Quantum nanofiber traps hold 4000 atoms, nearing blockade limit

Researchers are now stably trapping approximately 4000 cesium atoms using quantum nanofibers, approaching what is known as the collisional blockade regime and enabling more complex quantum systems. This achievement overcomes a key challenge in the field: efficiently loading atoms into traps a few orders of magnitude smaller than the wavelength of light. The team employed Λ-enhanced gray molasses (ΛGM) cooling, reaching temperatures of 1μK for cesium atom clouds and demonstrating a sixfold increase in trapped atoms compared to standard loading methods. This technique also extends atom storage time fivefold, even in very shallow traps with a depth of only 24μK. Maintaining atomic coherence within nanofiber-based traps is now demonstrably improved by a technique that preserves atom-photon coupling strength over extended storage times. Measurements reveal that the application of Λ-enhanced gray molasses (ΛGM) cooling prevents the heating of trapped cesium atoms, a phenomenon that degrades the interaction between the atoms and the guiding nanofiber. Without ΛGM cooling, the atom-photon coupling strength, β, steadily decreases…