Micromotion minimisation by synchronous detection of parametrically excited motion

Abstract

Precise control of charged particles in radio-frequency (Paul) traps requires minimising excess micromotion induced by stray electric fields. We present a method to detect and compensate such fields through amplitude modulation of the radio-frequency trapping field. Modulation at frequencies close to the motional modes of the trapped particle excites coherent motion whose amplitude linearly depends on the stray field. In trapped-ion experiments, this motion can be detected by recording the arrival times of photons scattered during laser cooling. Only a single laser beam is required to resolve fields in multiple directions. In a demonstration using a ${}^{88}{\mathrm{Sr}}^{+}$ ion in a surface electrode trap, we achieve a sensitivity of $0.1\mathrm{V}{\mathrm{m}}^{-1}/\sqrt{\mathrm{Hz}}$ and a minimal uncertainty of $0.015\mathrm{V}{\mathrm{m}}^{-1}$.

11 pages, 6 figures (+appendix of 5 pages, 4 figures)

References in corpus (3)

• Quantum computing with trapped ions
• An ${}^{27}$Al${}^{+}$ quantum-logic clock with systematic uncertainty below $10^{-18}$
• Microwave Near-Field Quantum Control of Trapped Ions