教育、科技、人才一体布局与科学基金发展战略

教育、科技、人才一体布局的统筹部署已经成为全面建设社会主义现代化国家的基础性、战略性支撑,深刻理解与把握教育、科技、人才一体布局重大意义对开展基础研究资助至关重要。在厘清一体布局对基础研究资助新要求的前提下,明确基础研究资助在科学研究、科学教育与人才培养有机结合中的定位和作用,完善国家自然科学基金资助管理体系,探索落实一体布局的着力点,从而提出新时代科学基金发展的战略思路,为教育强国、科技强国、人才强国建设提供源头支撑。

Micro-Gas Flow Induced Stochastic Resonance of a Nonlinear Nanomechanical Resonator

Fluidics is one of the most historic subjects that are well-established over centuries on the macroscopic scale.In recent years,fluid detection using a number of micro/nano scale devices has been achieved.However,the interaction of microfluid and solid devices on micro/nano-meter scale still lacks in-depth research.We demonstrate a practical nanomechanical detector for microfluidics via a string resonator with high Q-factor,suspended over a hole.This device is placed under a jet nozzle with several microns of diameter,and the interaction between the micro-gas flow and the resonator is observed by monitoring the variation of the fundamental frequency and the quality factor.Moreover,we manage to measure the fluctuations of the micro-gas flow on the nanomechanical resonator by means of stochastic resonance.This work manifests a potential platform for detecting dynamical fluid behaviors at microscopic scale for novel fluid physics.

Design optimization of high breakdown voltage vertical GaN junction barrier Schottky diode with high-K/low-K compound dielectric structure

A vertical junction barrier Schottky diode with a high-K/low-K compound dielectric structure is proposed and optimized to achieve a high breakdown voltage(BV).There is a discontinuity of the electric field at the interface of high-K and low-K layers due to the different dielectric constants of high-K and low-K dielectric layers.A new electric field peak is introduced in the n-type drift region of junction barrier Schottky diode(JBS),so the distribution of electric field in JBS becomes more uniform.At the same time,the effect of electric-power line concentration at the p-n junction interface is suppressed due to the effects of the high-K dielectric layer and an enhancement of breakdown voltage can be achieved.Numerical simulations demonstrate that GaN JBS with a specific on-resistance(R_(on,sp)) of 2.07 mΩ·cm^(2) and a BV of 4171 V which is 167% higher than the breakdown voltage of the common structure,resulting in a high figure-of-merit(FOM) of 8.6 GW/cm^(2),and a low turn-on voltage of 0.6 V.

Hemin blocks TIGIT/PVR interaction and induces ferroptosis to elicit synergistic effects of cancer immunotherapy

The immune checkpoint TIGIT/PVR blockade exhibits significant antitumor effects through activation of NK and CD8^(+)T cell-mediated cytotoxicity.Immune checkpoint blockade(ICB)could induce tumor ferroptosis through IFN-γreleased by immune cells,indicating the synergetic effects of ICB with ferroptosis in inhibiting tumor growth.However,the development of TIGIT/PVR inhibitors with ferroptosis-inducing effects has not been explored yet.In this study,the small molecule Hemin that could bind withTIGIT to block TIGIT/PVR interaction was screened by virtual molecular docking and cell-based blocking assay.Hemin could effectively restore the IL-2 secretion from Jurkat-hTIGIT cells.Hemin reinvigorated the function of CD8^(+)T cells to secrete IFN-γand the elevated IFN-γcould synergize with Hemin to induce ferroptosis in tumor cells.Hemin inhibited tumor growth by boosting CD8^(+)T cell immune response and inducing ferroptosis in CT26 tumor model.More importantly,Hemin in combination with PD-1/PD-L1 blockade exhibited more effective antitumor efficacy in anti-PD-1 resistant B16 tumor model.In summary,our finding indicated that Hemin blocked TIGIT/PVR interaction and induced tumor cell ferroptosis,which provided a new therapeutic strategy to combine immunotherapy and ferroptosis for cancer treatment.

A high performance fast-Fourier-transform spectrum analyzer for measuring spin noise spectrums

A high performance fast-Fourier-transform (FFT) spectrum analyzer, which is developed for measure spin noise spectrums, is presented in this paper. The analyzer is implemented with a field-programmable-gate-arrays (FPGA) chip for data and command management. An analog-to-digital-convertor chip is integrated for analog signal acquisition. In order to meet the various requirements of measuring different types of spin noise spectrums, multiple operating modes are designed and realized using the reprogrammable FPGA logic resources. The FFT function is fully managed by the programmable resource inside the FPGA chip. A 1 GSa/s sampling rate and a 100 percent data coverage ratio with non-dead-time are obtained. 30534 FFT spectrums can be acquired per second, and the spectrums can be on-board accumulated and averaged. Digital filters, multi-stage reconfigurable data reconstruction modules, and frequency down conversion modules are also implemented in the FPGA to provide flexible real-time data processing capacity, thus the noise floor and signals aliasing can be suppressed effectively. An efficiency comparison between the FPGA-based FFT spectrum analyzer and the software-based FFT is demonstrated, and the high performance FFT spectrum analyzer has a significant advantage in obtaining high resolution spin noise spectrums with enhanced efficiency.

Experimental Protection of the Spin Coherence of a Molecular Qubit Exceeding a Millisecond

Molecular qubits are promising as they can benefit from tailoring and versatile design of chemistry.It is essential to reduce the decoherence of molecular qubits caused by their interactions with the environment.Herein the dynamical decoupling(DD)technique is utilized to combat such decoherence.The coherence time for a transitionmetal complex(PPh_(4))_(2)[Cu(mnt)_(2)]is prolonged from 6.8μs to 1.4 ms.The ratio of the coherence time and the length ofπ/2 pulse,defined as the single qubit figure of merit(QM),reaches 1.4×10^(5),which is 40 times greater than what previously reported for this molecule.Our results show that molecular qubits,with milliseconds coherence time,are promising candidates for quantum information processing.

Physics of quantum coherence in spin systems

Quantum computation provides a great speedup over its classical counterpart in solving some hard problems. The advantages of quantum computation come from the coherent superposition principle of quantum mechanics. Spin system is one of the most significant candidates to realize quantum computation. In this review, we focus on the recent experimental progress related to quantum coherence and some fundamental concepts such as the uncertainty principle in the spin systems.We shall first briefly introduce the quantum description of qubit, coherence, and decoherence. Based on this picture,preserving quantum coherence and detection of weak magnetic fields are presented. We also discuss the realization of precise quantum coherent control, adiabatic quantum factorization algorithm, and two aspects of uncertainty relations.

Experimental implementation of a continuous-time quantum random walk on a solid-state quantum information processor

There are some problems that quantum computers seem to be exponentially faster than classical computers, like factoring large numbers, machine learning, and simulation of quantum systems. Constructing an appropriate quantum algorithm becomes more important for solving these specific problems. In principle, any quantum algorithm can recast by a quantum random walk algorithm. Although quantum random walk with a few qubits has been implemented in a variety of systems, the experimental demonstration of solid-state quantum random walk remains elusive. Here we report the experimental implementation of the quantum continuous-time random walk algorithm by a two-qubit quantum processor in a nitrogen–vacancy center in diamond. We found that quantum random walk on a circle does not converge to any stationary distribution and exhibit a reversible property. Our results represent a further investigation of quantum walking dynamics in solid spin platforms, may also lead to other practical applications by the use of quantum continuous-time random walk for quantum algorithm design and quantum coherence transport.

A design of resonant cavity with an improved coupling-adjusting mechanism for the W-band EPR spectrometer

We report a new design of resonant cavity for a W-band electron paramagnetic resonance(EPR)spectrometer.An improved coupling-adjusting mechanism,which is robust,compact,and suits with both solenoid-type and split-pair magnets,is utilized on the cavity,and thus enables both continuous-wave(CW)and pulsed EPR experiments.It is achieved by a tiny metal cylinder in the iris.The coupling coefficient can be varied from 0.2 to 17.9.Furthermore,two pistons at each end of the cavity allow for adjustment of the resonant frequency.A horizontal TE_(011) geometry also makes the cavity compatible with the two frequently used types of magnets.The coupling-varying ability has been demonstrated by reflection coefficient(S_(11))measurement.CW and pulsed EPR experiments have been conducted.The performance data indicates a prospect of wide applications of the cavity in fields of physics,chemistry and biology.

Magnetic Phase Transition in Two-Dimensional CrBr_(3) Probed by a Quantum Sensor

Recently,magnetism in two-dimensional(2 D)van der Waals(vd W)materials has attracted wide interests.It is anticipated that these materials will stimulate discovery of new physical phenomena and novel applications.The capability to quantitatively measure the magnetism of 2 D magnetic vd W materials is essential to understand these materials.Here we report on quantitative measurements of ferromagnetic-to-paramagnetic phase transition of an atomically thin(down to 11 nm)vd W magnet,namely Cr Br_(3),with a Curie point of 37.5 K.This experiment demonstrates that surface magnetism can be quantitatively investigated,which is useful for a wide variety of potential applications.

Coherent Transfer of Excitation in a Nanomechanical Artificial Lattice

We realize a coherent transfer of mechanical excitation in a finely controlled artificial nanomechanical lattice.We also realize strong dynamic coupling between adjacent high-Q mechanical resonators,via modulated dielectric force at the frequency difference between them.An excitation transfer across a lattice consisting of 7 nanobeams is observed by applying a design sequence of switching for couplings,with the final effective population reaching 0.94.This work not only demonstrates the ability to fully control an artificial lattice but also provides an efficient platform for studying complicated dynamics in one-dimensional systems.

Chiral State Conversion in a Levitated Micromechanical Oscillator with In Situ Control of Parameter Loops

Physical systems with gain and loss can be described by a non-Hermitian Hamiltonian,which is degenerated at the exceptional points(EPs).Many new and unexpected features have been explored in the non-Hermitian systems with a great deal of recent interest.One of the most fascinating features is that chiral state conversion appears when one EP is encircled dynamically.Here,we propose an easy-controllable levitated microparticle system that carries a pair of EPs and realize slow evolution of the Hamiltonian along loops in the parameter plane.Utilizing the controllable rotation angle,gain and loss coefficients,we can control the structure,size and location of the loops in situ.We demonstrate that,under the joint action of topological structure of energy surfaces and nonadiabatic transitions,the chiral behavior emerges both along a loop encircling an EP and even along a straight path away from the EP.This work broadens the range of parameter space for the chiral state conversion,and proposes a useful platform to explore the interesting properties of exceptional points physics.

Pulse-width-induced polarization enhancement of optically pumped N-V electron spin in diamond

The nitrogen-vacancy(N-V)center in diamond is a widely used platform for quantum information processing and sensing.The electron-spin state of the N-V center could be initialized,read out optically,and manipulated by resonate microwave fields.In this work,we analyze the dependence of electron-spin initialization on widths of laser pulses.We build a numerical model to simulate this process and to verify the simulation results in experiments.Both simulations and experiments reveal that shorter laser pulses are helpful to the electron-spin polarization.We therefore propose to use extremely short laser pulses for electron-spin initialization.In this new scheme,the spin-state contrast could be improved about 10%in experiments by using laser pulses as short as 4 ns in width.Furthermore,we provide a mechanism to explain this effect,which is due to the occupation time in the meta-stable spin-singlet states of the N-V center.Our new scheme is applicable in a broad range of N-V-based applications in the future.

Identification and optimization of peptide inhibitors to block VISTA/PSGL-1 interaction for cancer immunotherapy

Developing new therapeutic agents for cancer immunotherapy is highly demanding due to the low response ratio of PD-1/PD-L1 blockade in cancer patients.Here,we discovered that the novel immune checkpoint VISTA is highly expressed on a variety of tumor-infiltrating immune cells,especially myeloid derived suppressor cells(MDSCs)and CD8^(+)T cells.Then,peptide C1 with binding affinity to VISTA was developed by phage displayed bio-panning technique,and its mutant peptide VS3 was obtained by molecular docking based mutation.Peptide VS3 could bind VISTA with high affinity and block its interaction with ligand PSGL-1 under acidic condition,and elicit anti-tumor activity in vivo.The peptide DVS3-Pal was further designed by D-amino acid substitution and fatty acid modification,which exhibited strong proteolytic stability and significant anti-tumor activity through enhancing CD8^(+)T cell function and decreasing MDSCs infiltration.This is the first study to develop peptides to block VISTA/PSGL-1 interaction,which could act as promising candidates for cancer immunotherapy.

Direct characteristic-function tomography of the quantum states of quantum fields

Herein,we propose a novel strategy for implementing a direct readout of the symmetric characteristic function of the quantum states of quantum fields without the involvement of idealized measurements,an aspect that has always been deemed ill-defined in quantum field theory.This proposed scheme relies on the quantum control and measurements of an auxiliary qubit locally coupled to the quantum fields.By mapping the expectation values of both the real and imaginary parts of the field displacement operator to the qubit states,the qubit's readout provides complete information regarding the symmetric characteristic function.We characterize our technique by applying it to the Kubo-Martin-Schwinger(thermal)and squeezed states of a quantum scalar field.In addition,we have discussed general applications of this approach to analogue-gravity systems,such as Bose-Einstein condensates,within the scope of state-of-the-art experimental capabilities.This proposed strategy may serve as an essential in understanding and optimizing the control of quantum fields for relativistic quantum information applications,particularly in exploring the interplay between gravity and quantum,for example,the relation to locality,causality,and information.

Blocking of the PD-1/PD-L1 interaction by a novel cyclic peptide inhibitor for cancer immunotherapy

The interaction of PD-1/PD-L1 allows tumor cells to escape from immune surveillance.Clinical success of the antibody drugs has proven that blockade of PD-1/PD-L1 pathway is a promising strategy for cancer immunotherapy.Here,we developed a cyclic peptide C8 by using Ph.D.-C7 C phage display technology.C8 showed high binding affinity with h PD-1 and could effectively interfere the interaction of PD-1/PD-L1.Furthermore,C8 could stimulate CD8^(+)T cell activation in human peripheral blood mononuclear cells(PBMCs).We also observed that C8 could suppress tumor growth in CT26 and B16-OVA,as well as anti-PD-1 antibody resistant B16 mouse model.CD8^(+)T cells infiltration significantly increased in tumor microenvironment,and IFN-γsecretion by CD8^(+)T cells in draining lymph nodes also increased.Simultaneously,we exploited T cells depletion models and confirmed that C8 exerted anti-tumor effects via activating CD8^(+)T cells dependent manner.The interaction model of C8 with h PD-1 was simulated and confirmed by alanine scanning.In conclusion,C8 shows anti-tumor capability by blockade of PD-1/PD-L1 interaction,and C8 may provide an alternative candidate for cancer immunotherapy.

A hybrid magnetometer towards femtotesla sensitivity under ambient conditions

Detecting magnetic field is of great importance for many applications,such as magnetoencephalography and underground prospecting.There have been many magnetometers being widely used since the age of Hall magnetometer.One of the magnetometers,the superconducting quantum interference device,is capable of measuring femtotesla magnetic fields at cryogenic temperature.However,a solid-state magnetometer with femtotesla sensitivity under ambient conditions remains elusive.Here we present a hybrid magnetometer based on the ensemble nitrogen-vacancy centers in diamond with the sensitivity of(195±60)fT/Hz^(1/2)under ambient conditions,which can be further advanced to 11 fT/Hz^(1/2)at 100 Hz with cutting-edge fabrication technologies.Our method will find potential applications in biomagnetism and geomagnetism.

Detection of radio-frequency field with a single spin in diamond

Detection of a.c. magnetic field is consequential for many developments in physical and biological sciences,and various designs of magnetometer have been proposed recently. However, the large size of sensor and the extreme measurement conditions required strongly limit their application. It remains a challenge to reconstruct the vector of a.c. field with nanoscale spatial resolution using a single spin under ambient conditions. In this work, we choose the radio-frequency(RF) field as a typical case and realize the measurement of RF field based on a nitrogen-vacancy(NV)center in diamond. We build a solid sensor through measuring the effect of RF field on NV electron spin energy levels and the transition between them. Both of the phase and amplitude(including the transverse and longitudinal components) are measured by this new approach.

3D structural modeling integrated with seismic attribute and petrophysical evaluation for hydrocarbon prospecting at the Dhulian Oilfield,Pakistan

Surface and deep subsurface geological structural trends,stratigraphic features,and reservoir characteristics play important roles in assessment of hydrocarbon potential.Here,an approach that integrates digital elevation modelling,seismic interpretation,seismic attributes,three-dimensional(3D)geological structural modeling predicated on seismic data interpretation,and petrophysical analysis is presented to visualize and analyze reservoir structural trends and determine residual hydrocarbon potential.The digital elevation model is utilized to provide verifiable predictions of the Dhulian surface structure.Seismic interpretation of synthetic seismograms use two-way time and depth contour models to perform a representative 3D reservoir geological structure evaluation.Based on Petrel structural modeling efficiency,reservoir development indexes,such as the true 3D structural trends,slope,geometry type,depth,and possibility of hydrocarbon prospects,were calculated for the Eocene limestone Chorgali,upper Paleocene limestone Lockhart,early Permian arkosic sandstone Warcha,and Precambrian Salt Range formations.Trace envelope,instantaneous frequency,and average energy attribute analyses were utilized to resolve the spatial predictions of the subsurface structure,formation extrusion,and reflector continuity.We evaluated the average porosity,permeability,net to gross ratio,water saturation,and hydrocarbon saturation of early Eocene limestone and upper Paleocene limestone based on the qualitative interpretation of well log data.In summary,this integrated study validates 3D stratigraphic structural trends and fault networks,facilitates the residual hydrocarbon potential estimates,and reveals that the Dhulian area has a NE to SW(fold axis)thrust-bounded salt cored anticline structure,which substantiates the presence of tectonic compression.The thrust faults have fold axes trending from ENE to WSW,and the petrophysical analysis shows that the mapped reservoir is of good quality and has essential hydrocarbon potential,which can be exploited economically.

Experimental preparation of topologically ordered states via adiabatic evolution

Topological orders are a class of exotic states of matter characterized by patterns of long-range entanglement. Certain topologically ordered systems are proposed as potential realization of fault-tolerant quantum computation. Topological orders can arise in two-dimensional spin-lattice models. In this paper, we engineer a time-dependent Hamiltonian to prepare a topologically ordered state through adiabatic evolution. The other sectors in the degenerate ground-state space of the model are obtained by applying nontrivial operations corresponding to closed string operators. Each sector is highly entangled, as shown from the completely reconstructed density matrices. This paves the way towards exploring the properties of topological orders and the application of topological orders in topological quantum memory.