# Poster Presentation

Thanks for my boss’s support, I have a chance to give a poster presentation on International Conference on Quantum Optics, Hong Kong. The name of it is “Simple Schemes of CQED for Realizing Swap, Entangling and CNOT Quantum Gate”, which can be found in this webpage. Here is the tentative abstract of the presentation.

We consider the two cavities which are spatially separated and connected by an optical fibre. There are multi Lambda atoms in each of the cavities. The atoms are resonantly interacting to fields and there is no direct interaction between the atoms. We show that perfect swap, entangling and CNOT quantum gates can be realized between the two atoms clusters. Compared with the single atom scheme, we find that the atoms clusters scheme can increase the speed of swap, entangling and CNOT gates. The sensibility of these gates to parameters in the models with consideration is investigated. Finally we take account the effect of dissipation and show that such gates are almost feasible with the present technology.

This is the first time I attend the academic conference and do presentation in English. I wish I can do it well.

# Xfig and LaTeX

(1)打开Xfig，画好你的图。

(2)选择大写的T，然后在窗口底部的”Text Flags hidden=off”点击，把”Special Flag”从Normal改成Special，选择确定。

(3)然后在你要写LaTeX命令的地方单击鼠标左键，进图编辑模式，开始写入LaTeX命令，比如$frac{1}{N}$。写完后保存文件。

(4)在文件菜单中选择把文件导出，在导出对话框中选择“Combined PS/LaTeX (both parts)”，然后点击导出。

(5)这样就有三个文件，后缀分别是.fig，.pstex，.pstex_t。第一个是你编辑的源文件，第二个是是导出的图片文件，第三个包含图片文件中的LaTeX命令。

(6)把后两个文件拷贝到你的LaTeX论文所在目录，在LaTeX文件中使用input{}命令把后缀为pstex_t的文件导入你要插入图片的地方即可。

(7)注意！如果你没有用color宏包，那么你需要手动修改pstex_t文件，把所有”color[rgb]{0,0,0}”都删除，否则编译LaTeX文件有可能会不正常。

# We are little late

I am sad today for I notice that someone else have done similar work which we are doing now. In this competition, we are little late. Though the two works are not the same, our work is more general, this finding makes me feel that the value of our work decreased.

Why I am so desjected? Because this work is my favorite. When the new idea appeared in my brain, I was so excited and felt that I was the first one to get this idea. But now I found I was wrong. This work is not excellent, but it is my first creation. So someone else having done a similar work is a big beat to me, espacially after I finding that their articles were published in the last year and this year.

Next time when I got a new idea, I should go to check if anyone else have done it before. I must admit that if I can get a idea, many other people can, too.

# Quantum computing via Buckyball

I posted an entry few days ago which said that Iijima would come to give a lecture in the nanoforum of our university. Yesteday I listened other two lectures in the nanoforum about buckyball by Takeshi Akasaka and Shigeru Nagase.

Akasaka’s works focus on the experimental organic chemstry. His group made a lot of effort to investigate the feather endohedral fullerene molecules. The name of his lecture is “New Progress in Chemistry of Endohedral Metallofullerenes”. Nagase is a theoretical computing chemistist. He and Akasaka collaborate and have maken many good works in quantum chemistry computing. His lecture was named “Nano-molecules and Computational Chemistry”.

The Japanese accents of their English troubled me a lot to follow their lecture. At last, by the help of slides, I catch up with some information. I guess maybe this endohedral metallofullerenes could be used to do quantum computing during the lecture. But this idea only lived a few seconds in my brain for I have no idea on fullerence.

Today, I find a paper in arxiv that investigated posibility to use the model of endoheral metallofullences to realise quantum computing. Here is the abstract

We have studied a system composed by two endohedral fullerene molecules. We have found that this system can be used as good candidate for the realization of Quantum Gates Each of these molecules encapsules an atom carrying a spin,therefore they interact through the spin dipole interaction. We show that a phase gate can be realized if we apply on each encased spin static and time dependent magnetic field. We have evaluated the operational time of a $\pi$-phase gate, which is of the order of ns. We made a comparison between the theoretical estimation of the gate time and the experimental decoherence time for each spin. The comparison shows that the spin relaxation time is much larger than the $\pi$-gate operational time. Therefore, this indicates that, during the decoherence time, it is possible to perform some thousands of quantum computational operations. Moreover, through the study of concurrence, we get very good results for the entanglement degree of the two-qubit system. This finding opens a new avenue for the realization of Quantum Computers.

They theoretically shown the possibility of quantum comupation via buckyball. Thanks to the works of chemistists such as Takeshi Akasaka and Shigeru Nagase et al., this scheme is very promising and will be realised in experiment soon. This is another example that chemistry and physics are connected closely.