Add information on new vendor setup (#5485)

* Add information on new vendor setup

- Add a blurb about submitting RFC and attending cirq cync
- Adds information about possible options and different pieces
needed for an integration.
- Links to this in two places.

docs/dev/rfc_process.md

@@ -105,5 +105,49 @@ While we encourage and celebrate every contributor, the bar for RFC acceptance i
 *   Failure to achieve consensus during the design review.
 *   Concerns raised during implementation (for example: inability to achieve backwards compatibility, concerns about maintenance).
 
-If this process is functioning well, RFCs are expected to fail in the earlier, rather than later stages. 
+If this process is functioning well, RFCs are expected to fail in the earlier, rather than later stages.
 An approved RFC is not a commitment to implementation on any sort of timeline. The prioritization of features depends on user interest and willingness of contributors to implement them.
+
+## New hardware integrations
+
+Several hardware vendors already have integrations with cirq.  We are not
+currently soliciting additional vendors.  However, if you are considering
+integrating with cirq, we would highly encourage you to engage with the
+cirq-maintainer team through attending the weekly cirq cync and submitting
+an RFC as specified above.  Everyone benefits from a well-maintained, user
+friendly interface with a high reliability, which is the goal of having this
+RFC process.
+
+Examples of other integrations can be found on the
+[Hardware page](/cirq/hardware).
+
+There are a range of possibilities for integrating with cirq, including:
+
+*    Completely independent repository: requires the least engagement from
+the cirq team, but also lacks the benefits of a tighter integration and
+partnership.
+*    Different repository with links or tutorials hosted on cirq:
+less coordination is needed than a hosted integration, but requires
+continuous integration on the external repository to ensure compatibility
+with new cirq versions.
+*    Integration hosted within cirq repository:  requires the highest
+amount of coordination and effort but allows a tighter integration and for
+cirq-maintainers to modify the integration code to stay in sync with an
+evolving cirq-core code base.  We generally do not accept submissions for
+this type of integration for third-party vendors that function as
+intermediaries for other cloud vendors.
+
+Several things are needed for a successful integration:
+
+*    Plan for including external dependencies (if needed).
+*    Access and authentication.
+*    Tutorials and guides for use of the interface (for instance,
+a Getting Started guide).
+*    `Device` implementation for validating circuits on the hardware
+*     Transformer for compiling circuits to the supported gates on the
+hardware (or use `cirq.optimize_for_target_gateset`)
+*    ` Sampler` interface for running circuits on the hardware service.
+*     Conisder also providing a noise model that users can use to simulate the
+device if direct access is not available.
+
+

docs/ecosystem.md

@@ -10,7 +10,7 @@ The following document provides an ecosystem overview of how the various tools c
 
 * **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 
+# Research libraries and tools
 
 ## Algorithm libraries and experiments
 
@@ -45,6 +45,10 @@ The following document provides an ecosystem overview of how the various tools c
 |[Pasqal](https://quantumai.google/cirq/tutorials/pasqal/getting_started)|Neutral atoms|
 |[Rigetti](https://quantumai.google/cirq/tutorials/rigetti/getting_started)|Superconducting qubits|
 
+For more information for vendors about integrating with cirq,
+see our [RFC page](/cirq/dev/rfc_process#new_hardware_integrations).
+
+
 ## High performance quantum circuit simulators
 
 |Name|Main sponsor|Description|

docs/hardware/_index.yaml

@@ -119,7 +119,7 @@ landing_page:
           name: menu_book
 
     - heading: Custom devices
-      description: How to write custom Device classes for quantum hardware.
+      description: How to write custom Device classes for quantum hardware. More information for vendors on integrating with cirq can be found on the RFC page.
       items:
       - heading: Neutral atom device
         description: A custom device class for a neutral atom device.