Detection and Quantized Conductance of Neutral Atoms Near a Charged Carbon Nanotube

We describe a novel single atom detector that uses the high electric field surrounding a charged single-walled carbon nanotube to attract and subsequently field-ionize neutral atoms. A theoretical study of the field-ionization tunneling rates for atomic trajectories in the attractive potential near a nanowire shows that a broadly applicable, high spatial resolution, low-power, neutral-atom detector with nearly 100% efficiency is realizable with present-day technology. Calculations also show that the system can provide the first opportunity to study quantized conductance phenomena when detecting cold neutral atoms with mean velocities less than $15\mathrm{m}/\mathrm{s}$.

Figure 1

Schematic of experimental setup.

Figure 2

Calculated steps in the angular momentum quantum ladder. The nanotube diameter is 2 nm and the length is $5\mu \mathrm{m}$. Inset shows contribution from quantum tunneling of uncaptured atoms for a $1\mathrm{m}/\mathrm{s}$ atomic beam.

Figure 3

Ionization probability versus angular momentum and voltage for $1\mathrm{m}/\mathrm{s}$ rubidium atoms incident on a 2 nm diameter nanotube.