Progress Towards a Spin-Specific Microwave Atom Chip Trap

We report on progress in the development of a spin-specific microwave atom chip trap based on the AC Zeeman (ACZ) effect. In this scheme, atoms are trapped in the minima of circularly polarized magnetic near-fields generated by AC currents in atom chip traces. ACZ potentials have applications in atom interferometry, quantum gates, and 1D many-body physics. Our proposed design utilizes multiple microstrip transmission lines to produce traps by overlapping the near-fields of neighboring microstrips. Axial confinement can be provided using a microwave lattice based on the ACZ or AC Stark effect. Ultimately, for an atom interferometer, precisely phase-controlled microwaves can control the axial position of the atoms in the lattice to increase interferometer arm separation or enclose an area. ACZ potentials are inherently spin-specific, able to trap any hyperfine magnetic state, and offer phase and detuning as parameters to control trap features. Additionally, potential roughness from chip wire defects is predicted to be suppressed compared to DC micro-magnetic chip traps. We investigate this in a two-wire configuration. To efficiently couple broadband microwaves onto the microstrip traces, we are developing an interface based on tapered coplanar waveguides. We present electromagnetic simulations of the microwave atom chip and interface designs.