Professor Zhu Xiaobo, from the Institute of Physics, Chinese Academy of Sciences, deliv-ered a talk “superconducting qubits and quantum hybrid systems” in our institute, du-ring the visit of the group for bound-system quantum information processing.
Quantum computers, a brand-new kind of the computers based on quantum theory, are the physical devices for high-speed mathematical and logical operations as well as quantum information storage and processing, following the rules of quantum mechanics.Compared with the classical counterparts, quantum computers have overwhelming advantages inthe search algorithm and the factorization of large numbers, which can be widely applied to the information security, large database search and quantum simulation. There are various physical systems hopeful for executing quantum computation, where superconducting qubits are very promising candidates due to significant advantages in good scalability, precise controllability and easy coupling. However, the technology regarding superconducting qubits is limited by the short decoherence time. On the other hand, the spins in some solid-state systems are usually of long decoherence time but poor scalability. Therefore, it is advisable to make use of the advantages of both the systems by coupling them as a hybrid quantum computer.
Professor Zhu has been engaged in the research of superconducting flux qubits and Josephson junctions for a long time and published many high-level academic papers. The energy-tunable superconducting flux qubit designed and fabricated by his team has reached the decoherence time up to 4 microseconds, which is the best in the relevant area. Professor Zhu has realized for the first time the coupling of the superconducting flux qubit to the diamond nitrogen-vacancy (NV) center ensemble, which is a breakthrough in the NV ensemble quantum computation.
In his talk, Professor Zhu introduced the achievements his team made recently in the study of the hybrid system consisting of superconducting qubits and NV ensembles. He demonstrated the long-decoherence-time energy-tunable superconducting qubit designed and fabricated by them, and presented their experiments coupling the superconducting qubit to the NV ensemble. He also explained the dark state of the NV collective mode found experimentally. Finally, he analyzed the advantages and disadvantages of the hybrid systems, and made a prospect forecast for the future work.
The talk has greatly attracted the audiences. After the talk, an extensive discussion was made on the related problems.