Gray-Molasses Optical-Tweezer Loading: Controlling Collisions for Scaling Atom-Array Assembly

• Published in: Physical review. X Vol. 9; no. 1
• Main Authors: Brown, M. O., Thiele, T., Kiehl, C., Hsu, T.-W., Regal, C. A.
• Format: Journal Article
• Language: English
• Published: College Park American Physical Society 29.03.2019
• Subjects: Algorithms; Assembling; Assembly; Atomic collisions; Atomic properties; Efficiency; Fluorescence; Laser applications; Laser arrays; Laser cooling; Molasses; Neutral atoms; Quantum computing; Quantum theory; Qubits (quantum computing); Simulation; Stability; Syrups & sweeteners
• ISSN: 2160-3308; 2160-3308
• DOI: 10.1103/PhysRevX.9.011057

To isolate individual neutral atoms in microtraps, experimenters have long harnessed molecular photoassociation to make atom distributions sub-Poissonian. While a variety of approaches have used a combination of attractive (red-detuned) and repulsive (blue-detuned) molecular states, to date all experiments have been predicated on red-detuned cooling. In our work, we present a shifted perspective—namely, the efficient way to capture single atoms is to eliminate red-detuned light in the loading stage and use blue-detuned light that both cools the atoms and precisely controls trap loss through the amount of energy released during atom-atom collisions in the photoassociation process. Subsequent application of red-detuned light then assures the preparation of maximally one atom in the trap. UsingΛ-enhanced gray-molasses for loading, we study and model the molecular processes and find we can trap single atoms with 90% probability even in a very shallow optical tweezer. Using 100 traps loaded with 80% probability, we demonstrate one example of the power of enhanced loading by assembling a grid of 36 atoms using only a single move of rows and columns in 2D. Our insight is key in scaling the number of particles in a bottom-up quantum simulation and computation with atoms, or even molecules.