Quantum Optics and Quantum Manipulation of Ultracold Atoms

I. Coordinator:

  • Ying-Cheng Chen (陳應誠, IAMS)

II. Core Members:

  • Core members(Expt.)
  • Ite A. Yu (余怡德, NTHU), Ming-Shien Chang (張銘顯, IAMS), Yu-Ju Lin (林育如, IAMS), Shih-Kuang Tung (童世光, NTHU), Hoi-Io Chun(許耀銓, NTHU), Yi-Hsin Chen (陳易馨, NSYSU)
  • Core members (Theory)
  • Guin-Dar Lin(林俊達, NTU), Wen-Ten Liao (廖文德, NCU), Daw-Wei Wang(王道維, NTHU), Ray-Kuang Lee(李瑞光, NTHU), Shih-Chuan Gou(郭西川, NCCU). Sungkit Yip(葉崇傑, IoP, AS), Wen-Chin Wu(吳文欽, NTNU)
  • Participants
  • Postdocs
  • Hsiang-Hua Jen(任祥華, IoP, AS), You-Lin Chuang(莊又霖, NCTS), C.- H. Hsueh (薛哲修, NTNU),Y.- K Liu(劉翼剛,NCCU) etc…
  • Students
  • many students among the groups of the core members.

Research Themes:

  • Cooperative atom-photon interactions
  • For dense atomic ensemble, the resonant dipole-dipole interactions among the atoms through exchange of photons introduce cooperative radiation phenomena such as cooperative Lamb shift, superradiance and subradiance. This is a theoretically challenging problem since it is essentially a many-body problem which could involve multiple photon excitations. However, the experiments are relatively simple to be implemented just by dense or optically dense atomic ensembles with simple spectral measurement. So far, there is still no satisfactory theory which could well explain the experimental results. Such research has drawn significant attentions in recent years. Besides, there are many new proposals to utilize the cooperative interactions in the system like atoms inside a one-dimensional waveguide or two-dimensional atomic arrays to enhance the fidelity of EIT-based optical quantum memory. In the experimental team of Ying-Cheng Chen, they had observed many unresolved phenomena which related to cooperative interactions. There have been a close cooperation between Guin-Dar Lin, Hsiang-Hua Jen, Ming-Shien Chang and Ying- Cheng Chen on such a topic for more than three years. They have done many published works along this direction. Wen-Te Liao is also working on related topic and may actively participate in the link. There are many rich problems await further exploration.
  • Yi-Hsin Chen in NSYSU has initiated an experiment with atom-nanofiber system. Cooperative interaction and chiral effect are crucial in such a system. She, Hsiang- Hua Jen, Guin-Dar Lin may initiate close cooperation on such a topic.
  • In a superconducting artificial atoms and microwave system, Hoi-Io Chun also observed cooperative phenomena. He and Guin-Dar Lin has initiated a cooperation. Since the superconducting system involved less atoms and is specified in a welldefined geometry, the theory could provide a direct calculation and test. Such a cooperation could help both sides to gain physical insights.

  • Rydberg atomic ensemble with emphasis on quantum optics
    Due to the strong-and long-range dipole-dipole interactions, systems of Rydberg atoms are identified as new paradigm for implementation of quantum gates, studies on quantum nonlinear optics and new exotic quantum phases. Ite A. Yu (NTHU) has initiated an experiment on quantum nonlinear optics with Rydberg atoms. The theoretical support on the quantum nonlinear optics with Rydberg gases is relatively lacking. Yu has close cooperation with NCTS regular visitor Gediminas Juzeliunas and his postdoc Julius Ruseckas on such a topic. They have produced some results and will continue such a cooperation. Yu and Ray-Kuang Lee and Y.-L. Chuang also has constant cooperation on squeezed light generation based on cold atoms.
  • Quantum Simulation with quantum gases
    Recently, Yu-Ju Lin’s research on the spin-orbit-coupled quantum gas in synthetic gauge field has many good results. They will continue explore the superfluidity in such a system. She, Ming-Shien Chang and Sungkit Yip has a constant cooperation and should continue. Y-J Lin also cooperate closely with a Japan scholar Yuki Kawaguchi. ECP1 may invite Yuki to visit Taiwan. M.-S. Chang’s research focuses on spinor condensates with one-dimensional optical lattices. Shih-Kuang Tung is building a new quantum gases system with a focus on many-body localization. They may cooperate with local theorists like Sungkit Yip, Wen-Chin Wu and Shih-Chuan Guo on such topics. Actually, Y-J Lin and M-S Chang will hire W.-C. Wu’s postdoc, C-H Hsueh, to help them closely on the theory part.

Tentative plan of activities:
  • 1. It will be very helpful for domestic scholars to invite a few international visitors (not at once and not necessary to be professors, postdoc is fine) to have a short term stay (around one to two weeks). This allows domestic scholars to learn some detailed knowledge and skills on certain topics and may establish useful collaboration in the future. This is usually more effective than holding a workshop with multiple visitors. In 2019, Y-J Lin may invite her collaborator Yuki and Ite Yu may invite his collaborator Julius to Taiwan for a close discussion.
  • 2. We encourage short-term visit of postdocs or senior graduate students from theoretical groups to experimental teams of the core members to exchange ideas and findings. We hope to establish in-depth understanding on the detailed issues in both sides and therefore, an actual in-depth collaboration. Based on the running experiences in the past two years, we found that this is a very productive way to enhance the collaboration between experimental and theoretical members. A good example this year is that Y-J Lin and M-S Chang will hire W-C Wu’s postdoc C-H Hsueh to initiate such a close cooperation.
  • 3. We have a monthly or bi-monthly discussion meeting to bring together people sharing common interest for brain-storming. This actually bring very intense discussion. We plan to maintain this activity. But we have to squeeze its frequency (probably bi-monthly) to choose topic that at least two teams sharing the common interest to maintain the momentum.

VExpected achievements:

  • The major concern of this group is to establish a platform to promote the interaction and collaboration between theorists and experimentalists. Constant and frequent discussions among the core members sharing the common interest is the most-natural and effective way to initiative active researches. To allow constant and frequent visits for postdocs or senior graduate students among different groups of the core members is also a very useful and effective way. Based on the experiences in the past two years, our program has established a quite productive publications with experimental and theoretical collaborations. We should target more postdocs or senior students to maintain and enhance the collaboration activity.

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