Occurrence Of Normal Mode Splitting Research Articles

Optomechanical Entanglement Between an Ion and an Optical Cavity Field

We study an optomechanical system in which the mechanical motion of a single trapped ion is coupled to a cavity field for the realization of a strongly quantum correlated two-mode system. We show that for large pump intensities the steady state photon number exhibits bistable behaviour. We further analyze the occurrence of normal mode splitting (NMS) due to mixing of the fluctuations of the cavity field and the fluctuations of the ion motion which indicates a coherent energy exchange. We also find that in the parameter regime where NMS exists, the steady state of the system shows continuous variable entanglement. Such a two-mode optomechanical system can be used for the realization of continuous variable quantum information interfaces and networks.

Normal-mode splitting and output-field squeezing in a Kerr-down conversion optomechanical system

An investigation is reported of the effects of a Kerr-down conversion nonlinear crystal inside an intrinsically nonlinear optomechanical cavity on the dynamics of the oscillating mirror, the intensity and the squeezing spectra of the transmitted field. We show that in comparison with a bare optomechanical cavity, the combination of the cavity energy shift due to the weak Kerr nonlinearity and increase in the intracavity photon number due to the nonlinear gain medium can increase the normal mode splitting in the displacement spectrum of the oscillating mirror. Our study demonstrates that at high temperatures, when the thermal fluctuations in the system are important, the optomechanical and nonlinearity-induced resonances are distinguishable in the output field spectrum. However, at low temperatures, the presence of both nonlinearities enhances the amplitude of the mechanical-mode contribution to the spectrum and leads to the occurrence of normal-mode splitting in the transmitted field spectrum even for low values of the input power. Also, at low temperatures, the Kerr-down conversion nonlinearity increases the radiation pressure contribution to the degree of squeezing of the transmitted field more than that of a bare optomechanical cavity or a nonlinear cavity (in the absence of optomechanical coupling). Furthermore, we find that for the blue-detuned laser the Kerr nonlinearity extends the domain of the stability of the system and leads to the normal-mode splitting of the movable mirror and noise reduction in the range of frequencies in which a bare cavity is not stable.

Normal mode splitting in hybrid BEC-optomechanical system

We consider an opto-mechanical cavity system consisting of Bose-Einstein condensate (BEC), trapped inside the optical cavity and driven by single mode laser field. The intracavity field acts as nonlinear spring which couples the condensate mode with moving end mirror of the cavity. We study the occurrence of normal mode splitting in the position spectra of the mechanical oscillator and condensate mode as a consequence of hybridization of the fluctuations of intracavity field, mechanical mode and condensate mode. We also discuss the modification in the dynamics of the mechanical oscillator due to frequency of the collective oscillations of cold atoms and the back action of the atoms on the mechanical mirror. Moreover, we investigate the normal mode splitting in the transmission spectrum of cavity field.

Quantum dynamics of two-optical modes and a single mechanical mode optomechanical system: Selective energy exchange

We study the quantum dynamics of an optomechanical setup comprising two optical modes and one mechanical mode. We show that the same system can undergo a dynamical phase transition analogous to Dicke–Hepp–Lieb superradiant type phase transition. We found that the coupling between the momentum quadratures of the two optical fields gives rise to a new dynamical critical point. We show that selective energy exchange between any two modes is possible by coherent control of the coupling parameters. In addition we also demonstrate the occurrence of normal mode splitting (NMS) in the mechanical displacement spectrum.

Optomechanically dark state in hybrid BEC–optomechanical systems

We study theoretically the propagation of slow light in a hybrid BEC–optomechanical system comprising a Bose–Einstein condensate (BEC) trapped inside an optical cavity with a moving end mirror. We show that when the system is driven by a weak probe in the presence of a strong laser field, there exists an analog of the electromagnetically induced transparency (EIT) in coupled BEC–optomechanical systems. When the coupling of the cavity field with a mechanical mirror and the condensate mode is considered simultaneously, three absorption peaks appear in the output spectrum of the probe field. The central absorption peak appears in the reflection spectrum of the weak probe field when the pump-probe detuning occurs at half the sum of frequencies of the two oscillators, which corresponds to the long-live dark state. Furthermore, we also study the occurrence of normal mode splitting in the output spectrum of the probe and Stokes fields.

Cavity optomechanics with a Bose–Einstein condensate: normal mode splitting

We study the normal mode splitting in a system consisting of a Bose–Einstein condensates (BECs) trapped inside a Fabry–Pérot cavity driven by a single mode laser field. We analyze the variations in frequency and damping rate of the collective density excitation of a BEC imparted by the optical field. We study the occurrence of normal mode splitting which appears as consequences of the hybridization of the fluctuations of the intracavity field and the condensate mode. It is shown that normal mode splitting vanishes for weak coupling between the condensate mode and the intracavity field. Moreover, we investigate the normal mode splitting in the transmission spectrum of the cavity field.

Quantum noise reduction using a cavity with a Bose–Einstein condensate

We study an opto-mechanical system in which the collective density excitations (Bogoliubov modes) of a Bose–Einstein condensate (BEC) is coupled to a cavity field. We show that the optical force changes the frequency and the damping constant of the collective density excitations of the BEC. We further analyse the occurrence of normal mode splitting (NMS) due to mixing of the fluctuations of the cavity field and the fluctuations of the condensate with finite atomic two-body interaction. The NMS is found to vanish for small values of the two-body interaction. We further show that the density excitations of the condensate can be used to squeeze the output quantum fluctuations of the light beam. This system may serve as an opto-mechanical control of quantum fluctuations using a BEC.