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Q: Fachverband Quantenoptik und Photonik
Q 57: Quantum Information (Quantum Repeater)
Q 57.6: Talk
Friday, March 13, 2020, 12:30–12:45, e001
Stabilization of a high-finesse cavity with an Erbium doped crystal in a closed-cycle cryostat — •Alexander Ulanowski1, Benjamin Merkel1, and Andreas Reiserer1,2 — 1MPI of Quantum Optics, Garching, Germany — 2Munich Center for Quantum Science and Technology (MCQST), Ludwig-Maximilians-Universität München, München, Germany
Cryogenic optical resonators are promising for the implementation of quantum repeaters based on dopants in solid-state systems. Due to mechanical vibrations in a closed-cycle cryostat, such resonators require elaborate passive and active stabilization. The presence of mechanical resonances and anti-resonances in the resonator mount can however limit the bandwidth of active feedback when using ordinary controllers, e.g. a proportional-integral-derivative controller (PID).
We overcome this limitation by using a Finite Impulse Response (FIR) filter realized digitally on a field-programmable gate array device to cancel out these mechanical resonances and increase the unity gain frequency. [1] In combination with passive stabilization of our high-finesse resonator (F≈105), we achieve a sub-pm stability at a temperature of 2K. This allows us to observe emission of erbium ions, doped into a crystal that is embedded in the resonator, with a Purcell enhancement factor of several hundreds.
[1] Ryou and Simon, Rev. Sci. Instrum. 88, 013101 (2017)