查看更多>>摘要：Reducing the control error is vital for high-fidelity digital and analog quantum operations.In superconducting circuits,one disagreeable error arises from the reflection of microwave signals due to impedance mismatch in the control chain.Here,we demonstrate a reflection cancelation method when considering that there are two reflection nodes on the control line.We propose to generate the pre-distortion pulse by passing the envelopes of the microwave signal through digital filters,which enables real-time reflection correction when integrated into the field-programmable gate array(FPGA).We achieve a reduction of single-qubit gate infidelity from 0.67％to 0.11％after eliminating microwave reflection.Real-time correction of microwave reflection paves the way for precise control and manipulation of the qubit state and would ultimately enhance the performance of algorithms and simulations executed on quantum processors.
查看更多>>摘要：One-way quantum computation focuses on initially generating an entangled cluster state followed by a sequence of measurements with classical communication of their individual outcomes.Recently,a delayed-measurement approach has been applied to replace classical communication of individual measurement outcomes.In this work,by considering the delayed-measurement approach,we demonstrate a modified one-way CNOT gate using the on-cloud superconducting quantum computing platform:Quafu.The modified protocol for one-way quantum computing requires only three qubits rather than the four used in the standard protocol.Since this modified cluster state decreases the number of physical qubits required to implement one-way computation,both the scalability and complexity of the computing process are improved.Compared to previous work,this modified one-way CNOT gate is superior to the standard one in both fidelity and resource requirements.We have also numerically compared the behavior of standard and modified methods in large-scale one-way quantum computing.Our results suggest that in a noisy intermediate-scale quantum(NISQ)era,the modified method shows a significant advantage for one-way quantum computation.
查看更多>>摘要：The performance of Nb superconducting quantum devices is predominantly limited by dielectric loss at the metal-air interface,where Nb2O5 is considered the main loss source.Here,we suppress the formation of native oxides by in-situ deposition of a TiN capping layer on the Nb film.With TiN capping layers,no Nb2O5 forms on the surface of the Nb film.The quality factor Qi of the Nb resonator increases from 5.6 × 105 to 7.9 × 105 at low input power and from 6.8 × 106 to 1.1 × 107 at high input power.Furthermore,the TiN capping layer also shows good aging resistance in Nb resonator devices,with no significant performance fluctuations after one month of aging.These findings highlight the effectiveness of TiN capping layers in enhancing the performance and longevity of Nb superconducting quantum devices.
查看更多>>摘要：Scaling up spin qubits in silicon-based quantum dots is one of the pivotal challenges in achieving large-scale semi-conductor quantum computation.To satisfy the connectivity requirements and reduce the lithographic complexity,utilizing the qubit array structure and the circuit quantum electrodynamics(cQED)architecture together is expected to be a feasible scaling scheme.A triple-quantum dot(TQD)coupled with a superconducting resonator is regarded as a basic cell to demon-strate this extension scheme.In this article,we investigate a system consisting of a silicon TQD and a high-impedance TiN coplanar waveguide(CPW)resonator.The TQD can couple to the resonator via the right double-quantum dot(RDQD),which reaches the strong coupling regime with a charge-photon coupling strength of go/(2π)=175 MHz.Moreover,we illustrate the high tunability of the TQD through the characterization of stability diagrams,quadruple points(QPs),and the quantum cellular automata(QCA)process.Our results contribute to fostering the exploration of silicon-based qubit integration.
查看更多>>摘要：Kagome magnets were predicted to be a good platform to investigate correlated topology band structure,Chern quantum phase,and geometrical frustration due to their unique lattice geometry.Here we reported single crystal growth of 166-type kagome magnetic materials,including HfMn6Sn6,ZrMn6Sn6,GdMn6Sn6 and GdV6Sn6,by using the flux method with Sn as the flux.Among them,HfMn6Sn6 and ZrMn6Sn6 single crystals were grown for the first time.X-ray diffraction measurements reveal that all four samples crystallize in HfFe6Ge6-type hexagonal structure with space group P6/mmm.All samples show metallic behavior from temperature dependence of resistivity measurements,and the dom-inant carrier is hole,except for GdV6Sn6 which is electron dominated.All samples have magnetic order with different transition temperatures,HfMn6Sn6,ZrMn6Sn6 and GdV6Sn6 are antiferromagnetic with TN of 541 K,466 K and 4 K respectively,while GdMn6Sn6 is ferrimagnetic with the critical temperature of about 470 K.This study will enrich the research platform of magnetic kagome materials and help explore the novel quantum phenomena in these interesting mate-rials.The dataset of specific crystal structure parameters for HfMn6Sn6 are available in Science Data Bank,with the link https://doi.org/10.57760/sciencedb.j00113.00120.
查看更多>>摘要：Laser absorption spectroscopy has proven to be an effective approach for gas sensing,which plays an important role in the fields of military,industry,medicine and basic research.This paper presents a multiplexed gas sensing system based on optical frequency comb(OFC)calibrated frequency-modulated continuous-wave(FMCW)tuning nonlinearity.The system can be used for multi-parameter synchronous measurement of gas absorption spectrum and multiplexed optical path.Multi-channel parallel detection is realized by combining wavelength division multiplexing(WDM)and frequency division multiplexing(FDM)techniques.By introducing nonlinear optical crystals,broadband spectrum detection is simul-taneously achieved over a bandwidth of hundreds of nanometers.An OFC with ultra-high frequency stability is used as the frequency calibration source,which guarantees the measurement accuracy.The test samples involve H13C14N,C2H2 and Rb vapor cells of varying densities and 5 parallel measurement experiments are designed.The results show that the measurement accuracies of spectral absorption line and the optical path are 150 MHz and 20 μm,respectively.The scheme offers the advantages of multiplexed,multi-parameter,wide spectrum and high resolution detection,which can realize the identification of multi-gas components and the high-precision inversion of absorption lines under different environments.The proposed sensor demonstrates great potential in the field of high-resolution absorption spectrum measurement for gas sensing applications.
查看更多>>摘要：Diamond has an ultrawide bandgap with excellent physical properties,such as high critical electric field,excellent thermal conductivity,high carrier mobility,etc.Diamond with a hydrogen-terminated(H-terminated)surface has a negative electron affinity(NEA)and can easily produce surface electrons from valence or trapped electrons via optical absorption,thermal heating energy or carrier transport in a PN junction.The NEA of the H-terminated surface enables surface electrons to emit with high efficiency into the vacuum without encountering additional barriers and promotes further development and application of diamond-based emitting devices.This article reviews the electron emission properties of H-terminated diamond surfaces exhibiting NEA characteristics.The electron emission is induced by different physical mechanisms.Recent advancements in electron-emitting devices based on diamond are also summarized.Finally,the current challenges and future development opportunities are discussed to further develop the relevant applications of diamond-based electron-emitting devices.
查看更多>>摘要：Levitated optomechanical systems represent an excellent candidate platform for force and acceleration sensing.We propose a force-sensing protocol utilizing an optically levitated nanoparticle array.In our scheme,N nanoparticles are trapped in an optical cavity using holographic optical tweezers.An external laser drives the cavity,exciting N cavity modes interacting simultaneously with the N nanoparticles.The optomechanical interaction encodes the information of the force acting on each nanoparticle onto the intracavity photons,which can be detected directly at the output ports of the cavity.Consequently,our protocol enables real-time imaging of a force field.
查看更多>>摘要：Coexistence of ferromagnetism and ferroelasticity in a single material is an intriguing phenomenon,but has been rarely found.Here we studied both the ferromagnetism and ferroelasticity in a group of LaCoO3 films with systematically tuned atomic structures.We found that all films exhibit ferroelastic domains with four-fold symmetry and the larger domain size(higher elasticity)is always accompanied by stronger ferromagnetism.We performed synchrotron x-ray diffraction studies to investigate the backbone structure of the CoO6 octahedra,and found that both the ferromagnetism and the elasticity are simultaneously enhanced when the in-plane Co-O-Co bond angles are straightened.Therefore the study demonstrates the inextricable correlation between the ferromagnetism and ferroelasticity mediated through the octahedral backbone structure,which may open up new possibilities to develop multifunctional materials.
查看更多>>摘要：Unconventional antiferromagnetism dubbed as altermagnetism was first discovered in rutile structured magnets,which is featured by spin splitting even without the spin-orbital coupling effect.This interesting phenomenon has been discovered in more altermagnetic materials.In this work,we explore two-dimensional altermagnetic materials by studying two series of two-dimensional magnets,includingMF4with M covering all 3d and 4d transition metal elements,as well as TS2 with T=V,Cr,Mn,Fe.Through the magnetic symmetry operation of RuF4 and MnS2,it is verified that breaking the time inversion is a necessary condition for spin splitting.Based on symmetry analysis and first-principles calculations,we find that the electronic bands and magnon dispersion experience alternating spin splitting along the same path.This work paves the way for exploring altermagnetism in two-dimensional materials.
NETL
NSTL
万方数据