Colloquium

  • Defect-based quantum systems in solids

  • Speaker : 이상윤/ Sang-Yun Lee
    Affiliation : KIST
    Date : September 12, 2018 4:00 PM
    Place : Building 110 Room N103
    Contact : jehyungkim@unist.ac.kr
    Host : 김제형
  • Abstract

  • High purity single crystalline solids can be used as a robust platform for quantum information research since isolated defects, which resemble isolated single atoms when phonon coupling is efficiently suppressed, can be created in the middle of almost noise-free environment. Among various defects which can be created artificially, color center in wide-bandgap semiconductors such as diamond and silicon carbide have been used to demonstrate various proof-of-idea experiments for quantum information and also various quantum applications such as quantum metrology. Even though small size integrated qubit devices consisting of a few entangled spin qubits have been demonstrated, there remain open questions about whether this physical system will allow building large quantum devices in which many qubits can interact with each other without losing their coherent properties.

    Managing spin-spin interaction among defects spins near each other is a typical method to enable quantum connection among spin qubits. In addition, the optical transitions strongly correlated with spin states of the color centers allow another pathway for integrating individual qubits. One example is the photonic quantum network which can meditate entanglement among distant spin qubits via spin-selective optical transitions. The spin-to-photon interface based on a color center in diamond has shown the entanglement rate exceeding the decoherence rate of two distant spin qubits. In parallel, there have been efforts for finding novel color centers in various large bandgap materials whose ability as a spin-to-photon interface may exceed that of the diamond color centers. The color centers in silicon carbide are candidates since well-developed device fabrication techniques exist and efficient spin-to-photon interfaces have been found recently. In this presentation, a broad review about the quantum technology based on color centers in solids will be provided, and a summary about recent progresses will be presented as well.