Search for: All records

Vogelet al.reveals the stereochemical basis of alternative substrate cleavage byS. pyogenesSrtA for ligands with a P1′ Leu residue. The substrate adopts puckered alternative binding, whereby cleavage occurs between the P1′ and P2′ positions.

 

In situ tunable photonic filters and memories are important for emerging quantum and classical optics technologies. However, most photonic devices have fixed resonances and bandwidths determined at the time of fabrication. Here we present an in situ tunable optical resonator on thin-film lithium niobate. By leveraging the linear electro-optic effect, we demonstrate widely tunable control over resonator frequency and bandwidth on two different devices. We observe up to ∼50 × tuning in the bandwidth over ∼50 V with linear frequency control of ∼230 MHz/V. We also develop a closed-form model predicting the tuning behavior of the device. This paves the way for rapid phase and amplitude control over light transmitted through our device.

 

The organic salt ( S )-nicotinium 2,6-dihydroxybenzoate undergoes reversible single crystal to single crystal phase transition at 104 K. The phase transition was monitored using temperature dependent single crystal X-ray diffraction and was attributed to symmetry breaking translations and rotations of the crystal components. 

Interstellar small bodies are unique probes into the histories of exoplanetary systems. One hypothesized class of interlopers are “Jurads,” exocomets released into the Milky Way during the post-main-sequence as the thermally pulsing asymptotic giant branch (AGB) host stars lose mass. In this study, we assess the prospects for the Legacy Survey of Space and Time (LSST) to detect a Jurad and examine whether such an interloper would be observationally distinguishable from exocomets ejected during the (pre-)main-sequence. Using analytic and numerical methods, we estimate the fraction of exo–Oort Cloud objects that are released from 1–8M_⊙stars during post-main-sequence evolution. We quantify the extent to which small bodies are altered by the increased luminosity and stellar outflows during the AGB, finding that some Jurads may lack hypervolatiles and that stellar winds could deposit dust that covers the entire exocomet surface. Next, we construct models of the interstellar small body reservoir for various size–frequency distributions and examine the LSST’s ability to detect members of those hypothesized populations. Combining these analyses, we highlight the joint constraints that the LSST will place on power-law size–frequency distribution slopes, characteristic sizes, and the total mass sequestered in the minor planets of exo–Oort Clouds. Even with the LSST’s increased search volume compared to contemporary surveys, we find that detecting a Jurad is unlikely but not infeasible given the current understanding of (exo)planet formation.

 

The quantum noise of light, attributed to the random arrival time of photons from a coherent light source, fundamentally limits optical phase sensors. An engineered source of squeezed states suppresses this noise and allows phase detection sensitivity beyond the quantum noise limit (QNL). We need ways to use quantum light within deployable quantum sensors. Here we present a photonic integrated circuit in thin-film lithium niobate that meets these requirements. We use the second-order nonlinearity to produce a squeezed state at the same frequency as the pump light and realize circuit control and sensing with electro-optics. Using 26.2 milliwatts of optical power, we measure (2.7 ± 0.2)% squeezing and apply it to increase the signal-to-noise ratio of phase measurement. We anticipate that photonic systems like this, which operate with low power and integrate all of the needed functionality on a single die, will open new opportunities for quantum optical sensing.

 

In the title double proton-transfer salt, C 12 H 12 N 2 2+ ·2C 8 H 7 O 4 − , consisting of a 1:2 ratio of 4,4'-(ethene-1,2-diyl)dipyridinium cations ( trans bipyridinium ethylene) to 2-hydroxy-3-methoxybenzoate anions ( o -vanillate), the complete cation is generated by crystallographic inversion symmetry and it is linked to adjacent o -vanillate anions by N—H...O hydrogen bonds, forming trimolecular assemblies. The trimers are linked by C—H...O hydrogen bonds as well as aromatic π–π stacking interactions into a three-dimensional network. The anion features an intramolecular O—H...O hydrogen bond.