Deterministic Fast Scrambling with Neutral Atom Arrays.

Fast scramblers are dynamical quantum systems that produce many-body entanglement on a timescale that grows logarithmically with the system size N. We propose and investigate a family of deterministic, fast scrambling quantum circuits realizable in near-term experiments with arrays of neutral atoms. We show that three experimental tools-nearest-neighbor Rydberg interactions, global single-qubit rotations, and shuffling operations facilitated by an auxiliary tweezer array-are sufficient to generate nonlocal interaction graphs capable of scrambling quantum information using only O(logN) parallel applications of nearest-neighbor gates. These tools enable direct experimental access to fast scrambling dynamics in a highly controlled and programmable way and can be harnessed to produce highly entangled states with varied applications.

Treelike Interactions and Fast Scrambling with Cold Atoms.

We propose an experimentally realizable quantum spin model that exhibits fast scrambling, based on nonlocal interactions that couple sites whose separation is a power of 2. By controlling the relative strengths of deterministic, nonrandom couplings, we can continuously tune from the linear geometry of a nearest-neighbor spin chain to an ultrametric geometry in which the effective distance between spins is governed by their positions on a tree graph. The transition in geometry can be observed in quench dynamics, and is furthermore manifest in calculations of the entanglement entropy. Between the linear and treelike regimes, we find a peak in entanglement and exponentially fast spreading of quantum information across the system. Our proposed implementation, harnessing photon-mediated interactions among cold atoms in an optical cavity, offers a test case for experimentally observing the emergent geometry of a quantum many-body system.

Novel Water-Soluble Bisphosphinite Chiral Ligands Derived from alpha,alpha- and beta,beta-Trehalose. Application to Asymmetric Hydrogenation of Dehydroamino Acids and Their Esters in Water or an Aqueous/Organic Biphasic Medium.

Novel 2,3:4,6-di-O-isopropylidene-alpha-D-glucopyranosyl-(1,1)-4,6-O-isopropylidene-2,3-di-O-diphenylphosphino-alpha-D-glucopyranoside (2), 2,3:4,6-di-O-cyclohexylidene-alpha-D-glucopyranosyl-(1,1)-4,6-O-cyclohexylidene-2,3-di-O-diphenylphosphino-alpha-D-glucopyranoside (4), and 2,3:4,6-di-O-cyclohexylidene-beta-D-glucopyranosyl-(1,1)-4,6-O-cyclohexylidene-2,3-di-O-diphenylphosphino-beta-D-glucopyranoside (11) were prepared from the corresponding alpha,alpha- or beta,beta-trehalose. The ligands were transformed into cationic Rh complexes, such as [Rh(alpha-D-glucopyranosyl-(1,1)-2,3-di-O-diphenylphosphino-alpha-D-glucopyranoside)(cod)]BF(4) (3) and [Rh(beta-D-glucopyranosyl-(1,1)-2,3-di-O-diphenylphosphino-beta-D-glucopyranoside)(cod)]BF(4) (12) bearing free hydroxy groups. These complexes were soluble in water and were efficient catalysts for the asymmetric hydrogenation of dehydroamino acids and their esters in water or an aqueous/organic biphasic medium with high enantioselectivity (up to 99.9% ee). Aqueous biphasic systems offer an easy separation of the aqueous catalyst phase from the product phase and allow recycling of the catalyst phase without the loss of enantioselectivity.