Research output: Contribution to journal › Journal article
|<mark>Journal publication date</mark>||7/05/2010|
|<mark>Journal</mark>||Physical review letters|
|Number of pages||4|
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.