Creation and Detection of Entanglement

S. Ya. Kilin, Alexander B. Mikhalychev, Alexander P. Nizovtsev +3 more

We consider creation and detection of GHZ state of one electronic and two nuclear spins of carbon isotopes 13C in the first coordination shell of NV center in diamond. The method of entanglement detection is based on construction of an entanglement witness operator.

Otfried Gühne, Géza Tóth

Adam Bednorz, Wolfgang Belzig

The creation and detection of entanglement in solid state electronics is of fundamental importance for quantum information processing. We prove that second-order quantum correlations can be always interpreted classically and propose a general test of entanglement based on the violation of a classically derived inequality for continuous variables by fourth-order quantum correlation functions. Our scheme provides a way to prove the existence of entanglement in a mesoscopic transport setup by measuring higher order cumulants without requiring the additional assumption of a single-charge detection.

Barbara M. Terhal

Johannes Ferber, Frank K. Wilhelm

We investigate three superconducting flux qubits coupled in a loop. In this setup, tripartite entanglement can be created in a natural, controllable, and stable way. Both generic kinds of tripartite entanglement--the W type as well as the GHZ type entanglement--can be identified among the eigenstates. We also discuss the violation of Bell inequalities in this system and show the impact of a limited measurement fidelity on the detection of entanglement and quantum nonlocality.