Nanotrappy: An open-source versatile package for cold-atom trapping

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The LKB Quantum Network team, DAALI researchers at Sorbonne University, have developed Nanotrappy, a python package made for calculating optical trapping potentials for alkali atoms around nanostructures.

Trapping cold neutral atoms in close proximity to nanostructures has raised a large interest in recent years, pushing the frontiers of cavity-QED and boosting the emergence of the waveguide-QED field of research. The design of efficient dipole trapping schemes in evanescent fields is a crucial requirement and a difficult task. Here we present an open-source Python package for calculating optical trapping potentials for neutral atoms, especially in the vicinity of nanostructures.

Given field distributions and for a variety of trap configurations, nanotrappy computes the three-dimensional trapping potentials as well as the trap properties, ranging from trap positions to trap frequencies and state-dependent light shifts. We demonstrate the versatility for various seminal structures in the field, e.g., optical nanofiber, alligator slow-mode photonic-crystal waveguide, and microtoroid. This versatile package facilitates the systematic design of structures and provides a full characterization of trapping potentials with applications to the coherent manipulation of atoms and quantum information science.

Nanotrappy has been created to compute the light-shift potentials created by any combination of laser electric fields, with an emphasis on trapping atoms close to nanophotonic structures, as happens in the evanescent field. The package also includes user-friendly interactive tools for optimization and analysis of the trapping potentials.