| Nowadays,quantum information is a frontier research field that spans the fields of physics and information science,and has many branch research directions.In China,research groups related to quantum information have carried out a lot of research work in different directions in this field.This paper mainly introduces one of the directions:quantum regulation based on solid-state spin.The main research object of this paper is the NV center existing in diamond,which is mainly composed of vacancies and nitrogen atom impurities caused by diamond lattice defects.On the NV-based quantum information experimental platform,our goal is to be able to control the quantum state of the NV center.In order to achieve this goal,since the quantum state of the NV center inside the diamond is uncertain,firstly we must apply a532 nm laser to initialize the quantum state,so that its quantum state is kept as high as possible with the m_s=0 state,then a continuous laser and a high-intensity magnetic field are applied to the NV center,and the fluorescence emitted by the NV center is collected with the microwave frequency sweep,and the fluorescence intensity is recorded to obtain an ODMR spectrum of the NV center.Since NV has four axes,we choose the main axis.Due to the Zeeman effect(the atomic spectrum will split when the magnetic field is applied),the spindle will have two fluorescence intensity troughs near the2870MHz frequency point of the ODMR spectrum,which are corresponding to two quantum states of the NV center,ie m_s=±1.We selectively apply a specific frequency microwave&RF signal according to the frequency points on the ODMR spectrum corresponding to the two quantum states,so as to couple the m_s=0 state of the NV center to the m_s=1 or m_s=-1 state and realize the manipulation of the NV quantum state.The main work of this paper is to build a microwave system that can provide microwave signal and microwave alternating magnetic field with adjustable frequency and arbitrarily adjustable phase for quantum control experiments of diamond NV center.In order to achieve this goal,based on the principle of single sideband signal modulation,a microwave bridge in a microwave system is firstly built by using a series of microwave devices.After debugging,the single sideband modulation,frequency adjustment and phase adjustment of the microwave signal are realized.Secondly,we use the traditional slotline transmission line with the characteristics of low loss and no cutoff frequency and its derivation structure?-type open-end slotline with good radiation characteristics to design a special radiation structure suitable for diamond NV center experiment.The radiation structure can convert the microwave&RF pulse signals which have experienced single sideband modulation,switching modulation and amplification of power amplifier,into an alternating magnetic field,thereby acting on the NV center.Then we have achieved low-cost fabrication of the radiation structure using magnetron sputtering,laser etching and electrochemical plating processes.After being tested by instruments such as vector network analyzer,the radiation structure has been applied to the quantum experimental platform of diamond NV center,and has achieved good experimental results.Finally,based on the above technical supports,this paper completes the experimental reconstruction of a single electron spin quantum state of diamond NV center based on Wigner function. |
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