quantax.optimizer.ER

class quantax.optimizer.ER(state: Variational, hamiltonian: Operator, imag_time: bool = True, solver: Callable | None = None, symm: Symmetry | None = None)

Exact reconfiguration, performed by a full summation in the whole Hilbert space. This is only available in small systems.

__init__(state: Variational, hamiltonian: Operator, imag_time: bool = True, solver: Callable | None = None, symm: Symmetry | None = None)

Parameters:

• state – Variational state to be optimized.

• hamiltonian – The Hamiltonian for the evolution.

• imag_time – Whether to use imaginary-time evolution, default to True.

• solver – The numerical solver for the matrix inverse, default to auto_pinv_eig.

• symm – Symmetry used to construct the Hilbert space, default to be the symmetry of the variational state.

Methods

__init__(state, hamiltonian[, imag_time, ...])
get_Ebar(wave_function)	Compute \(\bar \epsilon\) in the full Hilbert space.
get_Obar(wave_function)	Compute \(\bar O\) in the full Hilbert space.
get_step()	Obtain the optimization step by solving the equation \(\bar O \dot \theta = \bar \epsilon\).
solve(Obar, Ebar)	Solve the equation \(\bar O \dot \theta = \bar \epsilon\) for given \(\bar O\) and \(\bar \epsilon\).

Attributes

energy	Energy of the current step.
hamiltonian	The Hamiltonian for the evolution.
holomorphic	Whether the state is holomorphic.
imag_time	Whether to use imaginary-time evolution.
state	Variational state to be optimized.
vs_type	The vs_type of the state.