5 research outputs found
A subwavelength atomic array switched by a single Rydberg atom
Enhancing light-matter coupling at the level of single quanta is essential
for numerous applications in quantum science. The cooperative optical response
of subwavelength atomic arrays was recently found to open new pathways for such
strong light-matter couplings, while simultaneously offering access to multiple
spatial modes of the light field. Efficient single-mode free-space coupling to
such arrays has been reported, but the spatial control over the modes of
outgoing light fields has remained elusive. Here we demonstrate such spatial
control over the optical response of an atomically thin mirror formed by a
subwavelength array of atoms in free space using a single controlled ancilla
atom excited to a Rydberg state. The switching behavior is controlled by the
admixture of a small Rydberg fraction to the atomic mirror, and consequently
strong dipolar Rydberg interactions with the ancilla. Driving Rabi oscillations
on the ancilla atom, we demonstrate coherent control of the transmission and
reflection of the array. Our results pave the way towards realizing novel
quantum coherent metasurfaces, creating controlled atom-photon entanglement and
deterministic engineering of quantum states of light.Comment: 8 pages, 5 figures + 9 pages Supplementary Informatio
Observation of brane parity order in programmable optical lattices
The Mott-insulating phase of the two-dimensional (2d) Bose-Hubbard model is
expected to be characterized by a non-local brane parity order. Parity order
captures the presence of microscopic particle-hole fluctuations and
entanglement, whose properties depend on the underlying lattice geometry. We
realize 2d Bose-Hubbard models in dynamically tunable lattice geometries, using
neutral atoms in a novel passively phase-stable tunable optical lattice in
combination with programmable site-blocking potentials. We benchmark the
performance of our system by single-particle quantum walks in the square,
triangular, kagome and Lieb lattice. In the strongly correlated regime, we
microscopically characterize the geometry dependence of the quantum
fluctuations and experimentally validate the brane parity as a proxy for the
non-local order parameter signaling the superfluid-to-Mott insulating phase
transition.Comment: Fixed typos and formattin
Quantum gas microscopy of Kardar-Parisi-Zhang superdiffusion
The Kardar-Parisi-Zhang (KPZ) universality class describes the coarse-grained
behavior of a wealth of classical stochastic models. Surprisingly, it was
recently conjectured to also describe spin transport in the one-dimensional
quantum Heisenberg model. We test this conjecture by experimentally probing
transport in a cold-atom quantum simulator via the relaxation of domain walls
in spin chains of up to 50 spins. We find that domain-wall relaxation is indeed
governed by the KPZ dynamical exponent , and that the occurrence of
KPZ scaling requires both integrability and a non-abelian SU(2) symmetry.
Finally, we leverage the single-spin-sensitive detection enabled by the
quantum-gas microscope to measure a novel observable based on spin-transport
statistics, which yields a clear signature of the non-linearity that is a
hallmark of KPZ universality.Comment: 8 pages, 5 figures + 13 pages Supplementary Informatio