Research On Phonon Blockade And Ground State Cooling In Micro System With Nanomechanical Resonator

Microsensors have attracted more and more attention in the fields of precision measurement and biomedicine due to their high precision,high sensitivity,reduced risk and other characteristics.The parameters that can be measured include velocity,pressure,touch,flow,magnetic field,temperature,ion concentration,biological concentration and so on.Nanomechanical system is a nano-scale mechanical system,which usually has excellent properties such as ultra-high quality factor,extremely high vibration frequency,small volume,admirable sensitivity,etc.Microsensors based on nanomechanical systems can be used in biomedical detection and other applications due to some significant advantages in the system.Nanomechanical resonator(NAMR)is a very representative nanomechanical system.It has all the advantages of nanomechanical system,including small mass,small size and high vibration frequency.In addition,it also has many advantages of macromechanical resonator.For instance,it still satisfies the conservation laws of energy and momentum,etc.Besides,these coupled systems,nanomechanical resonator coupled with other small quantum systems(such as qubits,etc.),can also be used to investigate some specific quantum effects and fundamental quantum principles.Particularly,a nanomechanical resonator coupled with an optical cavity can make up a cavity optomechanical system,which is popular in research currently.Microsensors based on nanomechanical resonators will be increasingly used in biomedical and other fields,on account of the investigation of dynamic characteristics in new microsystems which comprise nanomechanical resonator and other quantum systems.It will help to expand these applications in biomedical field.With the wide application of nanomechanical resonator,quantum optics will continue to penetrate into biology,medicine and other disciplines in the future.In this paper,phonon blockade and ground state cooling of nanomechanical resonator in coupling system are investigated.The details are as follows:The phenomenon of phonon blockade in a system which a qubit coupled with a nanomechanical resonator is studied.It is found that strong phonon antibunching occurs when all eigenvalues of non-Hermite Hamiltonian are equal to zero under weak driving.Therefore,we propose a zero eigenvalue approach to induce phonon blockade.In this paper,the influence of this method on phonon blockade is analyzed in detail,the best conditions are given and the physical mechanism is explained.Moreover,unlike conventional phonon blockade and unconventional phonon blockade,whether strong nonlinearity or weak nonlinearity,the antibunching effect of phonons can be realized.The conclusion provides a method for realizing a single phonon source,which will have important significance and application prospects in the research fields of quantum information processing and precision measurement.Based on the double-cavity coupling system,a dynamic dissipative synchronous cooling scheme is proposed under the condition of strong coupling region and resolved sideband.By employing the cavity dissipation as useful resources and using the coupling channel between the two cavities,the heating effects are strongly suppressed through dynamic modulation of the cavity dissipation.Thus the cooling process is greatly accelerated and the cooling limit is significantly reduced,so as to make nanomechanical resonators cool synchronously and rapidly to the ground state.In addition,we analyze the dynamics of cavity optomechanical cooling using non-perturbative method,and present the analytical results for the cooling dynamics and cooling limits.This conclusion is helpful for the study of multiple-mode ground state cooling using active control.