We have shown that the coupling of a coherent exciton–photon system to an m-photon two-level atom may produce both quadrature-amplitude and number-phase squeezed excitons.
The phase-modulated quadrature squeezing in the system that composed of two coupled cavities interacting with a two-level atom is investigated. The variances of the amplitude and phase quadrature of the output field are calculated. It turns out that the squeezing behaviors of the output field can be obviously modified due to the phase difference of the coupling strengths between the atom and the two cavities. The squeezing in one quadrature (i.e., phase quadrature) can be transferred into another (i.e., amplitude quadrature), or the quadrature squeezing located at the low-frequency region can be transferred into the high-frequency region by modulating the relative phase of the coupling strengths. Furthermore, the effects of the decay mismatch between the two cavities and the coupling mismatch between the atom and the cavities on the quadrature squeezing have been discussed. The results show that both the decay mismatch and the coupling mismatch play a positive role in generating better quadrature squeezing.
We investigate higher-order exceptional points and quantum squeezing of exciton polaritons in a pseudo-Hermitian semiconductor optomechanical system. We show that a third-order exceptional point (EP3) can emerge from the tripartite coupling among photons, excitons, and phonons under pseudo-Hermitian conditions. A pronounced two-mode quantum squeezing of exciton polaritons is revealed, and we demonstrate that this squeezing is significantly enhanced in the vicinity of the EP3. Furthermore, we find that in the PT-symmetric phase, the squeezing dynamics produce a frequency comb of exciton polaritons, whereas the squeezing remains constant over time in the PT-symmetry broken phase and exactly at the EP3. The sudden change in quantum squeezing dynamics can be used to probe the phase transition and the EP3. Our work opens a pathway to manipulate quantum squeezing in semiconductor optomechanical platforms, offering potential advantages for quantum sensing and metrology.
Signal and idler waves produced by a nondegenerate parametric amplifier feature strong positive correlation between their photon numbers, or in-phase amplitudes. They feature equally strong negative correlation between their phases, or quadrature-phase amplitudes. These photon twins can produce arbitrarily squeezed states via state reduction by appropriate measurements of an idler wave. When the quadrature amplitude of an idler wave is measured, the signal wave is collapsed to a quadrature-amplitude squeezed state. When the two-quadrature amplitudes of an idler wave are measured simultaneously, the signal wave becomes a coherent state.