10 research outputs found
Measurement of the quadratic Zeeman shift of ^{85}Rb hyperfine sublevels using stimulated Raman transitions
We demonstrate a technique for directly measuring the quadratic Zeeman shift
using stimulated Raman transitions.The quadratic Zeeman shift has been measured
yielding [delta][nju] = 1296.8 +/-3.3 Hz/G^{2} for magnetically insensitive
sublevels (5S1/2, F = 2,mF = 0 -> 5S1/2, F = 3,mF = 0) of ^{85}Rb by
compensating the magnetic eld and cancelling the ac Stark shift. We also
measured the cancellation ratio of the differential ac Stark shift due to the
imbalanced Raman beams by using two pairs of Raman beams ([sigma]^{+},
[sigma]^{+}) and it is 1:3.67 when the one-photon detuning is 1.5 GHz in the
experiment
Comparative metabolomic analysis of exudates of microcystin-producing and microcystin-free Microcystis aeruginosa strains
Cyanobacterial harmful algal blooms (cHABs) dominated by Microcystis aeruginosa threaten the ecological integrity and beneficial uses of lakes globally. In addition to producing hepatotoxic microcystins (MC), M. aeruginosa exudates (MaE) contain various compounds with demonstrated toxicity to aquatic biota. Previously, we found that the ecotoxicity of MaE differed between MC-producing and MC-free strains at exponential (E-phase) and stationary (S-phase) growth phases. However, the components in these exudates and their specific harmful effects were unclear. In this study, we performed untargeted metabolomics based on liquid chromatography-mass spectrometry to reveal the constituents in MaE of a MC-producing and a MC-free strain at both E-phase and S-phase. A total of 409 metabolites were identified and quantified based on their relative abundance. These compounds included lipids, organoheterocyclic compounds, organic acid, benzenoids and organic oxygen compounds. Multivariate analysis revealed that strains and growth phases significantly influenced the metabolite profile. The MC-producing strain had greater total metabolites abundance than the MC-free strain at S-phase, whereas the MC-free strain released higher concentrations of benzenoids, lipids, organic oxygen, organic nitrogen and organoheterocyclic compounds than the MC-producing strain at E-phase. Total metabolites had higher abundance in S-phase than in E- phase in both strains. Analysis of differential metabolites (DMs) and pathways suggest that lipids metabolism and biosynthesis of secondary metabolites were more tightly coupled to growth phases than to strains. Abundance of some toxic lipids and benzenoids DMs were significantly higher in the MC-free strain than the MC-producing one. This study builds on the understanding of MaE chemicals and their biotoxicity, and adds to evidence that non-MC-producing strains of cyanobacteria may also pose a threat to ecosystem health
A Novel Monitoring Navigation Method for Cold Atom Interference Gyroscope
The implementation principle of a typical three-pulse cold atom interference gyroscope is introduced in this paper. Based on its configuration and current research status, the problems of cold atom interference gyro are pointed out. The data-rate is insufficient, and it is difficult to achieve high dynamic measurement. Then, based on these two limitations, a novel design of the monitoring navigation system of the cold atom interference gyroscope (CAIG) and an intermediate-grade inertial measurement unit (IMU) was proposed to obtain the long-term position result without GPS signals, such as the Inertial Navigation System (INS) in underwater vehicles. While the CAIG was used as the external gyro, the bias of IMU and the misalignment angle between the CAIG-frame and the IMU-frame are obtained through filtering technique. The simulation test and field test demonstrated the improvements of the long-term positioning accuracy of the INS
High fidelity entanglement of neutral atoms via a Rydberg-mediated single-modulated-pulse controlled-PHASE gate
Neutral atom platform has become an attractive choice to study the science of
quantum information and quantum simulation, where intense efforts have been
devoted to the entangling processes between individual atoms. For the
development of this area, two-qubit controlled-PHASE gate via Rydberg blockade
is one of the most essential elements. Recent theoretical studies have
suggested the advantages of introducing non-trivial waveform modulation into
the gate protocol, which is anticipated to improve its performance towards the
next stage. We report our recent experimental results in realizing a two-qubit
controlled-PHASE() gate via off-resonant modulated driving(ORMD) embedded
in two-photon transition for Rb atoms. It relies upon a single modulated
driving pulse with a carefully calculated smooth waveform to gain the
appropriate phase accumulations required by the two-qubit gate. Combining this
gate with global microwave pulses, two-atom entanglement is generated
with the raw fidelity of 0.945(6). Accounting for state preparation and
measurement (SPAM) errors, we extract the entanglement operation fidelity to be
0.980(7). Our work features completing the gate operation within a single
pulse to avoid shelved Rydberg population, thus demonstrate another promising
route for realizing high-fidelity two-qubit gate for neutral atom platform.Comment: 4 figure