OTOC example tutorial fails to run

[mhucka]

Describe the issue

The tutorial notebook at https://quantumai.google/cirq/experiments/otoc/otoc_example fails to run in Cirq after Cirq 1.3. This started happening after we updated the Cirq version dependency in ReCirq because the class PhasedFSimEngineSimulator was removed by Cirq PR #6442 and does not exist in Cirq 1.4+.

How can the issue be reproduced?

Attempting to run the tutorial in Colab demonstrates the failure. The failing code is

processor_id = ""
use_noisy_simulator = use_noisy_simulator or processor_id == "" 
if use_noisy_simulator:
    print("Using a noisy simulator.")
    sampler = cg.PhasedFSimEngineSimulator.create_with_random_gaussian_sqrt_iswap(
        mean=cg.SQRT_ISWAP_INV_PARAMETERS,
        sigma=cg.PhasedFSimCharacterization(
            theta=0.01, zeta=0.10, chi=0.01, gamma=0.10, phi=0.02
        ),
    )
    device = cg.Bristlecone
else:
    sampler = cg.get_engine_sampler(processor_id, gate_set_name="sqrt_iswap")
    device = cg.get_engine_device(processor_id=processor_id)

[Ammog-Warrier]

Hey there. Could I maybe work on this if it's fine?

[mhucka]

@Ammog-Warrier Thank you for your interest. It turns out I had actually more or less solved this but had not gotten so far as to get it into ReCirq, and now I see I never assignmed myself to this issue to show it was being worked on. My apologies for the poor handling of this. Let me take stock of the status, open a PR, and if there's still more to do, I'll let you have the rest.