Ultimate quantum limit for amplification: A single atom in front of a mirror
Journal article, 2021

We investigate three types of amplification processes for light fields coupling to an atom near the end of a one-dimensional (1D) semi-infinite waveguide. We consider two setups where a drive creates population inversion in the bare or dressed basis of a three-level atom and one setup where the amplification is due to higher-order processes in a driven two-level atom. In all cases, the end of the waveguide acts as a mirror for the light. We find that this enhances the amplification in two ways compared to the same setups in an open waveguide. Firstly, the mirror forces all output from the atom to travel in one direction instead of being split up into two output channels. Secondly, interference due to the mirror enables tuning of the ratio of relaxation rates for different transitions in the atom to increase population inversion. We quantify the enhancement in amplification due to these factors and show that it can be demonstrated for standard parameters in experiments with superconducting quantum circuits.

Waveguide quantum electrodynamics

Circuit quantum electrodynamics


Quantum optics

Quantum mechanics


Emely Wiegand

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

P. Y. Wen

National Chung Cheng University

Per Delsing

Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology

Io Chun Hoi

National Tsing Hua University

Anton Frisk Kockum

Chalmers, Microtechnology and Nanoscience (MC2), Applied Quantum Physics

New Journal of Physics

1367-2630 (ISSN)

Vol. 23 4 043048

Kvantplasmonik – en teknologi för foton-fotonväxelverkan på kvantnivå vid rumstemperatur

Swedish Research Council (VR) (2016-06059), 2017-01-01 -- 2022-12-31.

Subject Categories

Atom and Molecular Physics and Optics

Other Physics Topics

Condensed Matter Physics



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