.
 
 External dependencies, for these purposes, are calls to external services and
 APIs, such as vendor endpoints for cloud services.  These can also include
-external downloads, such as installing packages from unknown debian
+external downloads, such as installing packages from unknown Debian
 repositories, which may be blocked for security reasons.
 
 The site that generates the outputs for notebooks also can't handle external dependencies.
@@ -71,7 +71,7 @@ Thus, for notebooks with external dependencies, **all cells must have their outp
 
 ## Lifecycle
 
-You should configure notebooks differently depending on whether they rely on features in the pre-release build of cirq or not.
+You should configure notebooks differently depending on whether they rely on features in the pre-release build of Cirq or not.
 
 ### Pre-release notebooks
 

docs/dev/plotting.md

@@ -8,7 +8,7 @@ Here we recommend the input arguments, return value, and behavior of the
 1. **Convenience to interactive users.** This is the highest priority.
     Compared to being called in a batch script as a library (for composing
     more complicated plots or other purposes), the `plot` method is mainly
-    used in interactive sessions like ipython, Jupyter, Colab, PyCharm,
+    used in interactive sessions like iPython, Jupyter, Colab, PyCharm,
     and the Python interpreter.
 1. **Plot is customizable.** The plot should be customizable by the user after
     `plot` returns. This is important because user may need to change the look
@@ -45,7 +45,7 @@ class Foo:
 ```
 
 This `plot` method works in 2 modes: *memory mode* and *interactive mode*,
-signalled by the presence of the `ax` argument. When present, the method is
+signaled by the presence of the `ax` argument. When present, the method is
 instructed to plot on the provided `ax` instance in memory. No plot is shown
 on the screen. When absent, the code is in *interactive* mode, and it creates
 a figure and shows it.