The team led by academician GUO Guangcan from University of Science and Technology of China (USTC) of Chinese Academy of Sciences (CAS) has made important progress in the research of non-Hermitian quantum simulation. Prof. LI Chuanfeng, Prof. TANG Jianshun, Dr. WANG Yitao and others in the team realized the construction of recycling-structure parity-time (PT) symmetric quantum simulator for the first time in the world. They observed the dynamics of quantum states in PT symmetric system based on the quantum simulator. This work provides a practical experimental platform for in-depth study of non-Hermitian quantum physics, and was published in Physics Review Letter on June 11th, 2020.
The PT symmetric system is a type of non-Hermitian physical system controlled by a dynamical Hamiltonian that satisfies parity-time inversion invariance. Compared with the Hermitian system, the PT symmetric system also possesses the real eigenenergy spectrum, and could hold the steady dynamical eigenmode. On the other hand, the dynamical eigenmode in PT symmetric system possesses the special non-orthogonal nature, and the system energy band exhibits the unique topology near the exceptional point. Therefore, the PT symmetric system possesses a variety of novel non-Hermitian physical properties, and has drawn extensive attention in the research field.
PT symmetric dynamics has been observed in a variety of classic systems and has exhibited great application ability. In the quantum field, however, due to the difficulty of quantum-system control, the intensive experimental research of various quantum properties and applications of PT symmetric dynamics is still lacked.
Based on the self-designed non-Hermitian quantum gate and the single-photon recycling evolution structure, researchers realized the construction of recycling-structure PT symmetric quantum simulator for the first time. The quantum simulator can effectively simulate the dynamical process of PT symmetric quantum system, and output the evolved quantum state in discrete time mode. Based on the quantum simulator, the research group observed the dynamical behaviors of quantum state in the PT symmetric unbroken and broken regions, and investigated the phase-transition-criticality phenomenon of the quantum-state dynamics near the exceptional point. This work provide an effective experimental platform for the future research of PT symmetric and other non-Hermitian quantum physics.
Schematic of recycling-structure PT symmetric quantum simulator (Image by WANG Yitao et al.)
Paper Link:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.230402
(Edited by LU Hongyu, USTC News Center)