seemps.operators.MPOList#

class seemps.operators.MPOList#

Bases: object

Sequence of matrix-product operators.

This implements a list of MPOs that are applied sequentially. It can impose its own truncation or simplification strategy on top of the one provided by the individual operators.

Parameters:

mposlist[MPO]: Operators in this sequence, to be applied from mpos[0] to mpos[-1]. Must contain at least one operator.
strategyStrategy, optional: Truncation and simplification strategy, defaults to DEFAULT_STRATEGY

Attributes

mpos	(list[MPO]) Operators in this sequence, to be applied from mpos[0] to mpos[-1]. Must contain at least one operator.
strategy	(Strategy) Truncation and simplification strategy.
size	(int) Number of quantum subsystems in each MPO. Computed from the supplied MPOs. Not checked for consistency.

property T: MPOList#: Return the transpose of this operator.

apply(state: MPS, strategy: Strategy | None = None, simplify: bool | None = None) → MPS[source]#

apply(state: MPSSum, strategy: Strategy | None = None, simplify: bool | None = None) → MPS | MPSSum

Implement multiplication A @ state between a matrix-product operator A and a matrix-product state state.

Parameters:

stateMPS | MPSSum: Transformed state.
strategyStrategy, optional: Truncation strategy, defaults to DEFAULT_STRATEGY
simplifybool, optional: Whether to simplify the state after the contraction. Defaults to strategy.get_simplify_flag()

Returns:

CanonicalMPS: The result of the contraction.

conj() → MPOList[source]#: Return the complex conjugate of this operator.

copy() → MPOList[source]#: Shallow copy of the MPOList, without copying the MPOs themselves.

dimensions() → list[int][source]#: Return the physical dimensions (Deprecated, see dimensions()).

expectation(bra: MPS, ket: TypeAliasForwardRef('~seemps.state.MPS') | None = None) → Weight[source]#

Expectation value of MPOList on one or two MPS states.

If one state is given, this state is interpreted as \(\psi\) and this function computes \(\langle{\psi|O\psi}\rangle\) If two states are given, the first one is the bra \(\psi\), the second one is the ket \(\phi\), and this computes \(\langle\psi|O|\phi\rangle\).

Parameters:

braMPS: The state \(\psi\) on which the expectation value is computed.
ketMPS | None: The ket component of the expectation value. Defaults to bra.

Returns:

float | complex: \(\langle\psi\vert{O}\vert\phi\rangle\) where O is the matrix-product operator.

extend(L: int, sites: list[int] | None = None, dimensions: int | list[int] = 2) → MPOList[source]#

Enlarge an MPOList so that it acts on a larger Hilbert space with ‘L’ sites.