Static MPFs (qiskit_addon_mpf.static)

Static MPF coefficients.

This module provides the generator function for the linear system of equations (LSE) for computing static (that is, time-independent) MPF coefficients.

setup_static_lse(trotter_steps, *, order=1, symmetric=False)[source]

Return the linear system of equations for computing static MPF coefficients.

This function constructs the following linear system of equations:

\[A x = b,\]

with

\[\begin{split}A_{0,j} &= 1 \\ A_{i>0,j} &= k_{j}^{-(\chi + s(i-1))} \\ b_0 &= 1 \\ b_{i>0} &= 0\end{split}\]

where $\chi$ is the order, $s$ is $2$ if symmetric is True and $1$ oterhwise, $k_{j}$ are the trotter_steps, and $x$ are the variables to solve for. The indices $i$ and $j$ start at $0$.

Here is an example:

>>> from qiskit_addon_mpf.static import setup_static_lse
>>> lse = setup_static_lse([1,2,3], order=2, symmetric=True)
>>> print(lse.A)
[[1.         1.         1.        ]
 [1.         0.25       0.11111111]
 [1.         0.0625     0.01234568]]
>>> print(lse.b)
[1. 0. 0.]
Parameters:

  • trotter_steps (list[int] | Parameter) – the sequence of trotter steps from which to build $A$. Rather than a list of integers, this may also be a Parameter instance of the desired size. In this case, the constructed LSE is parameterized whose values must be assigned before it can be solved.

  • order (int) – the order of the individual product formulas making up the MPF.

  • symmetric (bool) –

    whether the individual product formulas making up the MPF are symmetric. For example, the Lie-Trotter formula is not symmetric, while Suzuki-Trotter is.

    Note

    Making use of this value is equivalent to the static MPF coefficient description provided by [1]. In contrast, [2] disregards the symmetry of the individual product formulas, effectively always setting symmetric=False.

Returns:

The LSE to find the static MPF coefficients as described above.

Return type:

LSE

References

[1]: A. Carrera Vazquez et al., Quantum 7, 1067 (2023).

https://quantum-journal.org/papers/q-2023-07-25-1067/

[2]: S. Zhuk et al., Phys. Rev. Research 6, 033309 (2024).

https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.033309