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arXiv · 1812.05226

Observation of parity-time symmetry breaking in a single spin system

Yang Wu·Wenqiang Liu·Jianpei Geng·Xingrui Song·Xiangyu Ye·Chang-Kui Duan·Xing Rong·Jiangfeng Du
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Abstract

A fundamental axiom of quantum mechanics requires the Hamiltonians to be Hermitian which guarantees real eigen-energies and probability conservation. However, a class of non-Hermitian Hamiltonians with Parity-Time ($\mathcal{PT}$) symmetry can still display entirely real spectra. The Hermiticity requirement may be replaced by $\mathcal{PT}$ symmetry to develop an alternative formulation of quantum mechanics. A series of experiments have been carried out with classical systems including optics, electronics, microwaves, mechanics and acoustics. However, there are few experiments to investigate $\mathcal{PT}$ symmetric physics in quantum systems.Here we report the first observation of the $\mathcal{PT}$ symmetry breaking in a single spin system. We have developed a novel method to dilate a general $\mathcal{PT}$ symmetric Hamiltonian into a Hermitian one, which can be realized in a practical quantum system.Then the state evolutions under $\mathcal{PT}$ symmetric Hamiltonians, which range from $\mathcal{PT}$ symmetric unbroken to broken regions, have been experimentally observed with a single nitrogen-vacancy (NV) center in diamond. Due to the universality of the dilation method, our result opens a door for further exploiting and understanding the physical properties of $\mathcal{PT}$ symmetric Hamiltonian in quantum systems.

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Yang Wu, Wenqiang Liu, Jianpei Geng, Xingrui Song, Xiangyu Ye, Chang-Kui Duan, Xing Rong, Jiangfeng Du. 2018-12-13. Observation of parity-time symmetry breaking in a single spin system. https://doi.org/10.1126/science.aaw8205

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