2018/12/13 by Yang Wu, Wenqiang Liu, Jianpei Geng +5 · 4 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1126/science.aaw8205
arxiv created 2018/12/13 · arxiv updated 2019/06/19
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 (PT) symmetry can still display entirely real spectra. The Hermiticity requirement may be replaced by 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 PT symmetric physics in quantum systems.Here we report the first observation of the PT symmetry breaking in a single spin system. We have developed a novel method to dilate a general PT symmetric Hamiltonian into a Hermitian one, which can be realized in a practical quantum system.Then the state evolutions under PT symmetric Hamiltonians, which range from 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 PT symmetric Hamiltonian in quantum systems.