Three-mode Resonator Research Articles

Quantum-Interference-Enhanced Phonon Laser in Cavity Optomechanics

Cavity-optomechanics-based phonon lasers are traditionally described in terms of three-mode resonance, while the energy nonconservation optomechanical terms are conventionally ignored. Here, we present a complete theory of phonon lasers, emphasizing the importance of the previously omitted optomechanical interaction. We show that this indispensable optomechanical interaction is equivalent to a Kerr nonlinear interaction. Analytical results show that the interference between this Kerr-type interaction and three-mode resonance adds a transition channel with no phonon emission or absorption, thus enhancing phonon lasing and realizing an ultralow-threshold phonon laser and even a phonon cooler. The interference effect produces an asymmetric gain profile with a Fano spectral shape in addition to the traditional Lorentzian shape. Our complete theory shows perfect agreement with existing experiments and provides a new degree of freedom to manipulate optomechanical phonon lasers.

Experimental study of retrieval efficiency of Duan-Lukin-Cirac-Zoller quantum memory by optical cavity-enhanced

<sec>Long-distance entanglement distribution is an important task for quantum communication, but difficult to achieve due to the loss of photons in optical fiber transmission. Quantum repeater is a scheme to solve this problem. In this scheme, the long distance of entanglement distribution is divided into several small parts, the entanglement is established first at both ends of each part, then, the entanglement distance is extended through the entanglement exchange of adjacent interval parts, in order to achieve the long distance entanglement distribution. Of them, the Duan-Lukin-Cirac-Zoller (DLCZ) protocol based on the cold atom ensemble and the linear optics which can generate and store entanglement, is regarded as one of the most potential schemes. In the process of DLCZ, retrieval efficiency is an important index of the quantum repeater, because it will influence each entanglement exchange operation between adjacent quantum repeater nodes. Generally, the retrieval efficiency is improved by optimizing the reading pulse, increasing the optical depth (OD) of the atomic ensemble and the cavity enhancement. The ring cavity constrains the light field to increase the intensity of the interaction between light and atoms, and effectively improve the retrieval efficiency of the quantum memory.</sec><sec>In this work, atomic ensembles are placed in a ring cavity. The cavity length is 3.3 m and the fineness is 13.5. The optical loss of all ring cavity is 21%, mainly including 15% loss of other optical elements and 6% loss of the cell. In order to increase the retrieval efficiency, we need to ensure the mode resonance of read-out photon, write-out photon and locking. The cavity needs two input beams of light: one comes from the path of read-out photon and the other from the path of write-out photon in the reverse direction. The two beams are locked at the same frequency as the write-out photon and the read-out photon respectively. The cavity length is adjusted by moving the cavity mirrors’ positions through translating the frame, to make two light modes resonate. The acousto-optic modulator (AOM) is inserted into the path of the locking to control the frequency of the locking. By adjusting the AOM to change the frequency of the locking, the locking can be coincident with the write-out and read-out cavity modes. Then, the three-mode resonance can be achieved</sec><sec>When the cavity mode resonates with the atomic line, it will lead the atomic formants to split. thereby affecting the enhancement effect of retrieval efficiency. In the experiment, the detuning of the read light will affect the frequency of the read-out photon, and further affect the detuning of the cavity mode with the resonance line of the atom. Thus, by increasing the detuning between the reading light and the atomic transition line, the frequency splitting between the two modes can be reduced, then enhance the retrieval efficiency. We study the relation between the enhancement factor of the retrieval efficiency and the detuning amount of the reading light relative to the atomic resonance line. The results show that when the detuning amount of reading light is 80 MHz, the intrinsic readout efficiency is 45%, and the readout efficiency is enhanced by 1.68 times.</sec>

Magnetoelastic axisymmetric multi-modal resonance and Hopf bifurcation of a rotating circular plate under aerodynamic load

In this article, an investigation of magnetoelastic axisymmetric multi-mode interaction and Hopf bifurcations of a circular plate rotating in air and uniform transverse magnetic fields is presented. The expressions of electromagnetic forces and an empirical aerodynamic model are applied in the derivation of the dynamical equations, through which a set of nonlinear differential equations for axisymmetric forced oscillation of the clamped circular plate are deduced. The method of multiple scales combined with the polar coordinate transformation is employed to solve the differential equations and achieve the phase–amplitude modulation equations for the interaction among the first three modes under primary resonance. Then, the frequency response equation for the single-mode vibration, the steady-state response equations for three-mode resonance and the corresponding Jacobian matrix are obtained by means of the modulation equations. Numerical examples are presented to show the dependence of amplitude solutions as a function of different parameters in the cases of single mode and three-mode response. Furthermore, a Hopf bifurcation can be found in three-mode equilibrium by choosing appropriate parameters, where a limit cycle occurs and then evolves into chaos after undergoing a series of period-doubling bifurcations.

Numerical investigation on oscillatory Turing patterns in a two-layer coupled reaction–diffusion system

In this paper, various kinds of spontaneous dynamic patterns are investigated based on a two-layer nonlinearly coupled Brusselator model. It is found that, when the Hopf mode or supercritical Turing mode respectively plays major role in the short or long wavelength mode layer, the dynamic patterns appear under the action of nonlinearly coupling interactions in the reaction–diffusion system. The stripe pattern can change its symmetrical structure and form other graphics when influenced by small perturbations sourced from other modes. If two supercritical Turing modes are nonlinearly coupled together, the transition from Turing instability to Hopf instability may appear in the short wavelength mode layer, and the twinkling-eye square pattern, traveling and rotating pattern will be obtained in the two subsystems. If Turing mode and subharmonic Turing mode satisfy the three-mode resonance relation, twinkling-eye patterns are generated, and oscillating spots are arranged as square lattice in the two-dimensional space. When the subharmonic Turing mode satisfies the spatio-temporal phase matching condition, the traveling patterns, including the rhombus, hexagon and square patterns are obtained, which presents different moving velocities. It is found that the wave intensity plays an important role in pattern formation and pattern selection.

Development of UWB HTS Bandpass Filters With Microstrip Stubs-Loaded Three-Mode Resonator

We developed ultra-wideband high-temperature superconducting bandpass filters for Japan's low-band spectrum. First, we designed a low-band filter with a microstrip three-mode resonator loaded with two open stubs. The three-mode resonator is characterized by the ease of controlling the frequency response compared with other resonators. In addition, we loaded a low-pass filter consisting of a microstrip coupled-line hairpin unit to suppress all unwanted high-frequency harmonics. The simulated filtering characteristics of the low-band filter showed a wide passband within 3.44-4.67 GHz with a minimum insertion loss of 0.06 dB. After that, we fabricated a low-band filter with YBCO thin films deposited on sapphire substrates. The frequency response of the fabricated filter was clearly observed at 70 K, and the measured response without any tuning matched well with the simulated one. The measured filtering characteristics showed a wide passband within 3.46-4.80 GHz with a minimum insertion loss of 0.01 dB. The box resonances of the copper housing were suppressed by introducing radar absorbent material under the top metal.

Non-linear modelling of beat Cepheids: resonant and non-resonant models

The phenomenon of double-periodic Cepheid pulsation is still poorly understood. Recently we rediscussed the problem of modelling the double-periodic pulsation with non-linear hydrocodes. We showed that the published non-resonant double-mode models are incorrect, because they exclude the negative buoyancy effects. Aims. We continue our efforts to verify whether the Kuhfuss one-equation convection model with negative buoyancy included can reproduce the double-periodic Cepheid pulsation. Methods. Using the direct time integration hydrocode, which implements the Kuhfuss convection model, we search for stable double-periodic Cepheid models. We search for models pulsating in both fundamental and first overtone modes (F+1O), as well as in the two lowest order overtones (1O+2O). In the latter case, we focus on reproducing double-overtone Cepheids of the Large Magellanic Cloud (LMC). Results. We have found full amplitude non-linear beat Cepheid models of both types, F+1O and 1O+2O. In the case of F+1O models, the beat pulsation is most likely caused by the three-mode resonance, 2omega_1=omega_0+omega_2, while in the double-overtone models the underlying mechanism (resonant or non-resonant) cannot be identified beyond doubt. Double-periodic models found in our survey exist, however, only in narrow period ranges and cannot explain the majority of the observed double-periodic objects. Conclusions. With only little doubt left, we conclude that current one dimensional one-equation convection models are incapable of reproducing the majority of the observed beat Cepheids. Among the shortcomings of current pulsation hydrocodes, the simple treatment of convection seems to be the most severe one. Growing evidence for the presence of non-radial modes in Cepheids suggests that the interaction between radial and non-radial modes should also be investigated.

Superlattice patterns in vertically oscillated rayleigh-Benard convection

We report the first observations of superlattices in thermal convection. The superlattices are selected by a four-mode resonance mechanism that is qualitatively different from the three-mode resonance responsible for complex-ordered patterns observed previously in other nonequilibrium systems. Numerical simulations quantitatively describe both the pattern structure and the stability boundaries of superlattices observed in laboratory experiments. In the presence of the inversion symmetry, superlattices are found numerically to bifurcate supercritically directly from conduction or from a striped base state.