The Ultrasensitive Detections Of Dark Energy And Dark Matter With Condensed Matter Optomechanical System And Its Application In Surface Science

Optomechanics is a frontier interdiscipline which combines the optical micro cavity and the macroscopical mechanics.The mechanical resonator coupled with an optical cavity by the radiation pressure can serve as nano-optomechanical system,which is a hot research topic recently.Today,the scale of the mechanical resonator can reach micro and nano meters along with the development of the nanotechnology and nanofabrication.Recently,the couplings between the plasmon cavity and the molecular resonators are also very attractive.Usually,the nanomechanical resonator has low damping,high vibration frequency,small mass,and other excellent characteristics.Due to these advantages,nanomechanical system is widely employed in force detection and mass measurement.In contrast to micro-fabricated devices,optically trapped nanoparticles in vacuum do not suffer from clamping losses,hence leading to much larger Q-factors and narrower bandwidth without other main decoherence sources of the mechanical resonator,which provides the new platform for the ultrasensitive detection of the dark energy and dark matter.In this thesis,we present all-optical means for detecting novel physical phenomenon based on the pump-probe technique,including some weak forces induced by dark matter and dark energy.The sensitivity can be enhanced remarkably compared with previous experimental and theory works.We also investigate the quantum coupling in the plasmon-molecules system.The research findings are very enlightening,especially in terms of van der Waals optical switch,atom-resolution mass sensor and ultralow frequency band Raman mode detection.The whole thesis includes the following nine chapters.The first chapter is the introduction,where the basic concept of nano-optomechanical system and its current developments is introduced.We also introduce the basic information about optical levitation,and briefly describe the manufacture methods and their various applications.Then we introduce the molecular cavity optomechanics as a theory of plasmon-enhanced Raman scattering.In Chapter Two,we provide a scheme to probe the gradient of gravity at nanoscale in a levitated nanomechanical resonator coupled to a cavity via two optical fields’control.The enhanced sharp peak on the probe spectrum will suffer a distinct shift with the non-uniform force being taken into consideration.The nonlinear optics with very narrow bandwidth 10^-8Hz resulted from the extremely high quality factor will lead to a super resolution of 10^-20N/m for the measurement of gravity gradient.The improved sensitivity may offer new opportunities for detecting Yukawa moduli forces and Kaluza-Klein gravitons lived in extra dimensions.Particles with electric charge 10^-14e in bulk mass are not excluded by present experiments.In the Chapter Three we provide a feasible scheme to measure the millicharged particles via the optical cavity coupled to a levitated nanosphere.The results show that the optical probe spectrum of the nano-oscillator presents a tiny shift due to the existence of millicharged particles.Compare to the previous experiment the sensitivity can be improved by the using of a specific geometry to generate an electric field gradient and a pump-probe scheme to read the weak frequency shift.Owing to the very narrow linewidth(10^-6Hz)of the optical Kerr peak on the spectrum,this shift will be more obvious,which makes the millicharges more easy to be detectable.The technique proposed here paves the way for new applications for probing dark matter and nonzero charged neutrino in the condensed matter.The chameleon scalar field is a matter-coupled dark energy candidate with the screening mechanisms.In the Chapter Four,we propose two different quantum optomechanical schemes to detect the possible signature of chameleons via the optical levitation and pump-probe spectroscopy.Compare to the previous experiment the sensitivity can be improved by the using of electrostatic shield and a pump-probe scheme to read the weak frequency splitting or frequency shift.Considering the noise limit,the constraint is about 2-3 orders of magnitude stronger than the ones from atom interferometry under the ultralow pressure.We expect that this work will be a useful addition to the current literature on proposals to detect effects of dark energy.Many experiments have been conducted to detect hypothetical large extra dimensions from sub-millimeter to solar system separations.However,direct evidence for such extra dimensions has not been found.In Chapter Five we present a scheme to test the gravitational law in 4+2dimensions at micron separations by optomechanical methods.We demonstrate the feasibility of the normal mode splitting in the optomechanical system under the gravitational interaction between two levitated resonators.The weak frequency splitting can be optically read by the optical pump-probe scheme.The sensitivity can be improved by suppressing the effect of the Casimir force coupling and the electrostatic interaction.Thus,we can detect the large extra dimensions at low noise levels based on the levitation optomechanics without the isoelectronic technique.Different from the traditional force-distance measurement,due to a resonant frequency shift or a peak splitting on probe spectrum,we have proposed a convenient method to measure the van der Waals force strength and interaction energy via nonlinear spectroscopy in the Chapter Six.Cavity optomechanics is applied to study the coupling behavior of the interacting molecules in surface plasmon systems driven by two color laser beams.The minimum force value can reach approximately 10^-15N,which is 3-4 orders of magnitude smaller than the widely applied Atomic Force Microscope（AFM）.It is also shown that two adjacent molecules with similar chemical structures and nearly equal vibrational frequencies can be distinguished easily by the splitting of the transparency peak.Based on this coupled optomechanical system,we also conceptually design a tunable optical switch by van der Waals interaction.Our results will provide new approaches for the understanding of the complex and dynamic interactions in molecule-plasmon systems.In Chapter seven,we propose an ultralow frequency Raman mode detection scheme and a room temperature optical mass spectrometer with the sensitivity down to single atom through the coupling between surface plasmon and suspended graphene nanoribbon resonator.The mass is determined via the vibrational frequency shift on the probe absorption spectrum while the atom attaches to the nanoribbon surface.We provide methods to separate out the signals of the ultralow frequency vibrational modes from strong Rayleigh background firstly based on the quantum coupling with pump-probe scheme.Owing to the spectral enhancement in the surface plasmon and the ultralow mass of the nanoribbon,this scheme results in a narrow linewidth（GHz）and ultrahigh mass sensitivity（30yg）.Benefited from the low noises,our optical mass sensor can be achieved at room temperature and reach ultrahigh time resolution.Chapter Eight introduces a"short-term measurement"scheme in order to eliminate the mechanical damping induced by the laser cooling.The center-of-mass motion of a nanoparticle trapped in vacuum can experience extremely low dissipation resulting in robust decoupling from the heat bath.Thus the ground state measurement can be completed in a short sample time after the optomechanical cooling was finalized,which leads to MeV mass sensitivity.The highly sensitive mass sensor proposed here may eventually be able to realize the direct probing for rest mass of atom and molecules.In Chapter Nine,it is the main conclusions and the prospect.