arXiv subjects

Ka-di Zhu

Publications and source records attributed to Ka-di Zhu.

5 recordsLinked to original sources

arXiv2026

Probing Axion Nucleon Coupling with Optomechanical Frequency Shift Measurements

The search for non-baryonic dark matter remains a key focus in modern physics, with the light pseudoscalar axion serving as a well-motivated candidate. Here, we present a laboratory-scale detection scheme to constrain axion-nucleon interactions using a levitated optomechanical sensor, complementing conventional spin-precession and inverse-square-law tests. By monitoring a micro-spherical test mass levitated near alternative aluminum and silver substrate mirrors, our dual-channel differential readout extracts the spin-independent force gradient generated by two-axion exchange. This approach translates the short-range interaction directly into a resolvable splitting in the optical transmission peaks. Our evaluation indicates that for symmetric nucleon coupling , the dual-cavity platform establishes competitive upper bounds, improving upon existing constraints by up to two orders of magnitude within the $m_{a}$ in [0.1, 1]eV mass range.

hep-ph↗

arXiv2024

Constraining symmetron fields with a levitated optomechanical system

The symmetron, one of the light scalar fields introduced by dark energy theories, is thought to modify the gravitational force when it couples to matter. However, detecting the symmetron field is challenging due to its screening behavior in the high-density environment of traditional measurements. In this paper, we propose a scheme to set constraints on the parameters of the symmetron with a levitated optomechanical system, in which a nanosphere serves as a testing mass coupled to an optical cavity. By measuring the frequency shift of the probe transmission spectrum, we can establish constraints for our scheme by calculating the symmetron-induced influence. These refined constraints improve by 1 to 3 orders of magnitude compared to current force-based detection methods, which offer new opportunities for the dark energy detection.

gr-qc↗

arXiv2021

Proposal for constraining non-Newtonian gravity at nm range via criticality enhanced measurement of resonance frequency shift

We propose a quantum mechanical method of constraining non-Newtonian gravity at the nanometer range. In this method, a hybrid electro-optomechanical system is employed. Applying a strong driving field, we can obtain normal mode splitting of the electromechanical subsystem which is related to the resonance frequency of the mechanical oscillator. Moreover, we investigate the relationship between the variance of normal mode splitting and the resonance frequency shift induced by the gradient of exotic forces provided that our system is operated at critical points. Furthermore, via suppressing the Casimir background, we set a constraint on the non-Newtonian gravity which improves the previous bounds by about a factor of 7 at 1 nanometer range. Our results indicate that our method could be put into consideration in relevant experimental searches.

quant-ph↗

arXiv2021

Proposal for measuring Newtonian constant of gravitation at an exceptional point in an optomechanical system

We develop a quantum mechanical method of measuring the Newtonian constant of gravitation, G. In this method, an optomechanical system consisting of two cavities and two membrane resonators is used. The added source mass would induce the shifts of the eigenfrequencies of the supermodes. Via detecting the shifts, we can perform our measurement of G. Furthermore, our system can features exceptional point (EP) which are branch point singularities of the spectrum and eigenfunctions. In the paper, we demonstrate that operating the system at EP can enhance our measurement of G. In addition, we derive the relationship between EP enlarged eigenfrequency shift and the Newtonian constant. This work provides a way to engineer EP-assisted optomechanical devices for applications in the field of precision measurement of G

quant-ph↗

arXiv2008

Slow Light in Artificial Hybrid Molecules

The optical properties of hybrid molecules composed of semiconductor and metal nanoparticles with a weak probe in a strong pump field are investigated theoretically. Excitons in such a hybrid molecule demonstrate novel optical properties due to the coupling between exciton and plasmon. It is shown that a non-absorption hole induced by coherent population oscillation appears at the absorption spectrum of the probe field and there exists slow light effect resulting in the great change of the refractive index. The numerical results indicate that with the different center-to-center distance between the two nanopaticles the slow light effects are greatly modified in terms of exciton-plasmon couplings.

cond-mat.mes-hall↗