Integrated Atom Detector Based on Field Ionization near Carbon Nanotubes

TL;DR

This paper presents a novel atom detector utilizing field ionization near carbon nanotubes, achieving high field enhancement to ionize rubidium atoms rapidly, with potential applications in ultracold quantum gas measurements.

Contribution

The work introduces a new atom detector based on field ionization at carbon nanotube tips, demonstrating high field enhancement and ultrafast ionization suitable for quantum gas experiments.

Findings

Field enhancement up to 9x10^9 V/m at nanotube tips.

Atom ionization occurs within tens of nanometers from nanotube tips.

Ionization time scale is faster than 10^(-10) seconds.

Abstract

We demonstrate an atom detector based on field ionization and subsequent ion counting. We make use of field enhancement near tips of carbon nanotubes to reach extreme electrostatic field values of up to 9x10^9 V/m, which ionize ground state rubidium atoms. The detector is based on a carpet of multiwall carbon nanotubes grown on a substrate and used for field ionization, and a channel electron multiplier used for ion counting. We measure the field enhancement at the tips of carbon nanotubes by field emission of electrons. We demonstrate the operation of the field ionization detector by counting atoms from a thermal beam of a rubidium dispenser source. By measuring the ionization rate of rubidium as a function of the applied detector voltage we identify the field ionization distance, which is below a few tens of nanometers in front of nanotube tips. We deduce from the experimental data that field ionization of rubidium near nanotube tips takes place on a time scale faster than 10^(-10)s. This property is particularly interesting for the development of fast atom detectors suitable for measuring correlations in ultracold quantum gases. We also describe an application of the detector as partial pressure gauge.