Quantum Discord of pairs in Heisenberg spin chains

L. CILIBERTI; R. ROSSIGNOLI; N. CANOSA

Paraty

Otro; Quantum information School; 2011

Quantum Entanglement denotes quantum correlations without classical analogue. As is well known, it is a fundamental resource in Quantum Information Science, being essential for quantum teleportation and for achieving exponential speed-up in pure state based quantum computation. However, no substantial entanglement present in some quantum circuits based on mixed states, which still achieve exponential speed-up. An alternative measure of quantum correlations in mixed quantum states. Fully equivalent to entanglement for pure states, but may be non-zero in some separable mixed states. In this work we determine the QD of a spin pair in an anisotropic XY chain. We examine in detail the QD in the vicinity of the factorizing field, where full analytic expressions are provided. We show in particular that the QD reaches full range in its vicinity.