Phase locking of a semiconductor double quantum dot single atom maser

TL;DR

This paper demonstrates phase locking of a semiconductor double quantum dot single atom maser using injection locking, achieving significant phase noise reduction and tunable emission spectra, including frequency combs.

Contribution

It experimentally shows phase stabilization of a DQD maser via injection locking, aligning with Adler's theory and enabling rapid gain medium switching for frequency comb generation.

Findings

Maser phase locked with -99 dBc/Hz phase noise at 1.3 MHz offset

Injection locking range consistent with Adler's theory

Frequency comb linewidth reduced from ~8 kHz to less than 1 Hz

Abstract

We experimentally study the phase stabilization of a semiconductor double quantum dot (DQD) single atom maser by injection locking. A voltage-biased DQD serves as an electrically tunable microwave frequency gain medium. The statistics of the maser output field demonstrate that the maser can be phase locked to an external cavity drive, with a resulting phase noise of -99 dBc/Hz at a frequency offset of 1.3 MHz. The injection locking range, and the phase of the maser output relative to the injection locking input tone are in good agreement with Adler's theory. Furthermore, the electrically tunable DQD energy level structure allows us to rapidly switch the gain medium on and off, resulting in an emission spectrum that resembles a frequency comb. The free running frequency comb linewidth is ~8 kHz and can be improved to less than 1 Hz by operating the comb in the injection locked regime.