Two atoms reveal why tighter confinement is not always better
MIT’s lithium experiment tests the limits of orderly light scattering.
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Packing atoms closer together does not automatically make their light more orderly. An MIT study of lithium pairs exposes a limit to that intuition.[1]
In a November 10 preprint, not yet peer-reviewed, the researchers trapped atom pairs in a lattice made from light. They inferred a coherent fraction of 48% ± 4 percentage points under selected conditions. Here, coherent means elastic scattering with a definite phase relationship to the illuminating laser, not a quantum computer’s memory lifetime.[1]
The comparison: switching selected atoms into a weakly scattering state disrupted the array’s regular pattern, revealing the coherent contribution. The analysis corrected for those atoms’ remaining light scattering.[1]
The catch is that close neighbours interact through light. The accompanying calculations show their interaction can increase unwanted scattering; at still tighter confinement, opposing phases can cancel the coherent signal. Smaller is therefore not always better in this two-atom setting.[1]
It does not demonstrate a working quantum gate or establish a universal limit for larger atomic arrays.[1]