Quantum Interference and Coherent Population Trapping in a Double Quantum Dot.

Quantum interference is a natural consequence of wave-particle duality in quantum mechanics, and is widely observed at the atomic scale. One interesting manifestation of quantum interference is coherent population trapping (CPT), first proposed in three-level driven atomic systems and observed in quantum optical experiments. Here, we demonstrate CPT in a gate-defined semiconductor double quantum dot (DQD), with some unique twists as compared to the atomic systems. Specifically, we observe CPT in both driven and nondriven situations. We further show that CPT in a driven DQD could be used to generate adiabatic state transfer. Moreover, our experiment reveals a nontrivial modulation to the CPT caused by the longitudinal driving field, yielding an odd-even effect and a tunable CPT. Our results broaden the field of CPT, and open up the possibility of quantum simulation and quantum computation based on adiabatic passage in quantum dot systems.

High-Precision Measurements of 44Ca/40Ca Using Multiple-Collector Inductively Coupled Plasma Mass Spectrometry without Collision-Cell Technology.

Herein, we present a new method for determining the Ca isotopic composition of geological samples. To eliminate matrix elements from Ca, a column chromatography method was developed using a N,N,N'N' tetraoctyl-1,5-diglycolamide (TODGA) resin. The Ca isotopic compositions were measured by a multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) without collision cell equipment, especially that direct measurement to 44Ca/40Ca can be achieved. To mitigate the interference from 40Ar during 40Ca measurement, the cold plasma technique was used to suppress the Ar+ generation, resulting in a background Ar+ intensity of <300 mV, in contrast to the conventional hot plasma conditions, which typically yield thousands of volts for Ar+ intensities. Given the potential for a concentration mismatch between the sample and bracketed standard solutions to cause an intensive shift in measured Ca isotopic compositions, a correction for the [Ca] match is needed. To avoid matrix effects arising from residue matrix elements, it is crucial to limit the concentrations below 1% of Ca for most matrix elements (including Al, Mg, K, Na, and Sr) and below 1‰ for Fe. Notably, the tolerance of residue Sr is effectively improved compared to measurements with CC-MC-ICP-MS and traditional Hot-plasma-SSB-MC-ICP-MS methods with the conventional hot plasma technique, thereby lowering the complexity of column chemistry. The measured δ44/40Ca, δ44/42Ca, and ε40Ca values for eight reference materials agree well with previously reported values within analytical uncertainties. This method demonstrates long-term precision is better than 0.10‰ (two standard deviations) for both δ values (i.e., δ44/40Ca and δ44/42Ca). We anticipate that the proposed method will benefit the growth of the Ca isotope data set and foster an increase in the application of Ca isotope in Earth science studies.

Magnetic detection under high pressures using designed silicon vacancy centres in silicon carbide.

Pressure-induced magnetic phase transitions are attracting interest as a means to detect superconducting behaviour at high pressures in diamond anvil cells, but determining the local magnetic properties of samples is a challenge due to the small volumes of sample chambers. Optically detected magnetic resonance of nitrogen vacancy centres in diamond has recently been used for the in situ detection of pressure-induced phase transitions. However, owing to their four orientation axes and temperature-dependent zero-field splitting, interpreting these optically detected magnetic resonance spectra remains challenging. Here we study the optical and spin properties of implanted silicon vacancy defects in 4H-silicon carbide that exhibit single-axis and temperature-independent zero-field splitting. Using this technique, we observe the magnetic phase transition of Nd2Fe14B at about 7 GPa and map the critical temperature-pressure phase diagram of the superconductor YBa2Cu3O6.6. These results highlight the potential of silicon vacancy-based quantum sensors for in situ magnetic detection at high pressures.

The long rod-shaped Sr2 MgSi2 O7 :Eu2+ ,Dy3+ with ultrahigh afterglow performance.

The afterglow properties of long afterglow luminescent materials are greatly affected by their defects, which are distributed on the grain surface. Increasing the exposed surface area is an important method to improve the afterglow performance. In this research, long rod-shaped long afterglow materials Sr2 MgSi2 O7 :Eu2+ ,Dy3+ were prepared using the hydrothermal-coprecipitation method. When the reaction time reached 96 h, the length of the afterglow materials could grow to 2 mm, and the sintering temperature was just 1150°C. The emission spectra of all obtained samples upon excitation at 397 nm had a maximum of 465 nm, which belonged to the representative transition of Eu2+ . The initial brightness was 1.35 cd/m2 . The afterglow time could reach 19 h, giving a good afterglow performance. The research on this kind of material has essential significance in the exploration of luminescence mechanisms and their applications.

Ultrafast and Electrically Tunable Rabi Frequency in a Germanium Hut Wire Hole Spin Qubit.

Hole spin qubits based on germanium (Ge) have strong tunable spin-orbit interaction (SOI) and ultrafast qubit operation speed. Here we report that the Rabi frequency (fRabi) of a hole spin qubit in a Ge hut wire (HW) double quantum dot (DQD) is electrically tuned through the detuning energy (ϵ) and middle gate voltage (VM). fRabi gradually decreases with increasing ϵ; on the contrary, fRabi is positively correlated with VM. We attribute our results to the change of electric field on SOI and the contribution of the excited state in quantum dots to fRabi. We further demonstrate an ultrafast fRabi exceeding 1.2 GHz, which indicates the strong SOI in our device. The discovery of an ultrafast and electrically tunable fRabi in a hole spin qubit has potential applications in semiconductor quantum computing.

Collective Microwave Response for Multiple Gate-Defined Double Quantum Dots.

We fabricate and characterize a hybrid quantum device that consists of five gate-defined double quantum dots (DQDs) and a high-impedance NbTiN transmission resonator. The controllable interactions between DQDs and the resonator are spectroscopically explored by measuring the microwave transmission through the resonator in the detuning parameter space. Utilizing the high tunability of the system parameters and the high cooperativity (Ctotal > 17.6) interaction between the qubit ensemble and the resonator, we tune the charge-photon coupling and observe the collective microwave response changing from linear to nonlinear. Our results present the maximum number of DQDs coupled to a resonator and manifest a potential platform for scaling up qubits and studying collective quantum effects in semiconductor-superconductor hybrid cavity quantum electrodynamics systems.

Probing Two Driven Double Quantum Dots Strongly Coupled to a Cavity.

We experimentally and theoretically study a driven hybrid circuit quantum electrodynamics (cQED) system beyond the dispersive coupling regime. Treating the cavity as part of the driven system, we develop a theory applicable to such strongly coupled and to multiqubit systems. The fringes measured for a single driven double quantum dot (DQD)-cavity setting and the enlarged splittings of the hybrid Floquet states in the presence of a second DQD are well reproduced with our model. This opens a path to study Floquet states of multiqubit systems with arbitrarily strong coupling and reveals a new perspective for understanding strongly driven hybrid systems.

Combination of mathematics and label-free proteomics for discovering keratin-derived specific peptide biomarkers to distinguish animal horn-derived traditional Chinese medicines.

Saiga antelope horn and Rhinoceros horn have been used in traditional Chinese medicine for thousands of years. However, due to the protection of wildlife, the application of these rare animal horns has been restricted or prohibited. Therefore, water buffalo horn, goat horn, and yak horn have been applied as alternatives to Rhinoceros horn or Saiga antelope horn in a clinic. It is extremely difficult to distinguish normal animal horns in powdered or decocted form, especially identifying related species such as water buffalo horn, yak horn, and cattle horn. In this work, mathematics set and label-free proteomics analysis were combined for discovering keratin-derived specific peptide biomarkers. By using mathematics set analysis after nano liquid chromatography-tandem mass spectrometry-based proteomics, the selected species-specific peptides could be used to identify the authenticity of the Saiga antelope horn and goat horn. Furthermore, peptide biomarkers were selected to distinguish related species-derived horns, water buffalo horn, yak horn, and cattle horn. In total, eight peptide biomarkers were selected and applied for simultaneously distinguishing different horn samples. The present strategy provides a method for peptide biomarkers discovery and also has positive significance for ensuring the quality and efficacy of animal horn-derived traditional Chinese medicines and their products.

Coherent phonon dynamics in spatially separated graphene mechanical resonators.

Vibrational modes in mechanical resonators provide a promising candidate to interface and manipulate classical and quantum information. The observation of coherent dynamics between distant mechanical resonators can be a key step toward scalable phonon-based applications. Here we report tunable coherent phonon dynamics with an architecture comprising three graphene mechanical resonators coupled in series, where all resonators can be manipulated by electrical signals on control gates. We demonstrate coherent Rabi oscillations between spatially separated resonators indirectly coupled via an intermediate resonator serving as a phonon cavity. The Rabi frequency fits well with the microwave burst power on the control gate. We also observe Ramsey interference, where the oscillation frequency corresponds to the indirect coupling strength between these resonators. Such coherent processes indicate that information encoded in vibrational modes can be transferred and stored between spatially separated resonators, which can open the venue of on-demand phonon-based information processing.

Coherent Control and Magnetic Detection of Divacancy Spins in Silicon Carbide at High Pressures.

Spin defects in silicon carbide appear to be a promising tool for various quantum technologies, especially for quantum sensing. However, this technique has been used only at ambient pressure until now. Here, by combining this technique with diamond anvil cell, we systematically study the optical and spin properties of divacancy defects created at the surface of SiC at pressures up to 40 GPa. The zero-field-splitting of the divacancy spins increases linearly with pressure with a slope of 25.1 MHz/GPa, which is almost two-times larger than that of nitrogen-vacancy centers in diamond. The corresponding pressure sensing sensitivity is about 0.28 MPa/Hz-1/2. The coherent control of divacancy demonstrates that coherence time decreases as pressure increases. Based on these, the pressure-induced magnetic phase transition of Nd2Fe14B sample at high pressures was detected. These experiments pave the way to use divacancy in quantum technologies such as pressure sensing and magnetic detection at high pressures.

YUCCA2 (YUC2)-Mediated 3-Indoleacetic Acid (IAA) Biosynthesis Regulates Chloroplast RNA Editing by Relieving the Auxin Response Factor 1 (ARF1)-Dependent Inhibition of Editing Factors in Arabidopsis thaliana.

Although recent research progress on the abundant C-to-U RNA editing events in plant chloroplasts and mitochondria has uncovered many recognition factors and their molecular mechanisms, the intrinsic regulation of RNA editing within plants remains largely unknown. This study aimed to establish a regulatory relationship in Arabidopsis between the plant hormone auxin and chloroplast RNA editing. We first analyzed auxin response elements (AuxREs) present within promoters of chloroplast editing factors reported to date. We found that each has more than one AuxRE, suggesting a potential regulatory role of auxin in their expression. Further investigation unveiled that the depletion of auxin synthesis gene YUC2 reduces the expression of several editing factors. However, in yuc2 mutants, only the expression of CRR4, DYW1, ISE2, and ECD1 editing factors and the editing efficiency of their corresponding editing sites, ndhD-2 and rps14-149, were simultaneously suppressed. In addition, exogenous IAA and the overexpression of YUC2 enhanced the expression of these editing factors and the editing efficiency at the ndhD-2 and rps14-149 sites. These results suggested a direct effect of auxin upon the editing of the ndhD-2 and rps14-149 sites through the modulation of the expression of the editing factors. We further demonstrated that ARF1, a downstream transcription factor in the auxin-signaling pathway, could directly bind to and inactivate the promoters of CRR4, DYW1, and ISE2 in a dual-luciferase reporter system, thereby inhibiting their expression. Moreover, the overexpression of ARF1 in Arabidopsis significantly reduced the expression of the three editing factors and the editing efficiency at the ndhD-2 and rps14-149 sites. These data suggest that YUC2-mediated auxin biosynthesis governs the RNA-editing process through the ARF1-dependent signal transduction pathway.

Prevalence of Adverse Childhood Experiences and Their Associations with Non-Suicidal Self-Injury Among Chinese Adolescents with Depression.

The presence of adverse childhood experiences (ACEs) in adolescents diagnosed with depression has been associated with an extensive range of mental health issues, including non-suicidal self-injury (NSSI). However, there has been a dearth of research into the prevalence of ACEs and their associations with NSSI among depressed adolescent populations in China. This study aimed to investigate the prevalence of different types of ACEs and their associations with NSSI in depressed Chinese adolescents. Utilizing Chi-squared tests, latent class analysis (LCA), and multinomial logistic regression, the prevalence of different types of ACEs and their associations with NSSI were determined in a sample of 562 adolescents with depression. Among depressed adolescents. 92.9% of depressed adolescents reported ACEs, and the prevalence of emotional neglect, physical abuse, caregiver treated violently, and bullying was relatively high. ACEs, including sexual abuse (OR = 5.645), physical abuse (OR = 3.603), emotional neglect (OR = 3.096), emotional abuse (OR = 2.701), caregiver divorce/family separation (OR = 2.5), caregiver treated violently (OR = 2.221), and caregiver substance abuser (OR = 2.117), were associated with increased odds of exposure among depressed adolescents with NSSI. The high ACEs class (19%), the moderate ACEs class (40%), and the low ACEs class (41%) were identified as latent classes. NSSI was more prevalent in the high/moderate ACEs class compared to the low ACEs class, particularly in the high ACEs class. The situation of the prevalence of ACEs among adolescents with depression was unsatisfactory, and certain types of ACEs were associated with NSSI. Eliminating potential risk factors for NSSI requires the early prevention and targeted intervention of ACEs. Moreover, additional large-scale longitudinal studies are necessary to assess the different development trajectories associated with ACEs, such as the relationships between the different development periods of ACEs and NSSI, and to ensure the adoption of evidence-based prevention and intervention strategies.

Anisotropic g-Factor and Spin-Orbit Field in a Germanium Hut Wire Double Quantum Dot.

Holes in nanowires have drawn significant attention in recent years because of the strong spin-orbit interaction, which plays an important role in constructing Majorana zero modes and manipulating spin-orbit qubits. Here, from the strongly anisotropic leakage current in the spin blockade regime for a double dot, we extract the full g-tensor and find that the spin-orbit field is in plane with an azimuthal angle of 59° to the axis of the nanowire. The direction of the spin-orbit field indicates a strong spin-orbit interaction along the nanowire, which may have originated from the interface inversion asymmetry in Ge hut wires. We also demonstrate two different spin relaxation mechanisms for the holes in the Ge hut wire double dot: spin-flip co-tunneling to the leads, and spin-orbit interaction within the double dot. These results help establish feasibility of a Ge-based quantum processor.

Posttraumatic growth in Chinese nurses and general public during the COVID-19 outbreak.

COVID-19 as a pandemic disease, till 18 May 2020, has infected more than 84,494 people in China and 4721,051 abroad. While countries around the world concentrate on controlling the pandemic to minimize damage to this country, the positive psychology brought to nurses and general public (GP) by COVID-19 should not be ignored. This study aims to assess post-traumatic growth (PTG) of Chinese nurses and GP during the COVID-19 pandemic. The study employed PTG in Chinese nurses and GP with Posttraumatic growth inventory questionnaire (PTGI) via a mobile app-based questionnaire, anxiety and ways to copy with stress in nurses were also employed. A total of 455 nurses and 424 GP were included in the statistical analysis. Results indicated that score of total PTGI and three dimensions, new possibilities, personal strength and spiritual change, were different between nurses and GP. Furthermore, score of total PTGI and all domains were significantly different between 178 front-line nurses (FLNs) and 277 non-front-line nurses (nFLNs). Importantly, sex, marriage status, professional titles, fertility, anxiety and ways to copy with stress were associated with PTG in nurses. Moreover, marriage status and ways to copy with stress were the predictors of PTG in nurses. Interestingly, this study found that WeChat network psychological counseling and phone app of application self-relaxation were good and effective coping strategies for nurses to relieve stress. Thus, the development of valid intervention programs for nurses to diminish job burnout and increase care quality was also important.

[International Research Status and Trend of Community Palliative Care:A Study Based on Cite Space].

Objective To systematically analyze the international progress of community palliative care and to provide reference for promoting the development of community palliative care in China.Methods We searched the Web of Science core collection of the English-language papers associated with community palliative care published from January 1,2014 to November 1,2021 and then used CiteSpace 5.8.R1 to establish the cooperation and co-occurrence networks.Results A total of 1509 papers were included in this study.The annual number of published papers and the citations associated with community palliative care showed an increasing trend.The country,institution,and author publishing the most papers in this field were the United States,the King's College London,and Irene J Higginson at the King's College London,respectively.The research hotspot was identified as hospice of end-of-life patients like cancer patients,which aimed at improving the quality of life.The care will be expanded to dementia patients and old people.Research subjects involve family caregiver and palliative care worker.The predicted focuses of future studies include intervention methods and efficacy,patients' preference,and advance care planning.Conclusions Community palliative care has been rapidly developing in recent years and expanding from patients to the whole population for a full-life care.The Chinese researchers need to strengthen international exchange and cooperation and to learn the diverse development approaches for the whole population,thereby promoting the practice and development of community palliative care in China.

[Obstacles in the Practice of Palliative Care Consultation Services in Grade A Tertiary Hospitals].

Objective To explore the obstacles in palliative care consultation services and put forward the suggestions for improving the services in grade A tertiary hospitals. Methods A semi-structured interview was conducted with 17 medical workers who had requested palliative care consultation services in Peking Union Medical College Hospital. Results The palliative care consultation services were hindered by five obstacle factors including insufficient knowledge of patients and their families about palliative care,unsound understanding of medical workers about palliative care,poor implementation of consultation opinions,limited labor of palliative care team,and poor economic benefits from palliative care.In view of such obstacles,the following suggestions were put forward,which included increasing the acceptance of palliative care by patients and their families,enriching the knowledge of medical staff on palliative care,establishing a new cooperation model between consultation team and medical staff,strengthening the institutional guarantee for the development of palliative care,and establishing and perfecting the laws and policies related to palliative care. Conclusion Although there are many difficulties in the in-hospital palliative care consultation services in grade A tertiary hospitals,the demand and expectation of medical staff for palliative care are still increasing.

Application of a "Continuous-Acquisition-Method" to potassium isotope measurements by multi-collector inductively coupled plasma mass spectrometry.

RATIONALE: The very small mass difference between 41 K and 40 ArH+ makes the flat, hydride interference-free peak shoulders very narrow (0.002-0.003 m/z unit), bringing a number of analytical challenges when measuring K isotopic compositions by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). In traditional Sequence Run mode, the parameters are loaded every line of the sequence which can introduce tiny drifts of tune parameters and mass peaks. This may occasionally lead to the failure of K isotope measurements when mass drifts exceed 0.002 m/z unit. It is thus essential to keep the tune parameters, especially the magnet current, very stable to achieve high-precision K isotopic compositions. METHOD: We developed a "Continuous-Acquisition-Method" (CAM) MC-ICP-MS Run mode to improve the stability when determining K isotopes. Two sets of experiments were designed: (a) Stability test: measuring a single pure K solution (viz. NIST-999c) for ~3 h and comparing the stability of the two run modes; and (b) GSB-K test: measuring our inhouse pure K standard solution (GSB-K) in both run modes and comparing the accuracy and precision. RESULTS: The traditional Sequence Run mode only kept the MC-ICP-MS system stable for the first ~1.5 h during the ~3-h test, with an offset of the mass peaks of ~0.003 m/z unit. The CAM Run mode yielded higher stability during the whole test (~3 h), with a peak shift <0.0004 m/z unit. Measurement of the GSB-K standard solution in Sequence Run and CAM Run modes gives identical δ41 K values when the magnet was kept stable, with the CAM Run mode offering a better precision and keeping the instrument stable for longer time. CONCLUSIONS: The MC-ICP-MS CAM Run mode shows higher stability and better precision. It is, therefore, good for high-precision K isotope measurements.

Effect of Oxygen Vacancies on the Persistent Luminescence of Y3Al2Ga3O12:Ce3+,Yb3+ Phosphors.

The effect of oxygen vacancies (VO) and the atmosphere influence on persistent luminescence (PersL) in Y3Al2Ga3O12 (YAGG):Ce3+,Yb3+ are investigated by heating it in CO2, air, and 10% H2/90% Ar atmospheres. The VO-rich YAGG phosphors with outstanding PersL are successfully obtained by the common contribution of the reducing atmosphere and the incorporated Yb3+ ions, and the concentration of oxygen vacancies in the phosphors is characterized by X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. Compared to the best sample prepared in neutral CO2, the reduced sample shows an increase of 30% in initial intensity and 100% in duration time, while the oxidized sample decreases drastically and shows a faint and undetectable PersL. The enhancement is mainly caused by the abundant formation of VO, which is achieved by the pairing of VO with Yb2+ ions. The newly created VO by the reducing calcination is inferred to be adjacent to the Yb site and forms a compensation-type defect cluster due to the charge compensation effect. These findings reveal that understanding the effect and formation of VO is of great significance to design a high-performance phosphor.

Tunable parametric amplification of a graphene nanomechanical resonator in the nonlinear regime.

Parametric amplification is widely used in nanoelectro-mechanical systems to enhance the transduced mechanical signals. Although parametric amplification has been studied in different mechanical resonator systems, the nonlinear dynamics involved receives less attention. Taking advantage of the excellent electrical and mechanical properties of graphene, we demonstrate electrical tunable parametric amplification using a doubly clamped graphene nanomechanical resonator. By applying external microwave pumping with twice the resonant frequency, we investigate parametric amplification in the nonlinear regime. We experimentally show that the extracted coefficient of the nonlinear Duffing force α and the nonlinear damping coefficient η vary as a function of external pumping power, indicating the influence of higher-order nonlinearity beyond the Duffing (∼x 3) and van der Pol (∼[Formula: see text]) types in our device. Even when the higher-order nonlinearity is involved, parametric amplification still can be achieved in the nonlinear regime. The parametric gain increases and shows a tendency of saturation with increasing external pumping power. Further, the parametric gain can be electrically tuned by the gate voltage with a maximum gain of 10.2 dB achieved at the gate voltage of 19 V. Our results will benefit studies on nonlinear dynamics, especially nonlinear damping in graphene nanomechanical resonators that has been debated in the community over past decade.

[Effects of Palliative Care Consultation on Medicals in Peking Union Medical College Hospital].

Objective To explore the effects of palliative care consultation on medical professionals who have requested it in Peking Union Medical College Hospital. Methods Semi-structured interviews were conducted with 17 medical professionals who had requested palliative care consultation.Results Palliative care consultation had the following positive effects:building a bridge for doctor-patient communication,providing psychological support to reduce the sense of occupational exhaustion for medical professionals,providing technical support for medical professionals to help patients relieve symptoms,helping medical professionals in the multidisciplinary learning of palliative care,adding humanistic care and neglected ethical concerns.Conclusion Palliative care consultation improves the quality of care for dying patients,and the capacity of consultation needs to be enhanced urgently.