Paper detail

Group structures and representations of graph states

A special configuration of graph state stabilizers, which contains only Pauli $σ_X$ operators, is studied. The vertex sets $ξ$ associated with such configurations are defined as what we call X-chains of graph states. The X-chains of a general graph state can be determined efficiently. They form a group structure such that one can obtain the explicit representation of graph states in the X-basis via the so-called X-chain factorization diagram. We show that graph states with different X-chain groups can have different probability distributions of X-measurement outcomes, which allows one to distinguish certain graph states with X-measurements. We provide an approach to find the Schmidt decomposition of graph states in the X-basis. The existence of X-chains in a subsystem facilitates error correction in the entanglement localization of graph states. In all of these applications, the difficulty of the task decreases with increasing number of X-chains. Furthermore, we show that the overlap of two graph states can be efficiently determined via X-chains, while its computational complexity with other known methods increases exponentially.