The been my impetus for study. Attracted

The eagerness to acquire a deeper understanding of the physical world has always
been my impetus for study. Attracted by the incredible property of light, I chose optics
as my major in undergraduate study. In particular, I developed great interest in
photonics and quantum optics. A persistent desire to pursue relevant knowledge now
motivates me to apply for graduate program at Yale University. In the fall of 2016, I joined the Chinese Academy of Science Key Lab of Quantum
Information. Research about quantum entanglement, which is the most fascinating
property of quantum systems, soon caught my attention. I thus took part in a research
project supervised by Prof. Chuan-Feng Li, which tries to utilize the violation of Bell
inequality to reveal the property of unknown quantum states. Such a technique, so-called self-testing, enables us to evaluate entangled states in a device-independent
way. Despite the obstacle of facing elaborate optical systems in our experiment, I
managed to get familiar with these systems and helped build several necessary
components. After months of effort, we have now successfully built a system for
preparing and testing 2-qubit and 2-qudit (4-dimensional) entanglement and our
experiment is currently underway. Involvement in this project greatly promoted my
experimental skills, which I believe will be advantageous when facing related optical
projects. During the experiment, I noticed that finding maximal violation of certain Bell
inequality for unknown quantum states tended to be a difficult, but important task, since it is usually the first step of Bell experiments. The method we use in our
experiment, which is a commonly used one, is to compute Bell violation theoretically
with the result of quantum tomography. This approach, however, will become
impractical when facing large-scale systems and untrustworthy devices. Inspired by
these difficulties, I proposed that the stochastic gradient ascent algorithm could be
implemented. With rigorous tests and simulations, I reached the conclusion that my
method is superior to the traditional method in both error robustness and device
dependence, allowing it to be utilized in our future experiments about Bell nonlocality. A paper about this work, on which I am the first author, was recently published in
Phys. Rev. A (PRA 96, 052310). Thanks to this experience, I have learned to conduct
research independently and thoroughly. In addition to joining research projects in my own school, I also participated in a
research internship at the Institute of Quantum Science and Engineering at Texas
A&M University (TAMU) in the summer of 2017. During my two-month stay at
TAMU, I conducted quantum optics research which originated with Prof. Da-Wei
Wang’s idea that atomic entanglement between photon sources can be generated in the
Hong-Ou-Mandel (HOM) experiment. Discovering that a lot of problems should be
solved before possible experimental realization, I developed my research trying to
improve this proposal. Firstly, I demonstrated that light fields can be applied on the
entangled state to control the relative paths of two emitted photons. As a result, traditional HOM effect can be reconstructed without photon interference. I also found
that using trapped ions with Raman-like transition instead of spontaneous emission
can greatly improve the controllability and success probability of our system. Finally, I referred to the quantum Monte Carlo method and conducted a simulation to prove
the versatility of my proposal under certain experimental errors. A paper including all
these processes and findings, which has been submitted to Journal of Modern Optics, can be found on arXiv:1708.09436. In the end of July 2017, our department director, Dr. Marlan O. Scully, held a
symposium about quantum optics and invited us to present short talks and posters
during the conference. After my presentation, several conference attendees came to
my poster for further discussions. While demonstrating my capability to express
academic ideas clearly, I also got helpful advice for continuing my project. This
exciting opportunity to present my research in front of many famous physicists greatly
strengthened my determination to continue working in the field of science. These experiences provided me great opportunities to deepen my understanding of
optical science and engineering. I developed an insightful and analytical way of
thinking as well as advanced experimental skills through my research experiences. Not to mention solid theoretical knowledge related to photonics, optoelectronics and
quantum physics. Equipped with these abilities, I expect to conduct beneficial
researches about optical science in the future, wishing to widen and deepen its
application in different fields. My undergraduate studies will soon come to an end, but I firmly believe that I should
continue onto further research to learn more about optical science. Therefore, I think
that graduate program at Yale University will be a perfect choice for me. For example, I find several research projects about optoelectronics (by Prof. Jung Han and Prof. Fengnian Xia), quantum optics and optomechanics (by Prof. Hong Tang) particularly
attractive. While learning to be a comprehensive researcher with the help of Yale’s
successful faculty, I believe I will be able to positively influence the development of
knowledge. In a word, I have already joined several research projects and written successful
papers about my own research, showing my potential to have impact on the cutting
edge of optical technology. Toward a successful academic career, unflagging passion
and determination will continue to animate me through graduate study. If afforded this
incredible opportunity, I will take full advantage of the experience to contribute and
learn the most that I can from professors, peers, and the Yale community.