PHYSICS · Multi-part · Fermi University Physics · Quantum Mechanics · Quantum dynamics and its formulations · Quantum dynamics and its formulations
The Structure of Quantum Mechanics, Ch Slow change, sudden change and the Berry phase
Problem
A hydrogen atom's electron, initially in the ground state, is exposed to a rising external electric field from a terahertz pulse whose envelope rises over T=1.0ps. The peak field is weak enough that the energy shifts it produces stay small compared with the level gaps. The gap between the n=1 and n=2 hydrogen levels is ΔE=10.2eV.
((a)) Estimate the level-spacing time τ=ℏ/ΔE.
((b)) Decide, from the ratio T/τ, whether the electron can be expected to follow the instantaneous (field-dressed) ground state adiabatically.