Abstract
We present a method for preparing a single two-dimensional sample of a two-spin mixture of fermionic potassium in a single antinode of an optical lattice, in a quantum-gas microscope apparatus. Our technique relies on spatially-selective microwave transitions in a magnetic field gradient. Adiabatic transfer pulses were optimized for high efficiency and minimal atom loss and heating due to spin-changing collisions. We have measured the dynamics of those loss processes, which are more pronounced in the presence of a spin mixture. As the efficient preparation of atoms in a single antinode requires a homogeneous transverse magnetic field, we developed a method to image and minimize the magnetic field gradients in the focal plane of the microscope.
Highlights
The preparation and study of states of ultracold matter with low dimensionality is a fruitful area of research: these systems can exhibit unique properties, such as the Berezinskii–Kosterlitz–Thouless transition for a twodimensional (2D) gas [1, 2]; fermionic atoms in a 2D optical lattice realize the 2D Hubbard model, which is thought to contain the key mechanism to high-Tc superconductivity [3]
This demanding preparation can rely on a variety of techniques: they can combine magnetic and optical traps [17] to load a single antinode of a one-dimensional optical lattice; make use of blue-detuned, repulsive optical traps created by a spatial light modulator [18] or by using Laguerre–Gauss beams [19]
Other methods use an accordion optical lattice with adjustable spacing [20, 21], which allows for the compression of an initially large atomic sample into a single 2D system; or employ spatially-dependent microwave transitions in a magnetic gradient [4, 22] to isolate a single plane of a shortwavelength optical lattice
Summary
The preparation and study of states of ultracold matter with low dimensionality is a fruitful area of research: these systems can exhibit unique properties, such as the Berezinskii–Kosterlitz–Thouless transition for a twodimensional (2D) gas [1, 2]; fermionic atoms in a 2D optical lattice realize the 2D Hubbard model, which is thought to contain the key mechanism to high-Tc superconductivity [3]. Compared to the technique used in our previous publication [4], the scheme presented here introduces several new features, such as the simultaneous use of two spin states, the visualization of magnetic field gradients and the use of microwave transfers instead of optical pulses, whenever possible. We developed this scheme in order to minimize heating induced by photon scattering in the previously used technique [4], with the goal to increase the phase-space density, essential for the preparation of strongly-correlated fermionic phases.
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