66 research outputs found
Integrable and Chaotic Dynamics of Spins Coupled to an Optical Cavity
We show that a class of random all-to-all spin models, realizable in systems of atoms coupled to an optical cavity, gives rise to a rich dynamical phase diagram due to the pairwise separable nature of the couplings. By controlling the experimental parameters, one can tune between integrable and chaotic dynamics on the one hand and between classical and quantum regimes on the other hand. For two special values of a spin-anisotropy parameter, the model exhibits rational Gaudin-type integrability, and it is characterized by an extensive set of spin-bilinear integrals of motion, independent of the spin size. More generically, we find a novel integrable structure with conserved charges that are not purely bilinear. Instead, they develop "dressing tails" of higher-body terms, reminiscent of the dressed local integrals of motion found in many-body localized phases. Surprisingly, this new type of integrable dynamics found in finite-size spin-1/2 systems disappears in the large-S limit, giving way to classical chaos. We identify parameter regimes for characterizing these different dynamical behaviors in realistic experiments, in view of the limitations set by cavity dissipation
Atom chip based generation of entanglement for quantum metrology
Atom chips provide a versatile `quantum laboratory on a microchip' for
experiments with ultracold atomic gases. They have been used in experiments on
diverse topics such as low-dimensional quantum gases, cavity quantum
electrodynamics, atom-surface interactions, and chip-based atomic clocks and
interferometers. A severe limitation of atom chips, however, is that techniques
to control atomic interactions and to generate entanglement have not been
experimentally available so far. Such techniques enable chip-based studies of
entangled many-body systems and are a key prerequisite for atom chip
applications in quantum simulations, quantum information processing, and
quantum metrology. Here we report experiments where we generate multi-particle
entanglement on an atom chip by controlling elastic collisional interactions
with a state-dependent potential. We employ this technique to generate
spin-squeezed states of a two-component Bose-Einstein condensate and show that
they are useful for quantum metrology. The observed 3.7 dB reduction in spin
noise combined with the spin coherence imply four-partite entanglement between
the condensate atoms and could be used to improve an interferometric
measurement by 2.5 dB over the standard quantum limit. Our data show good
agreement with a dynamical multi-mode simulation and allow us to reconstruct
the Wigner function of the spin-squeezed condensate. The techniques
demonstrated here could be directly applied in chip-based atomic clocks which
are currently being set up
Clinical overview and treatment options for non-skeletal manifestations of mucopolysaccharidosis type IVA
Phenotypic effects of concomitant insensitive acetylcholinesterase (ace-1 R ) and knockdown resistance (kdr R ) in Anopheles gambiae: a hindrance for insecticide resistance management for malaria vector control
Craniofacial vertical bone augmentation: A comparison between 3D printed monolithic monetite blocks and autologous onlay grafts in the rabbit
Seleção de traçadores para estudos de eficiência das aplicações de produtos fitossanitários
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