Phys.org December 13, 2021
Most ions and other charged particles of spectroscopic interest lack the fast, cycling transitions that are necessary for direct laser cooling. In most cases, they can still be cooled sympathetically through their Coulomb interaction with a second, coolable ion species confined in the same potential. If the charge-to-mass ratios of the two ion types are too mismatched, the cooling of certain motional degrees of freedom becomes difficult. This limits both the achievable fidelity of quantum gates and the spectroscopic accuracy. Researchers in Germany developed algorithmic cooling protocol for transferring phonons from poorly to efficiently cooled modes. By combining laser cooling of coupled ions and quantum algorithm they were able to cool the highly charged ions down as far as 200 µK. The application of quantum algorithms ensured that ions that are too dissimilar for traditional laser cooling to work effectively could be cooled down together after all. Their work may make an optical atomic clock with highly charged ions possible. These findings are also of great significance for the development of quantum computers and for precision spectroscopy…read more. Open Access TECHNICAL ARTICLEÂ
Simplified depiction (not to scale) of the two-ion Coulomb crystal of a single Be+ion (red, left) and a single HCI (purple, right) confined in a linear Paul trap… Credit: Phys. Rev. X 11, 041049, 10 December 2021Â