Scalable Multipartite Entanglement Created by Spin Exchange in an Optical Lattice.

Ultracold atoms in optical lattices form a competitive candidate for quantum computation owing to the excellent coherence properties, the highly parallel operations over spins, and the ultralow entropy achieved in qubit arrays. For this, a massive number of parallel entangled atom pairs have been realized in superlattices. However, the more formidable challenge is to scale up and detect multipartite entanglement, the basic resource for quantum computation, due to the lack of manipulations over local atomic spins in retroreflected bichromatic superlattices. In this Letter, we realize the functional building blocks in quantum-gate-based architecture by developing a cross-angle spin-dependent optical superlattice for implementing layers of quantum gates over moderately separated atoms incorporated with a quantum gas microscope for single-atom manipulation and detection. Bell states with a fidelity of 95.6(5)% and a lifetime of 2.20±0.13 s are prepared in parallel, and then connected to multipartite entangled states of one-dimensional ten-atom chains and two-dimensional plaquettes of 2×4 atoms. The multipartite entanglement is further verified with full bipartite nonseparability criteria. This offers a new platform toward scalable quantum computation and simulation.

Interrelated Thermalization and Quantum Criticality in a Lattice Gauge Simulator.

Gauge theory and thermalization are both topics of essential importance for modern quantum science and technology. The recently realized atomic quantum simulator for lattice gauge theories provides a unique opportunity for studying thermalization in gauge theory, in which theoretical studies have shown that quantum thermalization can signal the quantum phase transition. Nevertheless, the experimental study remains a challenge to accurately determine the critical point and controllably explore the thermalization dynamics due to the lack of techniques for locally manipulating and detecting matter and gauge fields. We report an experimental investigation of the quantum criticality in the lattice gauge theory from both equilibrium and nonequilibrium thermalization perspectives, with the help of the single-site addressing and atom-number-resolved detection capabilities. We accurately determine the quantum critical point and observe that the Néel state thermalizes only in the critical regime. This result manifests the interplay between quantum many-body scars, quantum criticality, and symmetry breaking.

Low-noise and high-power second harmonic generation of 532 nm laser for trapping ultracold atoms.

Optical lattices for coherently manipulating ultracold atoms demand high-power, low-noise, narrow-line-width, and continuous-wave lasers. Here, we report the implementation of a 30 W 532 nm low-noise laser by second harmonic generation from a 1064 nm fiber laser, which is capable to generate optical lattices for a quantum gas microscope of Rb87 atoms. The overall conversion efficiency is 59% at an input power of 51 W with a lithium triborate crystal coupled to a ring cavity. The relative intensity noise of the output laser is suppressed to -120 dBc/Hz in the range of 10 Hz-100 kHz with a high dynamic range of over 50 dB, which is suitable for long-term trapping and coherent manipulation of the quantum gases.

A compact gain-enhanced microwave helical antenna for 87Rb atomic experiments.

We present a compact and gain-enhanced microwave helical antenna for manipulating ultracold 87Rb atoms coherently. By replacing the reflecting plate with an enhancing cup, the voltage standing wave ratio is reduced by 0.5 in the frequency range of 6.73-6.93 GHz, which covers the resonant frequency between the ground-state hyperfine levels of the 87Rb atom. The gain of the helical antenna is increased by 1.25-1.63 dBi, whose length is 89 mm. Applying the antenna to ultracold 87Rb atomic experiments, we achieve a Rabi frequency of 60(1) ×2π kHz of the oscillation between the hyperfine levels.

Whole-Brain Volume CT Angiography can Effectively Detect Early Ischemic Cerebrovascular Diseases.

OBJECTIVE: To investigate the role of whole-brain volume computed tomography (CT) perfusion in assessing early ischemic cerebrovascular diseases. MATERIALS AND METHODS: Seventy-two patients with early ischemic cerebrovascular diseases who had undergone routine CT scan and 320-row volume CT whole-brain perfusion imaging within 8 h after admission were retrospectively enrolled in this one-center case-sectional study. The perfusion parameters of cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and dynamic CT angiogram (4D-CTA) were obtained and analyzed. RESULTS: Among 72 patients, 29 cases with 37 cerebral ischemic lesions were found in plain CT scan, whereas 51 cases with 76 lesions were found in whole-brain CT perfusion, with 30.6% more patients being detected. The CBF value was significantly lower in the abnormal than normal corresponding perfusion area in the healthy hemisphere (P<0.05), while the MTT and TTP values were significantly higher in the abnormal than the normal corresponding area (P<0.05). 4D-CTA image suggested that 59 cases had different degrees of stenosis or occlusion, including 11 mild, 18 moderate, 21 severe, and 9 occlusive cases. Four-D-CTA imaging could detect significantly (P<0.05) more patients with abnormal perfusion in severe cerebral vascular stenosis or occlusion than those with no, mild or moderate stenosis (93.33% vs. 16.67%) (P<0.05). The stenosis of intracranial and carotid arteries was positively correlated with MTT and TTP values (P<0.05). CONCLUSION: Whole-brain volume CT angiography can comprehensively display early cerebral ischemic lesions, cerebral blood perfusion status, and cerebral vascular stenosis, providing valuable information for early detection of ischemic cerebral diseases and appropriate treatment planning.

A high-power and low-noise 532-nm continuous-wave laser for quantum gas microscopy.

Low-noise, high-power 532-nm lasers are of great interest in many scientific research studies, such as gravitational wave detection and ultracold atom experiments. In particular, in the experiments of quantum gas microscopy, a large power of laser is necessary during the imaging process, while low noise is important for preventing the atoms from being heated up. In this work, we report on the generation of such a 532-nm continuous-wave laser by coherently combining two laser beams produced by single-pass second-harmonic generation. The power of the combined laser is up to 17 W. With the help of intensity stabilization, we are able to suppress the relative intensity noise to below -120 dBc/Hz. The generated laser satisfies the experimental requirements for integrating optical superlattices with a quantum gas microscope.

The Application of Computed Tomography Perfusion in the Alberta Stroke Program Early Computed Tomography Score for Endovascular Treatment of Acute Ischemic Stroke in the Anterior Circulation.

OBJECTIVE: The present study investigated the predictive value of each perfusion parameter of the Alberta Stroke Program Early Computed Tomography Score (ASPECTS) in CT perfusion (CTP) imaging for the prognosis of endovascular treatment at the time of admission in patients with acute ischemic stroke in the anterior circulation. PATIENTS AND METHODS: The imaging data of 62 patients with acute ischemic stroke in the anterior circulation with an onset time of 6 h or less were retrospectively analyzed. All patients underwent the one-stop whole-brain dynamic volume four-dimensional (4D) CT angiography (CTA)-CTP and cranial magnetic resonance imaging (MRI) within seven days after treatment. The patients were divided into better and worse prognosis groups according to their clinical symptoms, combined with an MRI-ASPECTS score of ≤ 6 within seven days after treatment. The observed perfusion parameters included cerebral blood flow (CBF)-ASPECTS, cerebral blood volume (CBV)-ASPECTS, mean transit time (MTT)-ASPECTS, and time to peak (TTP)-ASPECTS. The difference in ASPECTS scores involving the CTP parameter, as well as diagnostic power, was compared between the two groups of patients. RESULTS: All CTP-ASPECTS scores negatively correlated with clinical prognosis. The higher the CTP-ASPECTS scores preceding treatment in patients with ischemic stroke in the anterior circulation, the better the prognosis. There were statistically significant differences in the scores of CBF-ASPECTS and CBV-ASPECTS between the two groups (P < 0.05). Receiver operating curve (ROC) analysis showed that the parameter with the largest area under the curve (AUC) was the CBF-ASPECTS score (P = 0.003), with a sensitivity of 90.9%, a specificity of 59.1%, and an AUC of 0.806, which was the most valuable prognostic predictor. CONCLUSION: The CBF-ASPECTS score presented significant value as a primary indicator for predicting the outcome of endovascular treatment in patients with acute ischemic stroke in the anterior circulation, and it had good application prospects in clinical practice.

High-powered optical superlattice with robust phase stability for quantum gas microscopy.

Optical superlattice has a wide range of applications in the study of ultracold atom physics. Especially, it can be used to trap and manipulate thousands of atom pairs in parallel which constitutes a promising system for quantum simulation and quantum computation. In the present work, we report on a high-power optical superlattice formed by a 532-nm and 1064-nm dual-wavelength interferometer with a short lattice spacing of 630 nm. The short-term fluctuation (in 10 seconds) of the relative phase between the short lattice and the long lattice is measured to be 0.003π, which satisfies the needs for performing two-qubit gates among neighboring lattice sites. We further implement this superlattice in a 87Rb experiment with a quantum gas microscope of single-site resolution, where the high-power 532-nm laser is necessary for pinning atoms in the short lattice during imaging, providing a unique platform for engineering quantum states.

Ultra-low noise and high bandwidth bipolar current driver for precise magnetic field control.

Current sources with extremely low noise are significant for many branches of scientific research, such as experiments of ultra-cold atoms, superconducting quantum computing, and precision measurements. Here we construct and characterize an analog-controlled bipolar current source with high bandwidth and ultra-low noise. A precise and stable resistor is connected in series with the output for current sensing. After being amplified with an instrumentation amplifier, the current sensing signal is compared with an ultra-low noise reference, and proportional-integral (PI) calculations are performed via a zero-drift low-noise operational amplifier. The result of the PI calculation is sent to the output power operational amplifier for closed-loop control of the output current. In this way, a current of up to 16 A can be sourced to or sunk from a load with a compliance voltage of greater than ±12 V. The broadband current noise of our bipolar current source is about 0.5 µA/Hz and 1/f corner frequency is less than 1 Hz. Applications of this current source in a cold atom interferometer, as well as active compensation of a stray magnetic field, are presented. A method for measuring high-frequency current noise in a 10 A DC current with a sensitivity down to a level of 10 µA is also described.

Fluorescent conjugated microporous polymer based on perylene tetraanhydride bisimide for sensing o-nitrophenol.

A novel conjugated microporous polymer based on perylene tetraanhydride bisimide (DP2A2) has been synthesized through Sonogashira-Hagihara cross-coupling polymerization of tetrabromo-substituted perylene tetraanhydride bisimide derivative (DPBr2ABr2) with 1,4-diethynylbenzene, whose Brunauer-Emmett-Teller (BET) specific surface area is about 378 m2 g-1. The fluorescence quenching behaviors of the DP2A2 were investigated. It is found that the DP2A2 shows high sensitivity and selectivity to tracing o-nitrophenol (o-NP) in THF with KsV constant of 2.00 × 104 L mol-1. The detection limit (LOD) is 1.50 × 10-9 mol L-1. The possible sensing mechanism for the luminescent quenching of DP2A2 towards o-NP exciting at 365 nm was considered the donor-acceptor electron transfer mechanism, which is a combined result from both dynamic (collisional) and static quenching. Moreover, the static quenching process is dominant for DP2A2.

Combination of hearing screening and genetic screening for deafness-susceptibility genes in newborns.

The aim of this study was to determine the clinical significance of the results of screening of newborn hearing and the incidence of deafness-susceptibility genes. One thousand newborn babies in the Handan Center Hospital (Handan, China) underwent screening of hearing and deafness-susceptibility genes. The first screening test was carried out using otoacoustic emissions (OAEs). Babies with hearing loss who failed to pass the initial screening were scheduled for rescreening at 42 days after birth. Cord blood was used for the screening of deafness-susceptibility genes, namely the GJB2, SLC26A4 and mitochondrial 12S rRNA (MTRNR1) genes. Among the 1,000 neonates that underwent the first hearing screening, 25 exhibited left-sided hearing loss, 21 exhibited right-sided hearing loss and 15 cases had binaural hearing loss. After rescreening 42 days later, only one of the initial 61 cases exhibited hearing loss under OAE testing. The neonatal deafness gene tests showed two cases with 1555A>G mutation and two cases with 1494C>T mutation of the MTRNR1 gene. In the SLC26A4 gene screening, four cases exhibited the heterozygous IVS7-2A>G mutation and one case exhibited heterozygous 1226G>A mutation. In the GJB2 gene screening, two cases exhibited the homozygous 427C>T mutation and 10 exhibited the heterozygous 235delC mutation. The genetic screening revealed 21 newborns with mutations in the three deafness-susceptibility genes. The overall carrier rate was 2.1% (21/1,000). The association of hearing and gene screening may be the promising screening strategy for the diagnosis of hearing loss.