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Topological charge pumping with subwavelength Raman lattices



Ian Spielman, Gediminas Juzeliunas, Domantas Burba, mantas Raciunas


Recent experiments demonstrated deeply subwavelength lattices using atoms with $N$ internal states Raman-coupled with lasers of wavelength $\lambda$. The resulting unit cell was $\lambda/2N$ in extent, an $N$-fold reduction compared to the usual $\lambda/2$ periodicity of an optical lattice. For resonant Raman coupling, this lattice consists of $N$ independent sinusoidal potentials (with period $\lambda/2$) displaced by $\lambda/2N$ from each other. We show that detuning from Raman resonance induces tunneling between these potentials. Temporally modulating the detuning couples the $s$- and $p$-bands of the potentials, creating a pair of coupled subwavelength Rice--Mele chains. This operates as a novel topological charge pump that counter-intuitively can give half the displacement per pump cycle of each individual Rice--Mele chain separately. We analytically describe this behavior in terms of infinite-system Chern numbers, and numerically identify the associated finite-system edge states.
Physical Review A (Atomic, Molecular and Optical Physics)


Quantum geometry, topology, Quantum Hall, Bose-Einstein condensate


Spielman, I. , Juzeliunas, G. , Burba, D. and Raciunas, M. (2023), Topological charge pumping with subwavelength Raman lattices, Physical Review A (Atomic, Molecular and Optical Physics), [online],, (Accessed June 23, 2024)


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Created February 15, 2023