Tensor network decompositions for absolutely maximally entangled states
Absolutely maximally entangled (AME) states of k qudits are quantum
states that have maximal entanglement for all possible bipartitions of
the sites/parties, and they can also be interpreted as perfect
tensors. We consider the problem of whether such states can be
decomposed into a tensor network with a small number of tensors, such
that all physical and all auxiliary spaces have the same dimension
D. We find that certain AME states with k=6 can be decomposed
into a network with only three 4-leg tensors; we provide concrete
solutions for local dimension D=5 and higher. Our result implies
that certain AME states with six parties can be created with only
three two-site unitaries from a product state of three Bell pairs, or
equivalently, with six two-site unitaries acting on a product state on
six qudits. We also consider the problem for k=8, where we find
similar tensor network decompositions with six 4-leg tensors.