Ancestry analysis using a self-developed 56 AIM-InDel loci and machine learning methods.

Insertion/deletion (InDel) polymorphisms can be used as one of the ancestry-informative markers in ancestry analysis. In this study, a self-developed panel consisting of 56 ancestry-informative InDels was used to investigate the genetic structures and genetic relationships between Chinese Inner Mongolia Manchu group and 26 reference populations. The Inner Mongolia Manchu group was closely related in genetic background to East Asian populations, especially the Han Chinese in Beijing. Moreover, populations from northern and southern East Asia displayed obvious variations in ancestral components, suggesting the potential value of this panel in distinguishing the populations from northern and southern East Asia. Subsequently, four machine learning models were performed based on the 56 AIM-InDel loci to evaluate the performance of this panel in ancestry prediction. The random forest model presented better performance in ancestry prediction, with 91.87% and 99.73% accuracy for the five and three continental populations, respectively. The individuals of the Inner Mongolia Manchu group were assigned to the East Asian populations by the random forest model, and they exhibited closer genetic affinities with northern East Asian populations. Furthermore, the random forest model distinguished 87.18% of the Inner Mongolia Manchus from the East Asian populations, suggesting that the random forest model based on the 56 ancestry-informative InDels could be a potential tool for ancestry analysis.

Acoustic and Text Features Analysis for Adult ADHD Screening: A Data-Driven Approach Utilizing DIVA Interview.

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder commonly seen in childhood that leads to behavioural changes in social development and communication patterns, often continues into undiagnosed adulthood due to a global shortage of psychiatrists, resulting in delayed diagnoses with lasting consequences on individual's well-being and the societal impact. Recently, machine learning methodologies have been incorporated into healthcare systems to facilitate the diagnosis and enhance the potential prediction of treatment outcomes for mental health conditions. In ADHD detection, the previous research focused on utilizing functional magnetic resonance imaging (fMRI) or Electroencephalography (EEG) signals, which require costly equipment and trained personnel for data collection. In recent years, speech and text modalities have garnered increasing attention due to their cost-effectiveness and non-wearable sensing in data collection. In this research, conducted in collaboration with the Cumbria, Northumberland, Tyne and Wear NHS Foundation Trust, we gathered audio data from both ADHD patients and normal controls based on the clinically popular Diagnostic Interview for ADHD in adults (DIVA). Subsequently, we transformed the speech data into text modalities through the utilization of the Google Cloud Speech API. We extracted both acoustic and text features from the data, encompassing traditional acoustic features (e.g., MFCC), specialized feature sets (e.g., eGeMAPS), as well as deep-learned linguistic and semantic features derived from pre-trained deep learning models. These features are employed in conjunction with a support vector machine for ADHD classification, yielding promising outcomes in the utilization of audio and text data for effective adult ADHD screening. Clinical impact: This research introduces a transformative approach in ADHD diagnosis, employing speech and text analysis to facilitate early and more accessible detection, particularly beneficial in areas with limited psychiatric resources. Clinical and Translational Impact Statement: The successful application of machine learning techniques in analyzing audio and text data for ADHD screening represents a significant advancement in mental health diagnostics, paving the way for its integration into clinical settings and potentially improving patient outcomes on a broader scale.

Effects of intravenous rtPA in patients with minor stroke.

BACKGROUND: Whether minor ischemic stroke (MIS) patients can benefit from intravenous thrombolysis (IVT) remains controversial. The association between the efficacy of IVT and baseline National Institute of Health Stroke Scale (NIHSS) score is unclear in MIS, while the association in moderate and severe stroke is known. This study aimed to explore the effect of IVT in patients with MIS and analyze its efficacy in patients with different baseline NIHSS scores. METHODS: Patients with a NIHSS score ≤5 within 4.5 h of stroke onset were screened in 32 centers. Patients with and without IVT were matched to a ratio of 1:1 with propensity scores. An excellent outcome was defined as a modified Rankin Scale (mRS) score ≤1 at three months after stroke onset. Safety outcomes included mortality and symptomatic intracranial hemorrhage (sICH). Multivariate analysis was used to compute the adjusted odds ratio (OR) for excellent outcomes. The effect of IVT was further analyzed in subgroups according to the baseline NIHSS score. RESULTS: Of the 23,853 screened, 3336 patients with MIS who arrived at the hospital within 4.5 h of onset were included. The 1163 patients treated with IVT were matched with 1163 patients without IVT. IVT in minor strokes generated an adjusted OR of 1.38 (95% CI: 1.09-1.75, p = 0.009) for excellent outcomes. There were no significant differences in mortality (0.17% vs. 0.09%, p = 1.000) and sICH (0.69% vs. 0.86%, p = 0.813) between patients with and without IVT. Subgroup analysis showed that there was no significant effect of IVT in the baseline NIHSS 0-1 or 2-3 subgroups, with adjusted OR of 0.816 (95% CI 0.437-1.53, p = 0.525) and1.22 (95% CI 0.845-1.77, p = 0.287), respectively. In patients with NIHSS score of 4-5, IVT was significantly effective, with an adjusted OR of 1.53 (95% CI 1.02-2.30, p = 0.038). CONCLUSION: IVT can improve MIS outcomes. The risks of sICH and mortality did not increase, especially in patients with NIHSS scores 4 to 5, who could benefit from IVT significantly.

Overall, intravenous thrombolysis can improve the outcomes of patients with minor stroke.Minor stroke patients with a baseline NIHSS score of 4-5 can benefit the most from intravenous thrombolysis.

Using two self-developed InDel panels to explore forensic traits and ancestral components in the Hui group.

To address the challenges faced by forensic examiners in degraded DNA analysis, we have developed two different panels for various forensic applications, encompassing an AIM-InDel panel for ancestry inference and a Multi-InDel panel for individual identification, respectively. Herein, the efficiencies of these two panels were tested in the Chinese Hui group. By calculating forensic parameters and simulating family relationships, we verified that the Multi-InDel panel could be an effective tool for individual identification, paternity testing, and could assist in kinship identification in the Hui group. For full siblings, the true positive rate of kinship discrimination was 96.553%, when the threshold of log10LR was 1. The cumulative probability of matching as well as cumulative probability of exclusion were 3.8117 × 10-26 and 0.999999722, respectively. Meanwhile, we found that the AIM-InDel panel was effective for bio-geographic ancestry inference, with the vast majority of loci contributing significantly to distinguish East Asian, African, and European populations. By studying the population structure of the Hui ethnic minority, the genetic distance to the Beijing Han population was the closest among the 26 reference populations, which was similar to previous reports. In summary, we have developed two panels which can be effectively applied to the Hui group for individual identification, parentage testing and bio-geographic ancestry inference.

Ancestral Information Analysis of Chinese Korean Ethnic Group via a Novel Multiplex DIP System.

Deletion/insertion polymorphism (DIP) is one of the more promising genetic markers in the field of forensic genetics for personal identification and biogeographic ancestry inference. In this research, we used an in-house developed ancestry-informative marker-DIP system, including 56 autosomal diallelic DIPs, three Y-chromosomal DIPs, and an Amelogenin gene, to analyze the genetic polymorphism and ancestral composition of the Chinese Korean group, as well as to explore its genetic relationships with the 26 reference populations. The results showed that this novel panel exhibited high genetic polymorphism in the studied Korean group and could be effectively applied for forensic individual identification in the Korean group. In addition, the results of multiple population genetic analyses indicated that the ancestral component of the Korean group was dominated by northern East Asia. Moreover, the Korean group was more closely related to the East Asian populations, especially to the Japanese population in Tokyo. This study enriched the genetic data of the Korean ethnic group in China and provided information on the ancestry of the Korean group from the perspective of population genetics.

Free-Space and Fiber-Integrated Measurement-Device-Independent Quantum Key Distribution under High Background Noise.

Measurement-device-independent quantum key distribution (MDI QKD) provides immunity against all attacks targeting measurement devices. It is essential to implement MDI QKD in the future global-scale quantum communication network. Toward this goal, we demonstrate a robust MDI QKD fully covering daytime, overcoming the high background noise that prevents BB84 protocol even when using a perfect single-photon source. Based on this, we establish a hybrid quantum communication network that integrates free-space and fiber channels through Hong-Ou-Mandle (HOM) interference. Additionally, we investigate the feasibility of implementing HOM interference with moving satellites. Our results serve as a significant cornerstone for future integrated space-ground quantum communication networks that incorporate measurement-device-independent security.

A self-developed AIM-InDel panel designed for degraded DNA analysis: Forensic application characterization and genetic landscape investigation in the Han Chinese population.

To assist in forensic DNA investigation, we developed a new panel capable of simultaneously amplifying 56 ancestry-informative InDels, three Y-InDels and the Amelogenin locus in one PCR reaction. The fragment lengths of the InDel amplicons in this panel were restricted to <200 bp to benefit degraded DNA analysis. In this study, we explored the efficiency of this new panel for forensic applications in the Han Chinese population, and further shed light on the genetic structures of Han populations. We showed that the new panel could be served as an efficient tool for ancestry inference of intercontinental populations. Especially, the Han individuals in different regions could be 100% correctly predicted to be of East Asian origin with this new panel. The Han populations in different regions shared similar ancestry components in their genetic structures. Besides, we also revealed that the new panle could be useful for individual identification in different Han Chinese populations. In conclusion, we have provided the necessary evidence that the self-constructed new panel could play an important role in forensic DNA investigation.

Overexpression of the aldehyde dehydrogenase AhALDH3H1 from Arachis hypogaea in soybean increases saline-alkali stress tolerance.

Soybean production is severely hampered by saline-alkaline stress caused by saline-alkalization. Plants have aldehydrogenase (ALDH) family members that convert reactive aldehydes to carboxylic acids to remove active aldehyde molecules. However, little is known about the increased saline-alkali tolerance caused by the ALDH function in soybean. Here, we introduced a previously identified ALDH coding gene AhALDH3H1 from Arachis hypogaea into the soybean genome to investigate its critical role in response to saline-alkali stress. Transgenic soybean with increased aldehyde dehydrogenase activity showed significant tolerance to saline-alkali stress. It reduced malondialdehyde (MDA) content compared to its receptor, suggesting that over-expression of AhALDH3H1 accelerated soybean tolerance to saline-alkali stress by increasing aldehyde dehydrogenase activity, which is responsible for scavenging toxic MDA. To further analyze the inner mechanisms that allow transgenic plants to tolerate saline-alkali stress, we sequenced the transcriptome and metabolome of P3 (wild type, WT) and transgenic lines which were separately treated with water and a saline-alkali solution. When subjected to saline-alkali stress, the integrated analysis of the transcriptome and metabolome suggested that several genes related to cell wall structure crucial for preserving cell wall extensibility and plasticity were largely responsible for restoring homeostasis within the transgenic cells compared to WT. Metabolites, including both necessary ingredients for cell wall genesis and harmful production produced during the saline-alkali stress response, could be transported efficiently with the help of the ABC transporter, reducing the negative effects of saline-alkali stress. These findings suggest that introducing AhALDH3H1 increases transgenic soybean tolerance to saline-alkali stress may through cell wall structure maintenance and metabolites transport.

Two-Stage Multi-Objective Stochastic Model on Patient Transfer and Relief Distribution in Lockdown Area of COVID-19.

The outbreak of an epidemic disease may cause a large number of infections and a slightly higher death rate. In response to epidemic disease, both patient transfer and relief distribution are significant to reduce corresponding damage. This study proposes a two-stage multi-objective stochastic model (TMS-PTRD) considering pre-pandemic preparedness measures and post-pandemic relief operations. The proposed model considers the following four objectives: the total number of untreated infected patients, the total transfer time, the overall cost, and the equity distribution of relief supplies. Before an outbreak, the locations of temporary relief distribution centers (TRDCs) and the inventory levels of established TRDCs should be determined. After an outbreak, the locations of temporary hospitals (THs), the locations of designated hospitals (DHs), the transfer plans for patients, and the relief distribution should be determined. To solve the TMS-PTRD model, we address an improved preference-inspired co-evolutionary algorithm named the PICEA-g-AKNN algorithm, which is embedded with a novel similarity distance and three different tailored evolutionary strategies. A real-world case study of Hunan of China and 18 test instances are randomly generated to evaluate the TMS-PTRD model. The finding shows that the PICEA-g-AKNN algorithm is better than some most widely used multi-objective algorithms.

Identification and functional validation of super-enhancers in Arabidopsis thaliana.

Super-enhancers (SEs) are exceptionally large enhancers and are recognized to play prominent roles in cell identity in mammalian species. We surveyed the genomic regions containing large clusters of accessible chromatin regions (ACRs) marked by deoxyribonuclease (DNase) I hypersensitivity in Arabidopsis thaliana. We identified a set of 749 putative SEs, which have a minimum length of 1.5 kilobases and represent the top 2.5% of the largest ACR clusters. We demonstrate that the genomic regions associating with these SEs were more sensitive to DNase I than other nonpromoter ACRs. The SEs were preferentially associated with topologically associating domains. Furthermore, the SEs and their predicted cognate genes were frequently associated with organ development and tissue identity in A. thaliana. Therefore, the A. thaliana SEs and their cognate genes mirror the functional characteristics of those reported in mammalian species. We developed CRISPR/Cas-mediated deletion lines of a 3,578-bp SE associated with the thalianol biosynthetic gene cluster (BGC). Small deletions (131-157 bp) within the SE resulted in distinct phenotypic changes and transcriptional repression of all five thalianol genes. In addition, T-DNA insertions in the SE region resulted in transcriptional alteration of all five thalianol genes. Thus, this SE appears to play a central role in coordinating the operon-like expression pattern of the thalianol BGC.

Heterologous Expression of Arabidopsis AtARA6 in Soybean Enhances Salt Tolerance.

Salt damage is an important abiotic stress affecting the agronomic traits of soybean. Soybeans rapidly sense and transmit adverse signals when salt-damaged, inducing a set of response mechanisms to resist salt stress. AtARA6 encodes a small GTPase, which plays an important role in Arabidopsis vesicle transport and salt tolerance. In this study, we transformed the Arabidopsis gene AtARA6 into the cultivated soybean Shen Nong 9 (SN9). To investigate the salt tolerance pathways affected by AtARA6 in soybean, we performed transcriptome sequencing using transgenic soybean and wild-type (SN9) under salt treatment and water treatment. Our results suggest that AtARA6 is involved in the regulation of soybean SNARE complexes in the vesicle transport pathway, which may directly strengthen salt tolerance. In addition, we comprehensively analyzed the RNA-seq data of transgenic soybean and SN9 under different treatments and obtained 935 DEGs. GO analysis showed that these DEGs were significantly enriched in transcription factor activity, sequence-specific DNA binding, and the inositol catabolic process. Three salt-responsive negative regulator transcription factors, namely MYC2, WRKY6, and WRKY86, were found to be significantly downregulated after salt treatment in transgenic soybeans. Moreover, four genes encoding inositol oxygenase were significantly enriched in the inositol catabolic process pathway, which could improve the salt tolerance of transgenic soybeans by reducing their reactive oxygen species content. These are unique salt tolerance effects produced by transgenic soybeans. Our results provide basic insights into the function of AtARA6 in soybeans and its role in abiotic stress processes in plants.

Quantum State Transfer over 1200 km Assisted by Prior Distributed Entanglement.

Long-distance quantum state transfer (QST), which can be achieved with the help of quantum teleportation, is a core element of important quantum protocols. A typical situation for QST based on teleportation is one in which two remote communication partners (Alice and Bob) are far from the entanglement source (Charlie). Because of the atmospheric turbulence, it is challenging to implement the Bell-state measurement after photons propagate in atmospheric channels. In previous long-distance free-space experiments, Alice and Charlie always perform local Bell-state measurement before the entanglement distribution process is completed. Here, by developing a highly stable interferometer to project the photon into a hybrid path-polarization dimension and utilizing the satellite-borne entangled photon source, we demonstrate proof-of-principle QST at the distance of over 1200 km assisted by prior quantum entanglement shared between two distant ground stations with the satellite Micius. The average fidelity of transferred six distinct quantum states is 0.82±0.01, exceeding the classical limit of 2/3 on a single copy of a qubit.

Experimental demonstration of free-space two-photon interference.

Quantum interference plays an essential role in understanding the concepts of quantum physics. Moreover, the interference of photons is indispensable for large-scale quantum information processing. With the development of quantum networks, interference of photons transmitted through long-distance fiber channels has been widely implemented. However, quantum interference of photons using free-space channels is still scarce, mainly due to atmospheric turbulence. Here, we report an experimental demonstration of Hong-Ou-Mandel interference with photons transmitted by free-space channels. Two typical photon sources, i.e., correlated photon pairs generated in spontaneous parametric down conversion (SPDC) process and weak coherent states, are employed. A visibility of 0.744 ± 0.013 is observed by interfering with two photons generated in the SPDC process, exceeding the classical limit of 0.5. Our results demonstrate that the quantum property of photons remains even after transmission through unstable free-space channels, indicating the feasibility and potential application of free-space-based quantum interference in quantum information processing.

Trend reversal from source region to remote tropospheric NO2 columns.

Global tropospheric nitrogen dioxide (NO2) changes have different or even opposite impacts on the photochemical formation of ozone in different regions under different weather and emission condition. However, the changes over regions affected by different levels of human activities are not well known. By using the Ozone Monitoring Instrument (OMI) measurements, we analyzed spatial and temporal variability of tropospheric NO2 vertical column densities (VCDs) from the megacity to the background regions during 2005-2019. Consistent with previous research, our results show a rapid decline of tropospheric NO2 column density over regions strongly affected by human activities, especially for source regions. The decline rates of annual mean NO2 VCDs are up to - 2.44% year-1, - 2.37% year-1, and - 1.43% year-1 over megacities of the USA, Europe, and China, respectively. However, the decreasing rate has slowed, and even reversed to an increasing trend, of tropospheric NO2 from megacities to developing and remote regions, especially over ocean and background areas less affected by anthropogenic activity. From 2005 to 2019, the NO2 VCDs over the ocean and background areas increased for all seasons, with the statistically significant (p < 0.05) trends of 1.15%/0.74% year-1 (MAM), 1.20%/1.06% year-1 (JJA), 1.16%/0.82% year-1 (SON), and 0.68%/0.65% year-1 (DJF), respectively, for ocean/background region. Such decreasing/increasing trends of tropospheric NO2 over sources/remote regions may prevent the ozone air pollution to be effectively resolved to achieve air quality goals worldwide.

Validation of a 6-Dye Short Tandem Repeat System: A Dry Kit With Lyophilized Amplification Reagent.

The SureID®S6 system used a lyophilized pellet as the amplification reagent to enable multiplexing of sex-determining marker Amelogenin, 21 autosomal short tandem repeats (STRs), and one Y-STR. To assess the performance, reliability, and limitation of the dry amplification system, the validation studies including PCR condition, reproducibility, sizing and precision, analytical threshold calculation, sensitivity and stochastic threshold calculation, species specificity, stability, mixture, case sample, and population and concordance were conducted according to the Scientific Working Group on DNA Analysis Methods (SWGDAM) Validation Guidelines. Experimental data suggested that the optimal range of total input DNA was from 125 to 500 pg; the appropriate analytical threshold was 80 relative fluorescence units (RFUs) while the stochastic threshold was 260 RFUs; for the stability studies, SureID®S6 system could resist against less than 500 µmol/L of hematin, 100 ng/µl of humic acid, 4 mM of indigotin, 800 mM of tannic acid, and 800 mM of calcium ion. Population and concordance studies using 500 unrelated individuals showed that the combined probability of discrimination (CPD) and cumulative probability of exclusion (CPE) values were 0.999999999999 and 0.999999998416, respectively. The genotypes for the same sample were concordant with the previously validated HUAXIA™ Platinum kit. The validation results demonstrated that the SureID®S6 system could be used for forensic applifications.

The Polymorphism Analyses of Short Tandem Repeats as a Basis for Understanding the Genetic Characteristics of the Guanzhong Han Population.

The short tandem repeat (STR) loci are polymorphic markers in the combined DNA index system (CODIS) and non-CODIS STR loci. Due to the highly polymorphic characteristic of STR loci, they are popular and widely used in forensic DNA typing laboratories. In this study, 22 STR loci (1 CODIS, 21 non-CODIS STR loci) and an Amelogenin locus were genotyped and analyzed in 590 unrelated individuals of the Guanzhong Han population. None of the 22 STR loci deviated from the Hardy-Weinberg equilibrium, and all the loci were in the linkage equilibrium state. We observed 247 alleles, and the corresponding allelic frequencies ranged from 0.0008 to 0.3695 in the Guanzhong Han population. The combined power of discrimination and the cumulative exclusion probability was 0.999 999 999 999 999 999 999 999 999 346 36 and 0.999 999 999 709 74, respectively. The results including Nei's D A genetic distance, multidimensional scaling analysis, and principal component analysis showed that the Guanzhong Han population has closer genetic affinities with Northern Han, Chengdu Han, and Xinjiang Hui groups from China based on allelic frequencies of 15 overlapped STR loci from Guanzhong Han and 13 reference groups. The present results indicated that Microreader™ 23sp ID kit included highly polymorphic loci, and it could be well used for individual identification, paternity testing, and population genetics in the Guanzhong Han population.

Prognostic nomogram for patients with minor stroke and transient ischaemic attack.

BACKGROUND: Ischaemic stroke and transient ischaemic attack (TIA) share a common cause. We aim to develop and validate a concise prognostic nomogram for patients with minor stroke and TIA. METHODS: A total of 994 patients with minor stroke and TIA were included. They were split into a derivation (n=746) and validation (n=248) cohort. The modified Rankin Scale (mRS) scores 3 months after onset were used to assess the prognosis as unfavourable outcome (mRS≥2) or favourable outcome (mRS<2). RESULT: The final model included seven independent predictors: gender, age, baseline National Institute of Health Stroke Scale (NIHSS), hypertension, diabetes mellitus, white blood cell and serum uric acid. The Harrell's concordance index (C-index) of the nomogram for predicting the outcome was 0.775 (95% CI 0.735 to 0.814), which was confirmed by the validation cohort (C-index=0.787 (95% CI 0.722 to 0.853)). The calibration curve showed that the nomogram-based predictions were consistent with actual observation in both derivation cohort and validation cohort. CONCLUSION: The proposed nomogram showed favourable predictive accuracy for minor stroke and TIA. This has the potential to contribute to clinical decision-making.

Systematic Evaluation of a Novel 6-dye Direct and Multiplex PCR-CE-Based InDel Typing System for Forensic Purposes.

Insertion/deletion (InDel) polymorphisms, combined desirable characteristics of both short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs), are considerable potential in the fields of forensic practices and population genetics. However, most commercial InDel kits designed based on non-Asians limited extensive forensic applications in East Asian (EAS) populations. Recently, a novel 6-dye direct and multiplex PCR-CE-based typing system was designed on the basis of genome-wide EAS population data, which could amplify 60 molecular genetic markers, consisting of 57 autosomal InDels (A-InDels), 2 Y-chromosomal InDels (Y-InDels), and Amelogenin in a single PCR reaction and detect by capillary electrophoresis, simultaneously. In the present study, the DNA profiles of 279 unrelated individuals from the Hainan Li group were generated by the novel typing system. In addition, we collected two A-InDel sets to evaluate the forensic performances of the novel system in the 1,000 Genomes Project (1KG) populations and Hainan Li group. For the Universal A-InDel set (UAIS, containing 44 A-InDels) the cumulative power of discrimination (CPD) ranged from 1-1.03 × 10-14 to 1-1.27 × 10-18, and the cumulative power of exclusion (CPE) varied from 0.993634 to 0.999908 in the 1KG populations. For the East Asia-based A-InDel set (EAIS, containing 57 A-InDels) the CPD spanned from 1-1.32 × 10-23 to 1-9.42 × 10-24, and the CPE ranged from 0.999965 to 0.999997. In the Hainan Li group, the average heterozygote (He) was 0.4666 (0.2366-0.5448), and the polymorphism information content (PIC) spanned from 0.2116 to 0.3750 (mean PIC: 0.3563 ± 0.0291). In total, the CPD and CPE of 57 A-InDels were 1-1.32 × 10-23 and 0.999965, respectively. Consequently, the novel 6-dye direct and multiplex PCR-CE-based typing system could be considered as the reliable and robust tool for human identification and intercontinental population differentiation, and supplied additional information for kinship analysis in the 1KG populations and Hainan Li group.

Single-mode fiber coupling with a M-SPGD algorithm for long-range quantum communications.

Satellite-based quantum communication is a promising approach for realizing global-scale quantum networks. For free-space quantum channel, single-mode fiber coupling is particularly important for improving the signal-to-noise ratio of daylight quantum key distribution (QKD) and compatibility with standard fiber-based QKD. However, achieving a highly efficient and stable single-mode coupling efficiency under strong atmospheric turbulence remains experimentally challenging. Here, we develop a single-mode receiver with an adaptive optics (AO) system based on a modal version of the stochastic parallel gradient descent (M-SPGD) algorithm and test its performance over an 8 km urban terrestrial free-space channel. Under strong atmospheric turbulence, the M-SPGD AO system obtains an improvement of about 3.7 dB in the single-mode fiber coupling efficiency and a significant suppression of fluctuation, which can find its applications in free-space long-range quantum communications.

Entanglement-based secure quantum cryptography over 1,120 kilometres.

Quantum key distribution (QKD)1-3 is a theoretically secure way of sharing secret keys between remote users. It has been demonstrated in a laboratory over a coiled optical fibre up to 404 kilometres long4-7. In the field, point-to-point QKD has been achieved from a satellite to a ground station up to 1,200 kilometres away8-10. However, real-world QKD-based cryptography targets physically separated users on the Earth, for which the maximum distance has been about 100 kilometres11,12. The use of trusted relays can extend these distances from across a typical metropolitan area13-16 to intercity17 and even intercontinental distances18. However, relays pose security risks, which can be avoided by using entanglement-based QKD, which has inherent source-independent security19,20. Long-distance entanglement distribution can be realized using quantum repeaters21, but the related technology is still immature for practical implementations22. The obvious alternative for extending the range of quantum communication without compromising its security is satellite-based QKD, but so far satellite-based entanglement distribution has not been efficient23 enough to support QKD. Here we demonstrate entanglement-based QKD between two ground stations separated by 1,120 kilometres at a finite secret-key rate of 0.12 bits per second, without the need for trusted relays. Entangled photon pairs were distributed via two bidirectional downlinks from the Micius satellite to two ground observatories in Delingha and Nanshan in China. The development of a high-efficiency telescope and follow-up optics crucially improved the link efficiency. The generated keys are secure for realistic devices, because our ground receivers were carefully designed to guarantee fair sampling and immunity to all known side channels24,25. Our method not only increases the secure distance on the ground tenfold but also increases the practical security of QKD to an unprecedented level.