seemps.state.MPSSum

class seemps.state.MPSSum

Bases: object

Class representing a weighted sum (or difference) of two or more MPS.

This class is an intermediate representation for the linear combination of MPS quantum states. Assume that \(\psi, \phi\) and \(\xi\) are MPS and \(a, b, c\) some real or complex numbers. The addition \(a \psi - b \phi + c \xi\) can be stored as MPSSum([a, -b, c], [ψ, ϕ, ξ]).

Parameters:

weightslist[Weight]

Real or complex numbers representing the weights of the linear combination.

stateslist[MPS]

List of matrix product states weighted.

conj() → MPSSum

Return the complex-conjugate of this quantum state.

copy() → MPSSum

Return a shallow copy of the MPS sum and its data. Does not copy the states, only the list that stores them.

delete_zero_components() → float

Compute the norm-squared of the linear combination of weights and states and eliminate states that are zero or have zero weight.

error() → float

Upper bound of the norm-2 error accumulated in this MPS.

join() → MPS

Create an MPS by combining all tensors from all states in the linear combination.

Returns:

MPS

Quantum state approximating this sum.

join_canonical(*args, **kwdargs) → CanonicalMPS

Similar to join() but return canonical form

norm() → float

Norm-2 \(\Vert{\psi}\Vert^2\) of this MPS.

norm_squared() → float

Norm-2 squared \(\Vert{\psi}\Vert^2\) of this MPS.

physical_dimensions() → list[int]

List of physical dimensions for the quantum subsystems.

reverse() → MPSSum

Reverse the sites (see reverse()).

to_tensor() → Vector

Convert this MPS to a multidimensional tensor.

to_vector() → Vector

Return the wavefunction of this quantum state.