Squeezed Coherent States in Double Optical Resonance

In this work, we consider a “Λ-type” three-level system where the first transition is driven by a radiation field initially prepared in a squeezed coherent state, while the second one by a weak probe field. If the squeezed field is sufficiently strong to cause Stark splitting of the states it connects, such a splitting can be monitored through the population of the probe state, a scheme also known as “double optical resonance”. Our results deviate from the well-studied case of coherent driving indicating that the splitting profile shows great sensitivity to the value of the squeezing parameter, as well as its phase difference from the complex displacement parameter. The theory is cast in terms of the resolvent operator where both the atom and the radiation field are treated quantum mechanically, while the effects of squeezing are obtained by appropriate averaging over the photon number distribution of the squeezed coherent state.

Effect of the oscillations in the photon distribution of a squeezed field on the fluorescence spectrum of the Jaynes–Cummings model

Following the scheme proposed by Eberly and Wodkiewicz for the physical spectrum, we calculate the fluorescence spectrum of the Jaynes–Cummings model when the two-level system interacts with an electromagnetic field that initially is in a squeezed coherent state. We show the appearing of “ringing lines” in the fluorescence spectrum that are echoes of the oscillations in the photon distribution of the compressed field. These ringing lines may be a similar effect as the ringing revivals of the atomic inversion that are a signature of squeezed states.

Nonclassical properties of the squeezing and rotating coherent state

In this paper, we construct and investigate the nonclassical properties of the squeezing and rotating coherent state (SRCS) via a generalized squeezed operator by introducing a novel parameter r. In a particular case r = 0, SRCS reduces to the normal squeezed coherent state (SCS). The influence of r is studied in terms of squeezing and quantum statistical properties. Our results show that in the SCS not only is squeezing enhanced but also is rotated by the parameter r. Our discussion about the fidelity between SRCS and SCS shows that the fidelity values decrease with increasing parameter r. The experimental scheme for producing SRCS is also given via a self-Kerr medium and non-degenerate parametric amplifier.

Exploring Chaos and Entanglement in the Hénon–Heiles System Using Squeezed Coherent States

Quantum entanglement in the Hénon–Heiles system is analyzed using the squeezed coherent state. Enhancement of quantum entanglement via squeezing is explored in connection with chaotic and regular dynamics of the system. It is found that the entanglement enhancement via squeezing is implicitly linked to the local structure of the classical phase-space and it shows a clear quantum-classical correspondence. In particular, the entanglement enhancement via squeezing is found to be negligible for a highly chaotic orbit compared to the regular and weakly chaotic orbits, and shows a clear correspondence to the degree of chaos present in the classical initial condition. We believe that these results might be useful to develop efficient strategies to enhance entanglement in quantum systems.