Investigate support for SymEngine as an alternative to SymPy #7900
Description
Is your feature request related to a use case or problem? Please explain
At the request of @ikd-sci, we should look at SymEngine as a fast alternative to SymPy. It's written in C++, and while the build process looks involved, wheels for many platforms are available.
Describe the solution you would prefer
Testing should be carefully done for compatibility with Cirq's current code.
How urgent is this for you? Is it blocking important work?
P2 – we should do it in the next couple of quarters