Realizing Synthetic Dimensions and Artificial Magnetic Flux in a Trapped-Ion Quantum Simulator

Synthetic dimension is a potent tool in quantum simulation of topological phases of matter. Here we propose and demonstrate a scheme to simulate an anisotropic Harper-Hofstadter model with controllable magnetic flux on a two-leg ladder using the spin and motional states of a single trapped ion. We verify the successful simulation of this model by comparing the measured dynamics with theoretical predictions under various coupling strength and magnetic flux, and we observe the chiral motion of wave packets on the ladder as evidence of the topological chiral edge modes. We develop a quench path to adiabatically prepare the ground states for varying magnetic flux and coupling strength, and we measure the chiral current on the ladder for the prepared ground states, which allows us to probe the quantum phase transition between the Meissner phase and the vortex phase. Our work demonstrates the trapped ion as a powerful quantum simulation platform for topological quantum matter.

Realization of a crosstalk-avoided quantum network node using dual-type qubits of the same ion species

Generating ion-photon entanglement is a crucial step for scalable trapped-ion quantum networks. To avoid the crosstalk on memory qubits carrying quantum information, it is common to use a different ion species for ion-photon entanglement generation such that the scattered photons are far off-resonant for the memory qubits. However, such a dual-species scheme can be subject to inefficient sympathetic cooling due to the mass mismatch of the ions. Here we demonstrate a trapped-ion quantum network node in the dual-type qubit scheme where two types of qubits are encoded in the S and F hyperfine structure levels of 171Yb+ ions. We generate ion photon entanglement for the S-qubit in a typical timescale of hundreds of milliseconds, and verify its small crosstalk on a nearby F-qubit with coherence time above seconds. Our work demonstrates an enabling function of the dual-type qubit scheme for scalable quantum networks.

[Analysis of factors affecting the quality of donor corneal endothelial cells]

Objective: To explore the factors influencing the quality of donor corneal endothelium. Methods: A retrospective case series study was conducted. Data from 568 donor corneas obtained from the Shandong Eye Bank between July 1, 2020, and June 30, 2021, were collected for analysis. The corneal endothelium of the donor corneas was observed using corneal endothelial microscopy to assess corneal endothelial cell density (ECD), coefficient of variation, and hexagonal cell ratio (HEX). Relevant factors of corneal donors were collected, including gender, age, cause of death, season of death, time from death to corneal retrieval, and methods of corpse preservation, to investigate their impact on the quality of donor corneal endothelium. The age factor was divided into five age groups: 0-20 years, 21-40 years, 41-60 years, 61-80 years, and >80 years. The time of corneal retrieval was divided into three periods based on the time elapsed since the donor's death: <6 hours, 6-12 hours, and >12 hours. The relationship between these factors and corneal endothelial conditions was analyzed. Results: The 568 donor corneas were obtained from 288 donors, including 225 males (78.13%) and 63 females (21.87%). The mean age was 51.77±18.48 years. The causes of death among donors were as follows: cardiovascular diseases 54.58% (275 individuals), cancer 17.96% (74 individuals), organ failure 14.26% (49 individuals), and accidents 13.20% (64 individuals). The mean time of corneal retrieval after donor death was 140 (76, 400) minutes (ranging from 30 minutes to 45 hours). Among the 145 corneas (25.53%) that had their initial corneal endothelial microscopy examination, the images were not clear, and after thorough rewarming, 106 corneas (18.7%) still had unclear images and could not be analyzed. Among the 462 corneas (81.3%) with clear images, the ECD was (2 602.23±318.40) cells/mm², the coefficient of variation was 36.61%±4.81%, and the HEX was 52.73%±7.15%. The ECD of corneas from older donors was lower compared to younger donors, and the differences between age groups were statistically significant (P<0.001). Corneas from donors who died due to accidents had a higher ECD [(2 829.88±313.90) cells/mm²] compared to those who died from cancer, cardiovascular diseases, and organ failure, and the differences were statistically significant (P<0.001). The ECD was highest when corneas were retrieved within 6 hours after death, and the difference was statistically significant (P<0.001). Older donors had higher coefficients of variation but lower HEX values (both P<0.05). Corneas retrieved after a longer time from death had higher coefficients of variation, and the difference was statistically significant (P<0.05), but there was no statistically significant difference in HEX (P>0.05). Organ failure, cryopreservation, and corneal retrieval time >12 hours were risk factors for unclear corneal endothelial imaging (all P<0.001). Among the 136 corneal endothelial images (23.94%), circular, oval, or band-shaped dark areas were observed, and corneas with dark areas had lower ECD (P<0.05). The longer the time elapsed from death to corneal retrieval, the more dark areas were observed (P<0.001). The presence of dark areas did not affect the coefficient of variation and HEX (P>0.05). Conclusion: Advanced donor age, death due to chronic diseases, longer time elapsed from death to corneal retrieval, and cryopreservation of the body lead to a decrease in the quality of donor corneal endothelium.

Probing Complex-Energy Topology via Non-Hermitian Absorption Spectroscopy in a Trapped Ion Simulator

Non-Hermitian systems generically have complex energies, which may host topological structures, such as links or knots. While there has been great progress in experimentally engineering non-Hermitian models in quantum simulators, it remains a significant challenge to experimentally probe complex energies in these systems, thereby making it difficult to directly diagnose complex-energy topology. Here, we experimentally realize a two-band non-Hermitian model with a single trapped ion whose complex eigenenergies exhibit the unlink, unknot, or Hopf link topological structures. Based on non-Hermitian absorption spectroscopy, we couple one system level to an auxiliary level through a laser beam and then experimentally measure the population of the ion on the auxiliary level after a long period of time. Complex eigenenergies are then extracted, illustrating the unlink, unknot, or Hopf link topological structure. Our work demonstrates that complex energies can be experimentally measured in quantum simulators via non-Hermitian absorption spectroscopy, thereby opening the door for exploring various complex-energy properties in non-Hermitian quantum systems, such as trapped ions, cold atoms, superconducting circuits, or solid-state spin systems.

Evaluation of the role of 8-iso-PGF levels at multiple sites during intracranial hemorrhage in pediatric patients

OBJECTIVE

The present study was planned to explore the role of 8-isomeric-prostaglandinF2α (8-iso-PGF2α) levels at the multiple sites of cerebrospinal fluid in children with intracranial hemorrhage.

PATIENTS AND METHODS

90 children with intracranial hemorrhage were admitted to Surgery Intensive Care Unit (SICU) of our hospital from January to December 2013 and were selected as study subjects. They were divided into group A (n=30), group B (n=30) and group C (n=30). The group A was given conventional treatment, the group B was treated with minimally invasive puncture and the group C was treated with cerebrospinal fluid decompression. After 1 d, 2 d, 3 d, and 7 d of hospitalization, enzyme-linked immunosorbent assay (ELISA) was used to detect the 8-iso-PGF2α levels in peripheral blood of children in all groups. On the day of admission and 10 d after treatment, 3 groups of children were implemented with brain nuclear magnetic resonance spectroscopy for metabolite analyses.

RESULTS

On the day of admission there were no significant differences in the 8-iso-PGF2α levels among group A, B and C. Further, after 1 d, 3 d, 7 d of hospital stay, the 8-iso-PGF2α levels in peripheral blood showed a gradual downward trend, and decline range of the group C was greater than that of group A and B (p < 0.05). After 10 days of treatment, there were significant differences in the bilateral temporal lobe and hippocampal NAA/Creatinine (Cr), Cho/Cr, mI/Cr and NAA/mI among group A, B, and C. The survival rate of group C was higher than that of group A and B (p < 0.05). On the other hand, the prevalence of sequelae was significantly lower than that of group A and B (p < 0.05). The amount of blood loss in children with intracranial hemorrhage was positively correlated with the levels of 8-iso-PGF2α in peripheral blood (r = 0.546, p < 0.05) as observed by Spearman correlation analysis.

CONCLUSIONS

8-iso-PGF2α plays an important role in the pathogenesis of intracranial hemorrhage, and could be utilized as a biomarker of oxidative stress in children with intracranial hemorrhage. Further, cerebrospinal fluid decompression is a better method of treatment for intracranial hemorrhage.

[Association of sleep quality with hypertension in the elderly of Jino nationality: a multilevel model analysis]

Objective: To evaluate the association of sleep quality with hypertension in the elderly population aged 60 years and older of Jino nationality. Methods: In August 2015, a cross-sectional population-based survey was conducted to investigate the prevalence of hypertension in 805 subjects sampled by multistage stratified and cluster sampling from the elderly population of Jino nationality, the sleep quality was assessed by the Pittsburgh Sleep Quality Index (PSQI, a poor sleep group was defined as having a global PSQI score>7, a good sleep group was with a score of 7 or less), and the multilevel Logistic regression model was applied to analyze the association of sleep quality with hypertension. Results: A total of 793 eligible participants were available for analysis. Overall, 118 participants (14.9%) were in the poor sleep group, and 675 participants (85.1%) were in the good sleep group. The prevalence of hypertension, prevalence of isolated systolic hypertension, average systolic blood pressure (SBP) and diastolic blood pressure (DBP) of the poor sleep group were significantly high than those of the good sleep group[73.7%, 22.0%, (139.2±17.7) and (82.5±10.6) mmHg (1 mmHg=0.133 kPa) vs 33.0%, 9.0%, (131.2±15.0) and (78.5±8.9) mmHg, all P<0.05]. The results of covariate-adjusted multilevel Logistic regression model indicated that subjective sleep quality (OR=2.64, 95% CI: 1.08-6.44), sleep latency (OR=2.98, 95% CI: 1.52-5.86), sleep disturbance (OR=2.93, 95% CI: 1.06-8.10), daytime dysfunction (OR=3.86, 95% CI: 1.74-8.58) and poor sleep (OR=3.98, 95% CI: 2.05-7.73) had the positive correlation with hypertension. Conclusions: The elderly population of Jino nationality with poor sleep have high SBP and DBP. There are positive associations of PSQI and its components with hypertension in the elderly population of Jino nationality.