Non-separated states from squeezed dark-state polaritons in electromagnetically-induced-transparency media

Within the frame of quantized dark-state polaritons in electromagnetically-induced-transparency media, noise fluctuations in the quadrature components are studied. Squeezed state transfer, quantum correlation, and noise entanglement between probe field and atomic polarization are demonstrated in single- and double-$\Lambda$ configurations, respectively. Even though a larger degree of squeezing parameter in the continuous variable helps to establish stronger quantum correlations, inseparability criterion is satisfied only within a finite range of squeezing parameter. The results obtained in the present study may be useful for guiding experimental realization of quantum memory devices for possible applications in quantum information and computation.Comment: 12 pages, 7 figure

Gain-assisted quantum heat engine based on electromagnetically induced transparency

We present a scheme to realize a gain-assisted quantum heat engine (QHE) based on electromagnetically induced transparency (EIT). We consider a three-level { \Lambda}-type atomic system that interacts with two thermal reservoirs and a coupling field. The gain without inversion is induced in the system via spontaneously generated coherence (SGC) between two lower levels. To generate SGC, some rigorous conditions must be maintained, but its effect on the system's dynamics are significant, resulting in an enhancement of the emission cross-section and spectral brightness of the QHE