Cooling of trapped ions or charged particles close to the zero-point energy of motion allows exploration of quantum information science and fundamental physics. However, certain motional modes in trapped-ion crystals are difficult to cool due to their weak interaction with cooling radiation, typically laser beams, hampering progress in various applications. Here, we introduce a method to efficiently cool these challenging modes indirectly.
Our method involves transferring motional quanta from weakly cooled modes to strongly cooled modes, thus allowing indirect cooling of the former. The essential technique is fast population exchange between two involved modes realized by parametric modulation of the trapping potential that confines the ions. Remarkably, we demonstrate that even modes with nearly or exactly zero direct cooling rates can attain final motional occupations close to those for direct, strongly cooled modes using this indirect cooling technique.
This method can be applied to any Coulomb crystal containing both coolant ions and other charged species of interest. It enables efficient sympathetic cooling in trapped-ion quantum computing, a scenario where data qubits holding quantum information cannot be directly laser cooled. It also supports a wide range of charge-to-mass ratios in crystals with mixed species of ions, expanding possibilities for using various atomic, molecular, and mesoscopic species in quantum metrology and fundamental physics experiments.
Add Comment