Ultrasensitive force and displacement detection using trapped ions

Abstract

The ability to detect extremely small forces is vital for a variety of disciplines including precision spin-resonance imaging, microscopy, and tests of fundamental physical phenomena. Current force-detection sensitivity limits have surpassed 1 $aN/\sqrt{Hz}$ (atto $=10^{-18}$) through coupling of micro or nanofabricated mechanical resonators to a variety of physical systems including single-electron transistors, superconducting microwave cavities, and individual spins. These experiments have allowed for probing studies of a variety of phenomena, but sensitivity requirements are ever-increasing as new regimes of physical interactions are considered. Here we show that trapped atomic ions are exquisitely sensitive force detectors, with a measured sensitivity more than three orders of magnitude better than existing reports. We demonstrate detection of forces as small as 174 $yN$ (yocto $=10^{-24}$), with a sensitivity 390$\pm 150$ $yN/\sqrt{Hz}$ using crystals of $n=60$ ${}^9$Be${}^{+}$ ions in a Penning trap. Our technique is based on the excitation of normal motional modes in an ion trap by externally applied electric fields, detection via and phase-coherent Doppler velocimetry, which allows for the discrimination of ion motion with amplitudes on the scale of nanometers. These experimental results and extracted force-detection sensitivities in the single-ion limit validate proposals suggesting that trapped atomic ions are capable of detecting of forces with sensitivity approaching 1 $yN/\sqrt{Hz}$. We anticipate that this demonstration will be strongly motivational for the development of a new class of deployable trapped-ion-based sensors, and will permit scientists to access new regimes in materials science.

Expanded introduction and analysis. Methods section added. Subject to press embargo

References in corpus (5)

• Nanomechanical motion measured with precision beyond the standard quantum limit
• Ion traps with enhanced optical and physical access
• Trapped-ion probing of light-induced charging effects on dielectrics
• Temperature Dependence of Electric Field Noise Above Gold Surfaces
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Cited by in corpus (3)

• Superconducting microfabricated ion traps
• Interferometry with Synthetic Gauge Fields
• Electric field compensation and sensing with a single ion in a planar trap