BreuerState

BreuerState is a function that produces a two-qudit "Breuer state" (i.e., the state defined in ). These states are of interest because they are bound entangled. The output of this function is sparse.

Syntax

 * BREUER_STATE = BreuerState(DIM,LAMBDA)

Argument descriptions

 * DIM: The local dimension (must be &ge; 2 and even).
 * LAMBDA: The weight of the singlet component in the state (see for details). A positive real number between 0 and 1. The state will be separable if and only if LAMBDA = 0 and it will have positive partial transpose if and only if LAMBDA <= 1/(DIM + 2)).

A 4 &#8855; 4 bound entangled state
The following code generates a bound entangled Breuer state in $M_4 \otimes M_4$ and then verifies that has positive partial transpose and is entangled (and is thus bound entangled):