We report amplification of electromagnetic waves by a single artificial atom in open 1D space. Our three-level artificial atom -- a superconducting quantum circuit -- coupled to a transmission line presents an analog of a natural atom in open space. The system is the most fundamental quantum amplifier whose gain is limited by a spontaneous emission mechanism. The noise performance is determined by the quantum noise revealed in the spectrum of spontaneous emission, also characterized in our experiments.
@article{arxiv.1004.3864,
title = {Ultimate on-chip quantum amplifier},
author = {O. Astafiev and A. A. Abdumalikov and A. M. Zagoskin and Yu. A. Pashkin and Y. Nakamura and J. S. Tsai},
journal= {arXiv preprint arXiv:1004.3864},
year = {2015}
}
Comments
4 pages, 4 figures + supplemenntary materials accepted for publication in Phys. Rev. Lett.