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arXiv · 2003.06087

Protecting Spin Coherence in a Tunable Heisenberg Model

Emily J. Davis·Avikar Periwal·Eric S. Cooper·Gregory Bentsen·Simon J. Evered·Katherine Van Kirk·Monika H. Schleier-Smith
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Abstract

Using an ensemble of atoms in an optical cavity, we engineer a family of nonlocal Heisenberg Hamiltonians with continuously tunable anisotropy of the spin-spin couplings. We thus gain access to a rich phase diagram, including a paramagnetic-to-ferromagnetic Ising phase transition that manifests as a diverging magnetic susceptibility at the critical point. The susceptibility displays a symmetry between Ising interactions and XY (spin-exchange) interactions of the opposite sign, which is indicative of the spatially extended atomic system behaving as a single collective spin. Images of the magnetization dynamics show that spin-exchange interactions protect the coherence of the collective spin, even against inhomogeneous fields that completely dephase the non-interacting and Ising systems. Our results underscore prospects for harnessing spin-exchange interactions to enhance the robustness of spin squeezing protocols.

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Emily J. Davis, Avikar Periwal, Eric S. Cooper, Gregory Bentsen, Simon J. Evered, Katherine Van Kirk, Monika H. Schleier-Smith. 2020-08-30. Protecting Spin Coherence in a Tunable Heisenberg Model. https://doi.org/10.1103/physrevlett.125.060402

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