Add Qiskit example on mitigating the energy landscape of a variational circuit

[Rahul-Mistri]

Issue Description

The example Mitigating the energy landscape of a variational circuit with Mitiq is implemented using Cirq as a frontend. We ought to implement this using Qiskit as an example for our users.

Proposed Solution

• Implement a Qiskit variant of the example (the source can be found here)

Additional References

• Please consult the contributing guidelines for specific details on contributing to the documentation, and the general contributing guidelines as well.

[nickdgardner]

I can work on this issue

[nickdgardner]

@natestemen Here is my initial notebook for this issue. I thought I'd upload it here for feedback/review before submitting a PR to change the documentation, but let me know if I should do something else. Thanks!

https://github.com/nickdgardner/mitiq/blob/master/docs/source/examples/simple-landscape-qiskit.ipynb https://github.com/nickdgardner/mitiq/blob/master/docs/source/examples/simple-landscape-qiskit.myst

[natestemen]

Nice work Nick! I'd say just go ahead and open a PR and I can start giving you more concrete feedback from there.