Coherent States for Trapped Ions: Applications in Quantum Optics and Precision Measurements

The evolution of squeezed coherent states of motion for trapped ions is investigated by applying the time-dependent variational principle for the Schrödinger equation. The method is applied in case of Paul and combined traps, for which the classical Hamiltonian and equations of motion are derived. Hence, coherent states provide a natural framework to: (a) engineer quantum correlated states for trapped ions intended for ultraprecise measurements, (b) explore the mechanisms responsible for decoherence, and (c) investigate the quantum–classical transition.