Trapped Ensembles of Ions or Atoms
ensemble quantum metrology
In so-called "ensemble quantum metrology" (in contrast to single-atom trapping), many atoms or ions in a macroscopic volume are thermally manipulated together (e.g. by laser cooling). The quantum states of the individual atoms or ions in an ensemble are usually not identical. After preparation, targeted quantum operations (e.g., by introducing laser pulses, magnetic fields, or microwaves) are performed on the ensemble to create a quantum superposition or entanglement between the atoms or ions. As a result, collective quantum mechanical effects (coherences) occur in the manipulated ensemble, e.g., "super radiant emissions."
Advantages:
- Easier to handle and control than individual quantum particles.
- Ensembles offer easier scalability compared to the above atomic or ion traps since many atoms or ions can be manipulated simultaneously.
Disadvantages:
- Due to interparticle interactions and other environmental effects, ensembles are more susceptible to decoherence and interference. This results in limited precision and sensitivity compared to single quantum particles.
Applications: Metrology, precision measurements (e.g., measurement of magnetic fields in geophysics and materials science), simple quantum information processing.
In cooperation with the Physikalisch-Technische Bundesanstalt and the Leibnitz Universität Hannover, the Institute for Experimental Quantum Metrology is developing a new and particularly compact linear ion trap, which can be integrated into a compact vacuum chamber. The aim is to use multi-ion spectroscopy in a commercial optical clock. Image by courtesy of Physikalisch-Technische Bundesanstalt, image has been taken from the article "ion traps for quantum simulations, quantum computers and metrology"