Dynamics and Entanglement Indicators in Bipartite CV Systems

We evaluate bipartite entanglement indicators defined directly from tomograms in two time-evolving continuous variable systems: a radiation field interacting with a nonlinear atomic medium modeled as an oscillator; and a double-well BEC, the atomic condensate in each well modeled by an oscillator Hamiltonian with appropriate nonlinear interactions. Under unitary evolution, the bipartite state is known to exhibit features similar to wave packet revivals. Specifically in the former model, while an unentangled bipartite initial state gets entangled at subsequent times, the entanglement dips periodically, nearly vanishing at certain instants. In both systems, the tomographic indicators are shown to compare favorably with standard entanglement measures, capturing all the interesting features of the entanglement dynamics. Moreover, despite decoherence introduced in the BEC system, the tomographic approach is successful in mirroring entanglement trends. Even though off-diagonal correlations in the density matrix are not explicitly seen in tomograms, the tomographic approach provides a viable alternative to standard entanglement assessors that involve state reconstruction.