We provide a class of inequalities whose violation shows the presence of entanglement in two-mode systems. We initially consider observables that are quadratic in the mode creation and annihilation operators and find conditions under which a two-mode state is entangled. Further examination allows us to formulate additional conditions for detecting entanglement. We conclude by showing how the methods used here can be extended to find entanglement in systems of more than two modes.
Physical Review Letters
- Pub Date:
- February 2006
- Entanglement production characterization and manipulation;
- Entanglement and quantum nonlocality;
- Quantum Physics
- 4 pages, replaced with published version