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The Japan Society of Applied Physics

Quantum States in Nonlinear Coupler with Frequency Mismatch

Mansoor Zahirzai, Rafael Julius, Abdel-Baset M.A. Ibrahim, Hichem Eleuch, P. K. Choudhury

Published Sep 18, 2019• 0 citations
OpenAlex

Abstract

The effects of squeezing have been of great importance in quantum computing [1], as evidenced in the studies of squeezed light presented in the literature [2]. The present work discusses on the possibility of enhancing squeezing using nonlinear coupler utilizing different operating frequencies of the input modes. In our two-channel model, one of the channels contains the fundamental mode, whereas the other one confines the next two higher-order modes. Here we examine numerically the effect of frequency mismatch on the dynamics of the generated squeezed light.

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The effects of squeezing have been of great importance in quantum computing [1], as evidenced in the studies of squeezed light presented in the literature [2]. The present work discusses on the possibility of enhancing squeezing using nonlinear coupler utilizing different operating frequencies of the input modes. In our two-channel model, one of the channels contains the fundamental mode, whereas the other one confines the next two higher-order modes. Here we examine numerically the effect of frequency mismatch on the dynamics of the generated squeezed light.
Abstract Squeezed states of light in a three-channel nonlinear coupler with second-order nonlinearity using the phase space method and the analytical perturbative method is reported in this paper. The system is studied under the frequency mismatch condition, where the frequencies of the pump mode are not common. The effect of frequency mismatch on the generated squeezed states is investigated. We have found that the frequency mismatch does significantly affect the behavior of the generated squeezed states only at higher values of linear coupling between the waveguides. By increasing the frequency mismatch, the squeezing pattern also evolves from a collapses-revivals-like squeezing into a constant oscillation.
The properties of squeezing, in relation to the different interaction frequencies of the input modes in three-mode Kerr nonlinear coupler consisting of two linearly-coupled Kerr waveguides, were explored. Utilizing the exact representation of a set of noisy-stochastic equations, an investigation was made of the first-order properties of squeezing for two- and three-mode interactions with frequency mismatch. It was observed that enhanced squeezing could be obtained under certain conditions of interactions.
Abstract In this work, we examine the quantum features of a multi-waveguide nonlinear coupler exploiting the second-and third-order nonlinearities. The considered system contains four identical channels, each with a single fundamental transverse mode. The essence of this type of nonlinear coupler is to examine the effect of two or more competing nonlinearities on the generated nonclassical features in this class of devices. Here, we consider the case of second harmonic generation, wherein the fundamental harmonic (FH) fields are up-converted in pairs to double-frequency second harmonic (SH) fields, which are then evanescently coupled with the fields from other Kerr nonlinear waveguides. Using the positive P representation of the phase space, the time-evolution of the density matrix could be mapped to the corresponding Fokker–Planck equation of a classical quasiprobability distribution. Using Langevin stochastic equation, an exact representation of the system in phase space led to the demonstration of sub-Poissonian property, squeezing, and entanglement. With more effective squeezing achieved in all channel waveguides, the present system with χ(2)–χ(3) interaction can be a more efficient alternative to other versions of nonlinear couplers such as the quantum optical dimer (QOD) and Kerr nonlinear coupler (KNC). Furthermore, such a structure offers more flexibility in coupled-mode interactions in the form of correlation between the modes in different waveguides. This provides a better mechanism for the generation of enhanced nonclassical effects.
We report an examination on the possibility of generating enhanced squeezed light over two octaves of frequency difference, with each octave incorporating two-channel nonlinear waveguides suited for the fundamental, second, and fourth harmonic modes. We investigate the behavior of squeezing owing to the presence of evanescent coupling in scenarios for traveling-wave and intracavity cases. We show that the existing technique may generate enhanced squeezing in a frequency range spanning the fourth harmonic.
We investigate nonlinear couplers whose operation is based on Raman or Brillouin scattering. A quantum approach is used. Strong coherent laser pumping is assumed and linearized Heisenberg-Langevin equations of motion are solved. The influence of linear coupling constants, losses and phase mismatches on the dynamical behaviour of the coupler is discussed. Quantum statistical properties of optical modes involved in the interaction are investigated within the framework of the generalized superposition of coherent signal and quantum noise. Most attention is devoted to the possibility of generation of non-classical light. It is shown that such light can be generated only in compound modes according to our model and influence of various parameters on the generation is discussed. Optimal conditions for the generation of squeezed light are found.
We investigate both codirectional and contradirectional nonlinear couplers composed of two nonlinear waveguides operating by second-harmonic generation. We take into account possible mismatches inside the waveguides and between them. We calculate the photon number distribution, its factorial moments, quadrature and integrated intensity variances and quadrature uncertainty product taking into account the effects of transmission of light between waveguides. Incident beams are assumed to be coherent, squeezed and mixed with external noise. Second-harmonic modes are assumed to be pumped with strong coherent beams. We show that non-classical behaviour of beams generated by the nonlinear waveguides can be transferred between them and controlled by linear and nonlinear mismatches. In the contradirectional regime of propagation, asymptotic non-classical states can be generated.