Dbi non classical simulation

[shangtai]

Hi,

This is an implementation of the scenario where classical simulation is not possible for first order product formula.

Scenario B: Classical simulation is not possible.

We may use the bound
$$||Q(s) - U(s) || = \sum_{i=1}^N ||[h_i,h_{i+1}|| s^2 \le C_h s^2 N$$
where $C_h = max_i ||[h_i,h_{i+1}||$

Set $N = \epsilon / (C_h s^2)$

Checklist:

• Reviewers confirm new code works as expected.
• Tests are passing.
• Coverage does not decrease.
• Documentation is updated.