Tomography, control, and characterization of entanglement in a three-level atomic system

作者：Sandhya S N^*; Ravishankar V

来源：Physical Review A, 2010, 82(6): 062301.

DOI：10.1103/PhysRevA.82.062301

We study the quantum correlations of the radiation emitted by three-level atoms (cascade type) interacting with two driving fields. In the linear regime, and in the Weisskopf-Wigner approximation, we show that the atomic and the two-photon density matrix are equivalent to each other. This facilitates the tomography of the two-mode state to be realized by measurements on either the atomic system or the emitted fields. While, in general, one needs 4(N) measurements for the tomography of an N-photon state, we show that one needs (N + 1)(2) - 1 observables for the tomography of photons emitted by an atomic system. Thus there is an exponential reduction in the number of observables for the reconstruction of the class of N-photon states emitted by atoms. We show that the driving field strengths and detunings provide the control parameters for the preparation of a specific target state. Finally, we study the characterization of entanglement of the two-photon state. We observe that a characterization of entanglement in terms of a single parameter is not possible when the system is in a mixed state; therefore, we provide a description in terms of the newly introduced probability distribution for entanglement, in various regimes of interest.

• 出版日期2010-12-2