Stopping an isolated metal ion

Question

If we obtain something like a single isolated hydrogen atom I.e. $H^+$ is it possible by keeping it in a system of charged rings to contain and stop it at the centre of the system?

Any positively charged ring would have electric field pointing towards its centre, if the ion tries to move then it will be pushed towards center! Clearly this would violate the uncertainity principle because we would know that the atom is at the Centre of the ring and is stopped, I think therefore it must have atleast some difficulty but I can't figure out why it may not be possible!

The question is that if it is possible, what does it say about the uncertainty priniciple and if it is not possible then why not?

Answer 1

The system you describe is called an ion trap and is used routinely to hold ions in place.

There's no violation of the uncertainty principle because the ion will have some zero point motion at the centre of the trap. The trap creates a potential well and the ion moves within this potential. To describe the ion we solve the Schrodinger equation for the ion in the potential well. This will give us some wavefunction that will have a non-zero energy in the ground state, just as we get for a particle in a box or a simple harmonic oscillator. The finite zero point energy means there will be an uncertainty in position.

Answer 2

I think the charge remains at the center. The reason why this situation is not violating the Uncertainty principle, is that the charge won't stop jiggling (even if you reduce the temperature to absolute zero). This solution also answers the question why atoms won't stop jiggling even at absolute zero. If they don't jiggle, it will violate Uncertainty principle.