We propose a method to subtract a photon from a double sideband mode of continuous-wave light. The central idea is to use phase modulation as a frequency sideband beamsplitter in the heralding photon subtraction scheme, where a small portion of the sideband mode is downconverted to the carrier frequency to provide a trigger photon. An optical Schr\"odinger's cat state is created by applying the propesed method to a squeezed state at 500MHz sideband, which is generated by an optical parametric oscillator. The Wigner function of the cat state reconstructed from a direct homodyne measurement of the 500MHz sideband modes shows the negativity of W(0,0)=−0.088±0.001 without any loss corrections.
@article{arxiv.1804.08905,
title = {Schr\"odinger's cat in an optical sideband},
author = {Takahiro Serikawa and Jun-ichi Yoshikawa and Shuntaro Takeda and Hidehiro Yonezawa and Timothy C. Ralph and Elanor H. Huntington and Akira Furusawa},
journal= {arXiv preprint arXiv:1804.08905},
year = {2018}
}