Optimal Timing of Fungicide Application to Manage Fusarium Head Blight in Winter Barley.

Fusarium head blight (FHB) is among the chief threats to profitable barley production, and fungicide applications are one of two main strategies for reducing FHB damage to barley crops. However, there is very little published information on optimal timing of such applications. A 4-year field study was conducted with winter barley in Raleigh, North Carolina, to compare three timings for fungicide application: 50% spike emergence (Zadoks growth stage or GS 55), 100% spike emergence (GS 59), and 6 days after GS 59.

Jet Substructure in Fireworks Emission from Nonuniform and Rotating Bose-Einstein Condensates.

We show that jet emission from a Bose condensate with periodically driven interactions, also known as "Bose fireworks", contains essential information on the condensate wave function, which is difficult to obtain using standard detection methods. We illustrate the underlying physics with two examples. When condensates acquire phase patterns from external potentials or from vortices, the jets display novel substructure, such as oscillations or spirals, in their correlations.

Observation of Laughlin states made of light.

Much of the richness in nature emerges because simple constituents form an endless variety of ordered states. Whereas many such states are fully characterized by symmetries, interacting quantum systems can exhibit topological order and are instead characterized by intricate patterns of entanglement. A paradigmatic example of topological order is the Laughlin state, which minimizes the interaction energy of charged particles in a magnetic field and underlies the fractional quantum Hall effect.

Probing gravity by holding atoms for 20 seconds.

Atom interferometers are powerful tools for both measurements in fundamental physics and inertial sensing applications. Their performance, however, has been limited by the available interrogation time of freely falling atoms in a gravitational field. By suspending the spatially separated atomic wave packets in a lattice formed by the mode of an optical cavity, we realize an interrogation time of 20 seconds.

Development of 17 microsatellite markers in the federally endangered species (Asteraceae).

Premise: Microsatellite markers were developed in the federally endangered species (Asteraceae) to evaluate species boundaries with closely related congeners within the genus.

Methods And Results: Using Illumina data, 17 primer pairs were developed in populations of . The primers amplified motifs from tri- to hexanucleotide repeats with one to 17 alleles per locus.

Interacting Floquet polaritons.

Ordinarily, photons do not interact with one another. However, atoms can be used to mediate photonic interactions, raising the prospect of forming synthetic materials and quantum information systems from photons. One promising approach combines highly excited Rydberg atoms with the enhanced light-matter coupling of an optical cavity to convert photons into strongly interacting polaritons.

Correlations in high-harmonic generation of matter-wave jets revealed by pattern recognition.

Correlations in interacting many-body systems are key to the study of quantum matter. The complexity of the correlations typically grows quickly as the system evolves and thus presents a challenge for experimental characterization and intuitive understanding. In a strongly driven Bose-Einstein condensate, we observe the high-harmonic generation of matter-wave jets with complex correlations as a result of bosonic stimulation.

Density Waves and Jet Emission Asymmetry in Bose Fireworks.

A Bose condensate, subject to periodic modulation of the two-body interactions, was recently observed to emit matter-wave jets resembling fireworks [Nature (London) 551, 356 (2017)NATUAS0028-083610.1038/nature24272]. In this Letter, combining experiment with numerical simulation, we demonstrate that these "Bose fireworks" represent a late stage in a complex time evolution of the driven condensate.

Observation of Density-Dependent Gauge Fields in a Bose-Einstein Condensate Based on Micromotion Control in a Shaken Two-Dimensional Lattice.

We demonstrate a density-dependent gauge field, induced by atomic interactions, for quantum gases. The gauge field results from the synchronous coupling between the interactions and micromotion of the atoms in a modulated two-dimensional optical lattice. As a first step, we show that a coherent shaking of the lattice in two directions can couple the momentum and interactions of atoms and break the fourfold symmetry of the lattice.

Collective emission of matter-wave jets from driven Bose-Einstein condensates.

Scattering is used to probe matter and its interactions in all areas of physics. In ultracold atomic gases, control over pairwise interactions enables us to investigate scattering in quantum many-body systems. Previous experiments on colliding Bose-Einstein condensates have revealed matter-wave interference, haloes of scattered atoms, four-wave mixing and correlations between counter-propagating pairs.

Direct Lattice Shaking of Bose Condensates: Finite Momentum Superfluids.

We address band engineering in the presence of periodic driving by numerically shaking a lattice containing a bosonic condensate. By not restricting to simplified band structure models we are able to address arbitrary values of the shaking frequency, amplitude, and interaction strengths g. For "near-resonant" shaking frequencies with moderate g, a quantum phase transition to a finite momentum superfluid is obtained with Kibble-Zurek scaling and quantitative agreement with experiment.

Calibrating high intensity absorption imaging of ultracold atoms.

Absorption imaging of ultracold atoms is the foundation for quantitative extraction of information from experiments with ultracold atoms. Due to the limited exposure time available in these systems, the signal-to-noise ratio is largest for high intensity absorption imaging where the intensity of the imaging light is on the order of the saturation intensity. In this case, the absolute value of the intensity of the imaging light enters as an additional parameter making it more sensitive to systematic errors.

Universal space-time scaling symmetry in the dynamics of bosons across a quantum phase transition.

The dynamics of many-body systems spanning condensed matter, cosmology, and beyond are hypothesized to be universal when the systems cross continuous phase transitions. The universal dynamics are expected to satisfy a scaling symmetry of space and time with the crossing rate, inspired by the Kibble-Zurek mechanism. We test this symmetry based on Bose condensates in a shaken optical lattice.

Quantum Dynamics with Spatiotemporal Control of Interactions in a Stable Bose-Einstein Condensate.

Optical control of atomic interactions in quantum gases is a long-sought goal of cold atom research. Previous experiments have been hindered by rapid decay of the quantum gas and parasitic deformation of the trap potential. We develop and implement a generic scheme for optical control of Feshbach resonances which yields long quantum gas lifetimes and a negligible parasitic dipole force.

Roton-maxon excitation spectrum of Bose condensates in a shaken optical lattice.

We present experimental evidence showing that an interacting Bose condensate in a shaken optical lattice develops a roton-maxon excitation spectrum, a feature normally associated with superfluid helium. The roton-maxon feature originates from the double-well dispersion in the shaken lattice, and can be controlled by both the atomic interaction and the lattice modulation amplitude. We determine the excitation spectrum using Bragg spectroscopy and measure the critical velocity by dragging a weak speckle potential through the condensate-both techniques are based on a digital micromirror device.