Two-mode Resonator Research Articles

Phonon-induced interactions and entanglement formation between two microcavity modes mediated by two semiconductor quantum dots

Using a polaron master equation approach, we investigate the cooperative two-photon resonance behavior between two modes of a field inside a semiconductor microcavity containing two quantum dots. The cooperative two-mode two-photon resonance occurs when two off-resonant quantum dots, initially prepared in exciton states, emit one photon in each cavity mode and deexcite simultaneously. Using this two-photon two-mode interaction, we demonstrate how to generate an entangled state of two qutrits (tripartite unit of quantum information). The bases for the qutrits are formed by the states of the cavity modes containing zero, one, and two photons. We also study the effect of exciton-phonon coupling on the entanglement and the probability of generating two-qutrit states, and explore the role of the phonon bath temperature.

A Design of Low Profile Microstrip Patch Antenna With Bandwidth Enhancement

It is known that for a microstrip antenna (patch antenna) resonant in a single mode, if the height of the antenna is strictly limited, the bandwidth is narrow, and the performance at the side frequencies is worse than that at the centre frequency. A way to solve this problem is to combine two modes into one single narrow band. However, almost all the two-mode resonance methods reported are for wideband patch antennas because the frequency ratio of two bands is commonly large and hard to decrease. In this article, a detailed mode analysis based on transmission line theory is performed, and a mode shift theory is established for patch antennas. A dual-mode patch antenna with any frequency ratio can be designed. Guided by this theory, a low-profile patch antenna with a size of only $0.23\lambda _{0}\times 0.23\lambda _{0}\times 0.027\lambda _{0}$ ( $\lambda _{0}$ is the wavelength of the centre frequency in free space) for the Beidou BD3 band (1.258 GHz-1.278 GHz) is designed. The antenna resonates in two modes, and the frequency ratio is only 1.02. The simulated and measured results show that the gain performance of the proposed antenna is almost flat over the operating band (3 dBic-3.1 dBic), which is hard to achieve through any other bandwidth enhancement method.

Plasmon-Induced Transparency and High-Performance Slow Light in a Plasmonic Single-Mode and Two-Mode Resonators Coupled System

We investigate the plasmon-induced transparency (PIT) and slow-light properties in a plasmonic single-mode and two-mode resonators coupled system. The bare-state PIT effect originates from the destructive interference between a radiant standing-wave mode in the slot cavity and two subradiant travelling-wave modes in the ring resonator. A theoretical model is established to describe this PIT system, and the analytical results agree well with the numerical simulations. The difference between our structure and similar coupled resonators structures is shown. The transparency window can be tuned by adjusting the structural parameters, and two types of PIT lineshape are discussed in detail. The numerical results reveal that the PIT window with weakly resolved and equal doublet peaks exhibits high-performance slow light. A delay-bandwidth product larger than 1 and ultralow dispersion are obtained, and a delay of 1 bit with negligible pulse distortion is achieved in the proposed system.

One-Photon Scattering by N-Atom System: Application to One- and Two-Mode Resonator

The system of N identical two-level atoms coupled with a quantized electromagnetic field prepared via a one-photon Fock state is investigated. The corresponding N-particle state amplitudes in one- and two-mode resonators are calculated for several space configurations in the cases of closed conservative and open dissipative systems. The nature and the structure of the Weisskopf–Wigner approximation is revealed in the many-body problem. It is shown that the space distribution of atoms, the total number of atoms, and even the available volume for the field modes define the behavior of system’s state amplitudes in time. The elaborated theory allows one to analytically describe the time evolution of the system for a quite wide range of the space configurations, if the specific “cyclic” restrictions are applied.

One-photon scattering by an atomic chain in a two-mode resonator: cyclic conditions.

In this work, a chain of N identical two-level atoms coupled with a quantized electromagnetic field, initially prepared via a single-photon Fock state, is investigated. The N-particle state amplitude of the system is calculated for several space configurations of the atoms in the Weisskopf-Wigner approximation. It was shown that the space configuration of an atomic chain, the total number of atoms, and even the available volume for the field modes define the behavior of the system state amplitude with time. Applying the condition of ‘cyclic bonds’, presented in this work, to the elaborated theory allows to describe the system time evolution, practically, for any space configuration.

One-Photon Scattering by an Atomic Chain in One- and Two-Mode Resonators

A chain of N identical two-level atoms coupled with the electromagnetic field, prepared via a single-photon Fock state, is investigated. It is found that, if the interaction between atoms is negligible, than the obtained dynamic equations for the probability amplitudes allow, in a certain sense, an interpretation of the dynamics of states in the classical fashion in terms of a superposition of oscillatory modes of the system under study. The derived equations reveal how a space configuration of the system of atoms affects the dynamics of the atomic states, particularly the “decay” rates of separate atoms and the system as the whole.

Entangled light via nonlinear vacuum-multiparticle interactions

We investigate the generation of a strongly entangled electromagnetic field through laser pumping a collection of N two-level atoms in a two-mode optical resonator. The vacuum-multiparticle interactions enhance the coupling of the atomic sample to the cavity modes facilitating the creation of entangled photons at higher frequencies. In the dispersive atom-cavity limit, one can obtain a steady-state output field consisting of tens of such photons per mode.

Collective radiation of a system of two three-level V-type atoms in a two-mode resonator with losses

Collective spontaneous radiation of a system of two three-level V-type atoms interacting with two modes of a quantum electromagnetic field in a resonator with finite Q-factor is investigated based on the control kinetic equation for the density matrix. Time dependences of the average number of photons and radiation intensity of each mode are derived for the case in which atoms at the initial moment of time are in different excited states.

Evidence for Low‐dimensional Chaos in Semiregular Variable Stars

An analysis of the photometric observations of the light curves of the five large amplitude, irregularly pulsating stars R UMi, RS Cyg, V CVn, UX Dra and SX Her is presented. First, multi-periodicity is eliminated for these pulsations, i.e. they are not caused by the excitation of a small number of pulsation modes with constant amplitudes. Next, on the basis of energetics we also eliminate stochasticity as a cause, leaving low dimensional chaos as the only alternative. We then use a global flow reconstruction technique in an attempt to extract quantitative information from the light curves, and to uncover common physical features in this class of irregular variable stars that straddle the RV Tau to the Mira variables. Evidence is presented that the pulsational behavior of R UMi, RS Cyg, V CVn and UX Dra takes place in a 4-dimensional dynamical phase space, suggesting that two vibrational modes are involved in the pulsation. A linear stability analysis of the fixed points of the maps further indicates the existence of a two-mode resonance, similar to the one we had uncovered earlier in R Sct: The irregular pulsations are the result of a continual energy exchange between two strongly nonadiabatic modes, a lower frequency pulsation mode and an overtone that are in a close 2:1 resonance. The evidence is particularly convincing for R UMi, RS Cyg and V CVn, but much weaker for UX Dra. In contrast, the pulsations of SX Her appear to be more complex and may require a 6D space.

Generation of a class of arbitrary two-mode field states in a cavity.

We have shown how a class of arbitrary two-mode field states can be generated by the injection of three-level \ensuremath{\Lambda}-type atoms into a two-mode resonator. An explicit example with SU(2) coherent states has been worked out.

A two-mode waveguide-dielectric resonator with beyond-cutoff couplings

A two-mode waveguide-dielectric resonator with beyond-cutoff couplings