The cavity, the mechanical resonator, and the two-level emitter make up the hybrid system, which has garnered significant interest due to its composition. For instance, the mechanical resonator can couple to the cavity via the action of radiation pressure and can couple to the two-level emitter by Casimir force.
Comprehensive investigations have been conducted on the hybrid system consisting of a cavity and a two-level emitter. It can be utilized to examine various fascinating optical features, such as the electromagnetically generated transparency, the ground-state cooling of a mechanical resonator, and the Kerr effect.
What is the Kerr Effect?
A material's refractive index changes in reaction to an applied electric field. This phenomenon is known as the Kerr effect.
In contrast to the Pockels effect, which varies linearly with the electric field, the induced index change in the Kerr effect is directly proportional to the square of the electric field. All substances exhibit the Kerr effect; however certain liquids exhibit it more prominently than others.
Kerr Electro-Optic Effect and Optical Kerr Effect
There are two cases of the Kerr effect, the DC Kerr effect, also known as the Kerr electro-optic effect, and the optical Kerr effect or AC Kerr effect.
The Kerr electro-optic effect is a specific example in which an external electric field that is slowly changing is delivered to a sample material, such as by applying a voltage across electrodes. This makes the sample birefringent, with distinct refraction indices for light that is polarized either perpendicular or parallel to the applied field.
The optical Kerr effect occurs when light causes an electric field. This generates a change in the refractive index proportionate to light intensity. This refractive index change causes self-focusing, self-phase modulation, and modulational instability and is the foundation for Kerr-lens mode-locking.
This phenomenon only occurs with laser beams. The optical Kerr effect dynamically changes the mode-coupling characteristics in multimode fiber, which might be used in all-optical switching mechanisms, nanophotonic systems, and low-dimensional photo-sensors.
Recent Developments that Lead to Research for this Study
Graphene resonators have potential application in mass sensing and force detection due to their high-quality factor, high frequency and low mass density properties.
A method was developed for measuring the coupling coefficients between nano-mechanical resonators and quantum dots. Quantum level compression and a measurement method of vibrating graphene mechanical resonator via two-level emitter has also been developed.
The optical Kerr effect revealed signatures of quantum dynamics with potential applications in feedback control and adaptive measurement. It is tuned by controlling frequency pump light in the optomechanical system based on two-layer graphene. Moreover, quantum devices such as the Kerr modulator and the Kerr switch have been recently suggested.
These developments motivated the researchers of this study to propose a method for a hybrid system Kerr switch with the cavity, graphene resonator and two-level emitter.
Interesting Findings of the Research
In contrast to previous studies, this study demonstrates that the Kerr effect can be improved by elevating the coupling coefficient between the graphene resonator and the two-level emitter. Within the framework suggested by the study, the pump light also plays a critical part in the optical Kerr effect. The study provides a more straightforward method to measure graphene resonator frequency.
The study found that increasing the coupling strength of two-level emitter and graphene mechanical resonator increases the Kerr coefficient. However, when the coupling coefficient is increased between the two-level emitter and cavity, the Kerr coefficient becomes smaller and smaller.
The reason for this phenomenon is that new quantum interference effects and correlations are due to the interaction and competition between the various physical interactions.
The research suggested an optical Kerr switch based on a hybrid system of a two-level emitter, a cavity, and a mechanical resonator made of graphene. This Kerr switch is considerably modified by adjusting the intensity of the pump light. The frequency of the graphene resonator has been measured using a novel and accurate method. The Kerr effect is strengthened by raising the coupling coefficient between the graphene resonator and two-level emitter, according to a comparison of the effects of various types of coupling strength on the Kerr coefficient.
The current findings could serve as a roadmap for theoretical and practical research on hybrid quantum devices in the quantum information processing field.
Qinghong Liao, Min Xiao, Haiyan Qiu, (2022) Kerr effect based on two-level emitter coupled to graphene resonator and cavity. Optics Communications. https://www.sciencedirect.com/science/article/pii/S0030401822005144