Research On The Quantum Properties In Nanomechanical Resonator Coupling Systems

Quantum entanglement and squeezing are the basic concepts of quantum optics and the basic characteristics of quantum dynamics.They have important applications in the fields of quantum computing,quantum transmission and quantum communication.Nanomechanical resonators such as carbon nanotubes and graphene have the advantages of small size,low loss,high quality factor and high vibration frequency.They have important applications in high-precision measurement,quantum sensing and quantum computing.The all-optical measurement method with high sensitivity and accuracy provides a new way for the high-precision measurement of physical quantities based on the coupled nanomechanical resonator system.The diamond nitrogen vacancy center(NV center)has unique advantages such as long coherence,good maneuverability,and easier readability,which is an excellent carrier for realizing quantum computing and quantum sensing.Based on the nanomechanical resonator coupling system,the dynamical characteristics of quantum entanglement,quadrature squeezing,electromagnetically induced transparency,and quantum sensing are investigated in this paper.The specific research content is as follows:The quantum entanglement and quadrature squeezing properties of the system based on graphene membrane coupling atom and cavity field under the dressed states are studied.By adjusting the atomic coherent angle,the evolution characteristics of entanglement and quadrature squeezing with time are discussed.The preparation of maximally entangled state between the atom and the graphene membrane can be realized.It is found that the entanglement between the atom and the cavity field increases with the increases of the coherent angle.We demonstrate how to switch from no squeezing to large squeezing by manipulating the initial state of an atom.Moreover,the squeezed state of periodic phonon field with longtime and high-degree can be generated.Further,the influence of dissipation on the entanglement and quadrature squeezing of the system is analyzed.At the same time,the optical properties and precision measurement of the NV center in diamond coupled the nanomechanical resonator system are also studied.Using the all-optical pump-probe technology and the Heisenberg-Langevin method,the absorption spectrum is analyzed by adjusting the system parameters.From the above analysis,we found that the width and size of the electromagnetically induced transparency window can be manipulated by changing the system parameters.Finally,it is possible to measure the system coupling strength,mechanical resonator frequency and lifetime according to the relationship between the peaks in the absorption spectrum.