Experimental Study Of Carbon Nanotube Resonator

In recent years,due to the maturity of micro-nano fabrication technology,artificial nano-structures are widely studied,people actively explore the mechanical,thermal,optical and electromagnetic properties in a variety of nano-materials,among which the nano-mechanical resonator joins great attention for its potential use to study the light-matter interactions.The international research group reported a series of basic physical research results on the two systems of photonic crystal mechanical resonator and superconducting aluminum-drum electromechanical resonator,for example,the macro quantum mechanics ground state of micro-scale mechanical resonator cooled by light or microwave,the generation of quantum squeezing state of phonon mode,and so on.These studies show that the mechanical resonators or phonons can act in the interaction of light and matter with the quantization form.Similar to quantum optics,this discipline on the interaction of phonons and matter is called quantum acoustics.Besides photonic crystal mechanical resonator and superconducting aluminum-drum mechanical resonator,a series of other mechanical resonators have been studied such as graphene,carbon nanotube,and WS2,due to the rise of new low-dimensional materials.These types of mechanical resonators,in addition to their good basic properties,can also be used to study the coupling between the mechanical vibrations and the Landau level in the magnetic field,or the quantum dot based qubits,which are excluded by the simple optical mechanical systems.On the other hand,quantum computing,based on semiconductor quantum dots,is regarded as one of the effective systems due to the maturity of modern semiconductor technology.With the increasing number of the manipulated qubits,people have been exploring the use of superconducting microwave cavity to couple semiconductor qubits in distance,and have achieved some progress,but it is still in the immature stage.Comparison of microwave photons and phonons,both of which are Bosons,it is easy to think whether the phonon cavity can be used to couple the qubits,and the phonon carriers are just the nano-mechanical resonators.Therefore,we began to study carbon nanotube based electromechanical resonator and achieved a series of good results.This thesis mainly introduces the following:1.Give a more detailed introduction to the international research progress in the field of nano-mechanical resonators,including photonic crystal mechanical resonator,superconducting aluminum-drum mechanical resonator,carbon nanotube mechanical resonator,and so on.The most basic concepts for carbon nanotube quantum dots are also presented.2.Introduce the micro-nano fabrication equipment,low-temperature equipment,and electrical measurement instruments used in the sample fabrication of carbon nanotube mechanical resonator and ultra-low temperature measurement.Combined with the samples used in the experiment,the sample fabrication procedure and low temperature measurement method of carbon nanotube mechanical resonators are introduced in detail.3.The experimental results show that the vibrations of two mechanical resonators are coupled when the frequencies of them are tuned very close to each other.The vibrations of the two resonators superpose to produce a frequency splitting phenomenon,indicating the strong coupling region.4.The researchers experimentally find that there exist a variety of vibration modes in carbon nanotube mechanical resonators.Predecessors reported there was a strong coupling between different modes when the amplitudes were in the large nonlinear region.We couple two independent vibration modes in the linear region of the small amplitudes by introducing an external pump microwave,and also reach the strong coupling region.5.The researchers study the back-and-forth coherent exchange of phonon energy in two different vibration modes of a mechanical resonator,and realize classical Rabi oscillations.The two modes of the mechanical resonator are analogy to the quantum two-level system,and then people can simulate the quantum Rabi oscillations by the mechanical resonators.This thesis shows several innovations as:1.Achieve the strong coupling of the two neighbor resonators for the first time in the carbon nanotube system.2.Demonstrate the dynamic strong coupling between different modes in the linear region of the carbon nanotube system.3.Besides the realization of the dynamic coupling between two vibration modes,the researchers also manipulate the mechanical resonator in the time domain to achieve a classical Rabi oscillations process,which can be used to simulate the quantum two-level systems.