Kylmäatomikello

Kylmäatomikello, or cold atom clock, is a type of atomic clock that utilizes ultra-cold atoms to achieve extremely high precision. These clocks work by interrogating the internal electronic transitions of atoms that have been cooled to temperatures near absolute zero. At these low temperatures, the atoms' motion is significantly reduced, minimizing Doppler shifts and other temperature-dependent errors that can affect the accuracy of atomic clocks operating at higher temperatures.

The cooling process typically involves laser cooling techniques, such as Doppler cooling and evaporative cooling, to trap and slow down the atoms. Once sufficiently cold, the atoms are placed in an optical lattice formed by intersecting laser beams. This lattice acts as a periodic potential that holds the atoms in place, further isolating them from external perturbations. A probe laser is then used to excite the atoms between two specific energy levels, which are defined by the atomic transition being used. The frequency of this probe laser is precisely controlled and locked to the atomic transition.

The stability and accuracy of a cold atom clock are determined by how well the probe laser's frequency can be stabilized to the atomic transition. The ultra-cold nature of the atoms allows for longer interrogation times and a narrower spectral line for the transition, leading to significantly improved frequency stability and reduced systematic uncertainties compared to traditional atomic clocks. These clocks are crucial for applications requiring the highest levels of timekeeping and frequency metrology, such as fundamental physics experiments, navigation systems, and scientific research.