The composite micro-nano multi-mode system realizes the conversion of fast light to slow light phenomenon

Professor Chen Huajun’s team from the School of Mechanics and Optoelectronic Physics of Anhui University of Science and Technology theoretically proposed a multi-mode coupled composite nanooscillator system by introducing more acoustic modes in typical semiconductor quantum dot-nanomechanical oscillator hybrid quantum systems. Through the study of coherent optical phenomena of the system, the effective regulation of the group velocity is realized, which provides a promising integrated platform for quantum information processing at the chip scale. The relevant research results were recently published in “Optics and Laser Technology”.

Multi-mode nanomechanical oscillator coupling model diagram Courtesy of Anhui University of Science and Technology

Composite quantum systems couple disparate physical components together to achieve novel properties that individual elements cannot have, which has attracted great attention to the study of quantum phenomena in this system and the development of quantum technology. Binary coupled composite systems, such as solid-state two-level systems (superconducting bits, semiconductor quantum dots, semiconductor defects, atomic systems, nitrogen vacancy defect (NV) centers, etc.) coupled with nanomechanical oscillators (such as semiconductor nanowire oscillators, cantilever oscillators, carbon nanotube oscillators, layered two-dimensional graphene or molybdenum disulfide oscillators) are the most typical composite quantum systems.

“In order to achieve the integration of nanomechanical oscillators on a chip, more acoustic modes need to be introduced into a typical binary coupling system, and the coupling of multiple modes will produce richer optical features that are different from binary coupled systems. The coupling of the two-level system with the acoustic mode can be achieved by different coupling mechanisms, such as the coupling of the two-level system and the acoustic mode can be achieved by the coupling of material tension modulation and the magnetic interaction, and the coupling between the acoustic modes can be achieved by the Coulomb interaction and the gate voltage applied to the acoustic mode. Chen Huajun introduced to China Science News.

Through the study of the optical characteristics of multi-mode composite nanooscillators, the system will provide a carrier and medium for light field regulation on the one hand, and provide a theoretical basis for quantum information processing with photons as the carrier. On the other hand, the study of multivariate composite systems will also expand the basic physics theory, and provide a theoretical model and theoretical basis for exploring the interaction law in multivariate systems and revealing their dynamic mechanisms.

By compiling different nanomechanical oscillators, Chen Huajun’s team can realize a series coupled parallel coupled nanomechanical oscillator network system, and its optical absorption spectrum can show double-Fano resonance and triple-Fano resonance. Fano resonance is an effective means of controlling the propagation of light pulses. It is found that different coupling systems can be realized by controlling different coupling mechanisms, and the regulation of multi-Fano resonance can be realized, and then the conversion of group speed from fast light to slow light (or slow light to fast light) can be obtained.

“Although our study uses semiconductor nanomechanical oscillators clamped at both ends as an example, this multi-acoustic mode coupling system can also be extended to other systems, such as coupled carbon nanotube oscillators coupled to an NV center, where spin-phonon interactions can be achieved by material tension or magnetic coupling, and couplings between carbon nanotubes can be obtained by phonon exchange interactions.” This is because NV spins have a long coherence time even at room temperature. Chen Huajun said.

When the multi-acoustic mode coupled nanomechanical oscillator system is realized, it is inevitable that the prepared nanomechanical oscillator will have different quality, quality factor, and resonance frequency when manufacturing nanomechanical oscillator. On the basis of the previous work, the research group further studied the different optical transmission characteristics induced by each nanomechanical oscillator. The multi-mechanical mode coupling system builds a bridge between the fields of optics and mechanics, and provides a good integrated platform for the application of quantum information processing at the chip level.

The reviewer said: “The composite nanosystem coupled with multiple acoustic modes proposed by the author through mode coupling theory can realize the conversion of different optical phenomena, and then realize the quantum regulation of light transmission, which is of great significance in quantum information processing.” (Source: Wang Min, China Science News)

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