Recently,large-scale trapped ion systems have been realized in experiments for quantum simulation and quantum computation.They are the simplest systems for dynamical stability and parametric resonance.In this model,th...Recently,large-scale trapped ion systems have been realized in experiments for quantum simulation and quantum computation.They are the simplest systems for dynamical stability and parametric resonance.In this model,the Mathieu equation plays the most fundamental role for us to understand the stability and instability of a single ion.In this work,we investigate the dynamics of trapped ions with the Coulomb interaction based on the Hamiltonian equation.We show that the many-body interaction will not influence the phase diagram for instability.Then,the dynamics of this model in the large damping limit will also be analytically calculated using few trapped ions.Furthermore,we find that in the presence of modulation,synchronization dynamics can be observed,showing an exchange of velocities between distant ions on the left side and on the right side of the trap.These dynamics resemble that of the exchange of velocities in Newton's cradle for the collision of balls at the same time.These dynamics are independent of their initial conditions and the number of ions.As a unique feature of the interacting Mathieu equation,we hope this behavior,which leads to a quasi-periodic solution,can be measured in current experimental systems.Finally,we have also discussed the effect of anharmonic trapping potential,showing the desynchronization during the collision process.It is hoped that the dynamics in this many-body Mathieu equation with damping may find applications in quantum simulations.This model may also find interesting applications in dynamics systems as a pure mathematical problem,which may be beyond the results in the Floquet theorem.展开更多
In the lattice system,when the synthetic flux reaches aπphase along a closed loop under the synthetic gauge field,destructive interference occurs and gives rise to the localization phenomenon.This is known as the Aha...In the lattice system,when the synthetic flux reaches aπphase along a closed loop under the synthetic gauge field,destructive interference occurs and gives rise to the localization phenomenon.This is known as the Aharonov-Bohm(AB)caging effect.It provides a powerful tool for the study of quantum transport and dynamical effects.In the system where lattice sites possess internal structure and the underlying gauge field is non-Abelian,localization can also occur,forming the non-Abelian AB caging.Here,we propose an experimental scheme to synthesize non-Abelian gauge fields with a single trapped ion by coupling multiple internal levels and Fock states in its motion via laser fields.In contrast to the Abelian AB caging,we numerically observe that the non-Abelian AB caging occurs either when the interference matrix is nilpotent,or when the initial state is specifically set.Our experimental scheme broadens the study of localization phenomena and provides a novel tool for the study of non-Abelian physics.展开更多
Trapped ion hardware has made significant progress recently and is now one of the leading platforms for quantum computing.To construct two-qubit gates in trapped ions,experimentalmanipulation approaches for ion chains...Trapped ion hardware has made significant progress recently and is now one of the leading platforms for quantum computing.To construct two-qubit gates in trapped ions,experimentalmanipulation approaches for ion chains are becoming increasingly prevalent.Given the restricted control technology,how implementing high-fidelity quantum gate operations is crucial.Many works in current pulse design optimization focus on ion–phonon and effective ion–ion couplings while ignoring the first-order derivative terms expansion impacts of these two terms brought on by experiment defects.This paper proposes a novel robust quantum control optimization method in trapped ions.By introducing the first-order derivative terms caused by the error into the optimization cost function,we generate an extremely robust Mølmer–Sørensen gate with infidelity below 10^(−3) under a drift noise range of±10 kHz,the relative robustness achieves a tolerance of±5%,compared to the 200-kHz frequency spacing between phonon modes,and for time noise drift,the tolerance reached to 2%.Our work reveals the vital role of the first-order derivative terms of coupling in trapped ion pulse control optimization,especially the first-order derivative terms of ion–ion coupling.It provides a robust optimization scheme for realizing more efficient entangled states in trapped ion platforms.展开更多
Trapped-ion systems are one of the leading platforms for quantum information processing, where a key challenge is to scale up system size while maintaining high-fidelity two-qubit operations. A promising approach is t...Trapped-ion systems are one of the leading platforms for quantum information processing, where a key challenge is to scale up system size while maintaining high-fidelity two-qubit operations. A promising approach is to build high-performance modules interconnected via strong coupling. In particular, axial motional modes offer a practical mechanism to couple the ions in a chain, enabling the preparation of Greenberger–Horne–Zeilinger states with up to 24 ions using global operations, as well as high-fidelity two-qubit gates(96.6%–98.0%) in fully connected five-ion chains. Here, we demonstrate two-qubit quantum logic gates in a 5-ion^(40)Ca^(+)chain using axial modes, achieving fidelities exceeding 99% for adjacent pairs and over 98% for arbitrary pairs by carefully tackling dominant error sources. Our results are beneficial to the development of scalable ion-trap quantum processors,quantum simulation and quantum-enhanced metrology.展开更多
This article is to review results from scientific drilling and fault-zone trapped waves （FZTWs） at the south Longman-Shan fault （LSF） zone that ruptured in the 2008 May 12 M8 Wenchuan earthquake in Sichuan,China.I...This article is to review results from scientific drilling and fault-zone trapped waves （FZTWs） at the south Longman-Shan fault （LSF） zone that ruptured in the 2008 May 12 M8 Wenchuan earthquake in Sichuan,China.Immediately after the mainshock,two Wenchuan Fault Scientific Drilling （WFSD） boreholes were drilled at WFSD-1 and WFSD-2 sites approximately 400 m and 1 km west of the surface rupture along the Yinxiu-Beichuan fault （YBF）,the middle fault strand of the south LSF zone.Two boreholes met the principal slip of Wenchuan earthquake along the YBF at depths of 589-m and 1230-m,respectively.The slip is accompanied with a 100-200-m-wide zone consisting of fault gouge,breccia,cataclasite and fractures.Close to WFSD-1 site,the nearly-vertical slip of ～4.3-m with a 190-m wide zone of highly fractured rocks restricted to the hanging wall of the YBF was found at the ground surface after the Wenchuan earthquake.A dense linear seismic array was deployed across the surface rupture at this venue to record FZTWs generated by aftershocks.Observations and 3-D finite-difference simulations of FZTWs recorded at this cross-fault array and network stations close to the YBF show a distinct low-velocity zone composed by severely damaged rocks along the south LSF at seismogenic depths.The zone is several hundred meters wide along the principal slip,within which seismic velocities are reduced by ～30-55％ from wall-rock velocities and with the maximum velocity reduction in the ～200-m-wide rupture core zone at shallow depth.The FZTW-inferred geometry and physical properties of the south LSF rupture zone at shallow depth are in general consistent with the results from petrological and structural analyses of cores and well log at WFSD boreholes.We interpret this remarkable low-velocity zone as being a break-down zone during dynamic rupture in the 2008 M8 earthquake.We examined the FZTWS generated by similar earthquakes before and after the 2008 mainshock and observed that seismic velocities within fault core zone was reduced by ～10％ due to severe damage of fault rocks during the M8 mainshock.Scientific drilling and locations of aftershocks generating prominent FZTWs also indicate rupture bifurcation along the YBF and the Anxian-Guangxian fault （AGF）,two strands of the south LSF at shallow depth.A combination of seismic,petrologic and geologic study at the south LSF leads to further understand the relationship between the fault-zone structure and rupture dynamics,and the amplification of ground shaking strength along the low-velocity fault zone due to its waveguide effect.展开更多
The rupture process of the May 12, 2008 Ms8.0 Wenchuan earthquake was very complex. To study the rupture zones generated by this earthquake, four dense temporary seismic arrays across the two surface breaking traces o...The rupture process of the May 12, 2008 Ms8.0 Wenchuan earthquake was very complex. To study the rupture zones generated by this earthquake, four dense temporary seismic arrays across the two surface breaking traces of the main-shock were deployed in July and recorded a great amount of aftershocks. This paper focuses on the data interpretation of two arrays across the central main fault, the northern array line 1 and southern array line 3. The fault zone trapped waves recorded by the two arrays were used to study the structure of the central main fault and the difference between the northern and southern portions. The results show that the widths of the rupture zone are about 170-200 m and 200-230 m for northern and southern portions respectively. And the corresponding dip angles are 80° and 70°. The seismic velocity inside the fracture zone is about one half of the host rock. By comparison, the northern portion of the rupture zone is slightly narrower and steeper than the southern portion. Besides these differences, one more interesting and important difference is the positions of the rupture zone with respect to surface breaking traces. At the northern portion, the rupture zone is centered at the surface breaking trace, while at the southern portion it is not but is shifted to the northwest. This difference reflects the difference of rupture behaviors between two portions of the central main fault. The width of the rupture zone is smaller than that of MS.1 Kunlun earthquake though these two earthquakes have almost the same magnitudes. Multiple ruptures may be one factor to cause the narrower rupture zone.展开更多
Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportio...Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor. Due to the presence of entrainment phenomenon, the total air flow in the cavity zone is difficult to estimate. To overcome the measurement difficulty, this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity. In accordance with the measurement principle, a TVC model fueled by methane is designed. Under two experimental conditions, i.e. with and without direct air intake in the cavity, the influence of the mainstream air flow velocity, the air intake velocity in the cavity, the height of inlet channel, the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied, respectively, through experiment at atmospheric temperature and pressure. The results suggest that the air flow velocity of mainstream, the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment, while the influence of structural proportion of the cavity is comparatively insignificant. The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.展开更多
The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersio...The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersion relation is obtained analytically by means of the modified lens-type transformation and linear stability analysis.It is shown that a modulational unstable time scale exists for trapped two-component BECs.The modulational properties-which are determined by the wave number,external trapping parameter,intraand inter-species atomic interactions-are modified significantly.The analytical results are confirmed by direct numerical simulation.Our results provide a criterion for judging the occurrence of instability of the trapped two-component BECs in experiment.展开更多
An effective teleportation scheme for an unknown ionic internal state via trapped ions is proposed without joint Bell-state measurement （BSM）. In the constructed quantum channel process, we make use of entanglement ...An effective teleportation scheme for an unknown ionic internal state via trapped ions is proposed without joint Bell-state measurement （BSM）. In the constructed quantum channel process, we make use of entanglement swapping to avoid decrease in entanglement during the distributing of particles. Thus our scheme provides new prospects for quantum teleportatlon in a longer distance. The distinct advant.age of our scheme is insensitive to the heating of vibrational mode. Furthermore, our scheme has no any individual optical access, and the successful probability also can reach 1.展开更多
To evaluate the trapped wave energy and energy loss, the problem of wave scattering by twin fixed vertical surface- piercing plates over a stepped bottom is numerically simulated using the open source package OpenFOAM...To evaluate the trapped wave energy and energy loss, the problem of wave scattering by twin fixed vertical surface- piercing plates over a stepped bottom is numerically simulated using the open source package OpenFOAM and the associated toolbox waves2Foam. The volume of fluid (VOF) method was employed to capture the free surface in the time domain. The validation of the present numerical model was performed by comparing with both the analytical and experimental results. The effects of the spacing between two plates and the configuration of stepped bottom on the hydrodynamic characteristics, such as reflection and transmission coefficients, viscous dissipation ratio, and relative wave height between the plates (termed as trapped wave energy), were examined. Moreover, the nonlinear effects of the incident wave height on the hydrodynamic characteristics were addressed as well. The results show that the step configuration can be tuned for efficient-performance of wave damping, and the optimum configurations of the step length B, the step height h1 and the spacing b, separately equaling λ/4, 3h/4, and 0.05h (λ and h are the wavelength and the water depth, respectively), are recommended for the trapping of wave energy.展开更多
This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quant...This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity during the preparation for a four-atom entangled cluster state, and thus the scheme is insensitive to the cavity field states and cavity decay. Assuming that deviation of laser intensity is 0.01 and that of simultaneity for the interaction is 0.01, it shows that the fidelity of the resulting four-atom entangled cluster state is about 0.9886. The scheme can also be used to generate a four-ion entangled cluster state in a hot trapped-ion system. Assuming that deviation of laser intensity is 0.01, it shows that the fidelity of the resulting four-ion entangled cluster state is about 0.9990. Experimental feasibility for achieving this scheme is also discussed.展开更多
This paper considers a scheme for the preparation of two-qutrit entangled states via adiabatic passage in iontrapped system. In the proposal, the two three-level V-type ions are initially cooled to the ground states a...This paper considers a scheme for the preparation of two-qutrit entangled states via adiabatic passage in iontrapped system. In the proposal, the two three-level V-type ions are initially cooled to the ground states and need not be separately addressed. Moreover, only the ionic states act as memory and the system evolves in the dark space during the whole procedure, which makes the system robust against the decoherence and the fluctuation of the laser pulse.展开更多
We propose a scheme to generate entangled coherent states for the vibrational modes of N trapped ions.In the scheme the first ion is sequentially excited by two travelling wave laser fields tuned to the ion transition...We propose a scheme to generate entangled coherent states for the vibrational modes of N trapped ions.In the scheme the first ion is sequentially excited by two travelling wave laser fields tuned to the ion transition. The scheme works in the strong-excitation regime, which is of experimental importance in view of decoherence.展开更多
A trapped vortex combustor （TVC） has been a very promising novel concept for it offers improvements in lean blow out, altitude relight, operating range, as well as a potential to decrease NOx emissions compared to c...A trapped vortex combustor （TVC） has been a very promising novel concept for it offers improvements in lean blow out, altitude relight, operating range, as well as a potential to decrease NOx emissions compared to conventional combustors. The present paper discusses the improved designs of the new combustor over the prior ones of our research group, including that：a） the over-all dimensions, both axial and radial, are reduced to those of an actual aero-engine combustor; b） the air flow distribution is optimized, and especially 15% of the air is fed into the liner as cooling air; c） a straight-wall diffuser with divergence angle 9°is added. A series of experiments （cavity-fueled only, under atmospheric pressure） has been conducted to investigate the performance of the improved TVC. Experimental results show that at the inlet temperature of 523 K, the inlet pressure of 0.1 MPa, stable operation of the TVC test rig is observed for the Mach number 0.15-0.34, indicating good flame stability; the combustion efficiency obtained in this paper falls into the range of 60%-96%; as the total excess air ratio increases, the combustion efficiency decreases, while the increase of the inlet temperature is beneficial to high combustion efficiency; besides, the optimal Mach numbers for high combustion efficiency under different inlet conditions are confirmed. The outlet temperature profiles feature a bottom in the midheight of the exit. This paper demonstrates the feasibility for the TVC to be applied to a realistic aero-engine preliminarily and provides reference for TVC design.展开更多
Trapped waves in the Qingchuan fault zone were observed at Muyu near the northeastern end of the fractured zone of the Wenchuan Ms8. 0 earthquake. The results indicate a fault-zone width of about 200 m and a great dif...Trapped waves in the Qingchuan fault zone were observed at Muyu near the northeastern end of the fractured zone of the Wenchuan Ms8. 0 earthquake. The results indicate a fault-zone width of about 200 m and a great difference in physical property of the crust on different sides of the fault. The inferred location of crustal changes is consistent with land-form boundary on the surface展开更多
In this paper, we apply an unstructured grid coastal ocean model to simulate variations in the sea level and currents forced by two typhoons in the northwestern South China Sea(SCS). The model simulations show distinc...In this paper, we apply an unstructured grid coastal ocean model to simulate variations in the sea level and currents forced by two typhoons in the northwestern South China Sea(SCS). The model simulations show distinct differences for the two cases in which the typhoon paths were north and south of the Qiongzhou(QZ) Strait. In both cases, coastal trapped waves(CTWs) are stimulated but their propagation behaviors differ. Model sensitivity simulations suggest the dominant role played by alongshore wind in the eastern SCS(near Shanwei) and southeast of Hainan Island. We also examine the influence of the Leizhou Peninsula by changing the coastline in simulation experiments. Based on our results, we can draw the following conclusions: 1) The CTWs stimulated by the northern typhoon are stronger than the southern CTW. 2) In the two cases, the directions of the current structures of the QZ cross-transect are reversed. The strongest flow cores are both located in the middle-upper area of the strait and the results of our empirical orthogonal function analysis show that the vertical structure is highly barotropic. 3) The simulated CTWs divide into two branches in the QZ Strait for the northern typhoon, and an island trapped wave(ITW) around Hainan Island for the southern typhoon. 4) The Leizhou Peninsula plays a significant role in the distribution of the kinetic energy flux between the two CTW branches. In the presence of the Leizhou Peninsula, the QZ branch has only 39.7 percent of the total energy, whereas that ratio increases to 72.2 percent in its absence.展开更多
In this article,we review our previous research for spatial and temporal characterizations of the San Andreas Fault(SAF)at Parkfield,using the fault-zone trapped wave(FZTW)since the middle 1980s.Parkfield,California h...In this article,we review our previous research for spatial and temporal characterizations of the San Andreas Fault(SAF)at Parkfield,using the fault-zone trapped wave(FZTW)since the middle 1980s.Parkfield,California has been taken as a scientific seismic experimental site in the USA since the 1970s,and the SAF is the target fault to investigate earthquake physics and forecasting.More than ten types of field experiments(including seismic,geophysical,geochemical,geodetic and so on)have been carried out at this experimental site since then.In the fall of 2003,a pair of scientific wells were drilled at the San Andreas Fault Observatory at Depth(SAFOD)site;the main-hole(MH)passed a~200-m-wide low-velocity zone(LVZ)with highly fractured rocks of the SAF at a depth of~3.2 km below the wellhead on the ground level(Hickman et al.,2005;Zoback,2007;Lockner et al.,2011).Borehole seismographs were installed in the SAFOD MH in 2004,which were located within the LVZ of the fault at~3-km depth to probe the internal structure and physical properties of the SAF.On September 282004,a M6 earthquake occurred~15 km southeast of the town of Parkfield.The data recorded in the field experiments before and after the 2004 M6 earthquake provided a unique opportunity to monitor the co-mainshock damage and post-seismic heal of the SAF associated with this strong earthquake.This retrospective review of the results from a sequence of our previous experiments at the Parkfield SAF,California,will be valuable for other researchers who are carrying out seismic experiments at the active faults to develop the community seismic wave velocity models,the fault models and the earthquake forecasting models in global seismogenic regions.展开更多
A method of solving an ultracold trapped ion at the node of the standing wave laser without rotating wave approximation is proposed and the analytical forms of the eigenfunctions and eigenenergies of the system are pr...A method of solving an ultracold trapped ion at the node of the standing wave laser without rotating wave approximation is proposed and the analytical forms of the eigenfunctions and eigenenergies of the system are presented.展开更多
We propose a scheme for the preparation of one-dimensional and two-dimensional cluster states by using hot trapped ions. The scheme is based on the interaction between two ions and bichromatic radiation. The vibration...We propose a scheme for the preparation of one-dimensional and two-dimensional cluster states by using hot trapped ions. The scheme is based on the interaction between two ions and bichromatic radiation. The vibrational mode in our protocol is only virtually excited so that the system is insensitive to the thermal field. In addition, we only use two levels of ions as qubits and the successful probability may achieve 100%.展开更多
Beyond the Lamb-Dicke limit, this paper investigates the squeezing properties of the trapped ion in the travelling- wave laser. It shows that the squeezing properties of the trapped ion in the travelling-wave laser ar...Beyond the Lamb-Dicke limit, this paper investigates the squeezing properties of the trapped ion in the travelling- wave laser. It shows that the squeezing properties of the trapped ion in the travelling-wave laser are strongly affected by the sideband number k, the Lamb-Dicke parameter η and the initial average phonon number.展开更多
基金supported by the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0301200,2021ZD0303200,and 2021ZD0301500)the Alliance of International Science Organizations(ANSO)。
文摘Recently,large-scale trapped ion systems have been realized in experiments for quantum simulation and quantum computation.They are the simplest systems for dynamical stability and parametric resonance.In this model,the Mathieu equation plays the most fundamental role for us to understand the stability and instability of a single ion.In this work,we investigate the dynamics of trapped ions with the Coulomb interaction based on the Hamiltonian equation.We show that the many-body interaction will not influence the phase diagram for instability.Then,the dynamics of this model in the large damping limit will also be analytically calculated using few trapped ions.Furthermore,we find that in the presence of modulation,synchronization dynamics can be observed,showing an exchange of velocities between distant ions on the left side and on the right side of the trap.These dynamics resemble that of the exchange of velocities in Newton's cradle for the collision of balls at the same time.These dynamics are independent of their initial conditions and the number of ions.As a unique feature of the interacting Mathieu equation,we hope this behavior,which leads to a quasi-periodic solution,can be measured in current experimental systems.Finally,we have also discussed the effect of anharmonic trapping potential,showing the desynchronization during the collision process.It is hoped that the dynamics in this many-body Mathieu equation with damping may find applications in quantum simulations.This model may also find interesting applications in dynamics systems as a pure mathematical problem,which may be beyond the results in the Floquet theorem.
基金supported by the National Natural Science Foundation of China(Grant Nos.92165206,12275090,and 12304554)the Innovation Program for Quantum Science and Technology(Grant Nos.2021ZD0301603 and 2021ZD0302303)。
文摘In the lattice system,when the synthetic flux reaches aπphase along a closed loop under the synthetic gauge field,destructive interference occurs and gives rise to the localization phenomenon.This is known as the Aharonov-Bohm(AB)caging effect.It provides a powerful tool for the study of quantum transport and dynamical effects.In the system where lattice sites possess internal structure and the underlying gauge field is non-Abelian,localization can also occur,forming the non-Abelian AB caging.Here,we propose an experimental scheme to synthesize non-Abelian gauge fields with a single trapped ion by coupling multiple internal levels and Fock states in its motion via laser fields.In contrast to the Abelian AB caging,we numerically observe that the non-Abelian AB caging occurs either when the interference matrix is nilpotent,or when the initial state is specifically set.Our experimental scheme broadens the study of localization phenomena and provides a novel tool for the study of non-Abelian physics.
文摘Trapped ion hardware has made significant progress recently and is now one of the leading platforms for quantum computing.To construct two-qubit gates in trapped ions,experimentalmanipulation approaches for ion chains are becoming increasingly prevalent.Given the restricted control technology,how implementing high-fidelity quantum gate operations is crucial.Many works in current pulse design optimization focus on ion–phonon and effective ion–ion couplings while ignoring the first-order derivative terms expansion impacts of these two terms brought on by experiment defects.This paper proposes a novel robust quantum control optimization method in trapped ions.By introducing the first-order derivative terms caused by the error into the optimization cost function,we generate an extremely robust Mølmer–Sørensen gate with infidelity below 10^(−3) under a drift noise range of±10 kHz,the relative robustness achieves a tolerance of±5%,compared to the 200-kHz frequency spacing between phonon modes,and for time noise drift,the tolerance reached to 2%.Our work reveals the vital role of the first-order derivative terms of coupling in trapped ion pulse control optimization,especially the first-order derivative terms of ion–ion coupling.It provides a robust optimization scheme for realizing more efficient entangled states in trapped ion platforms.
基金supported by the Innovation Program for Quantum Science and Technology (Grant No.2021ZD0301603)the National Natural Science Foundation of China (Grant No.92165206)。
文摘Trapped-ion systems are one of the leading platforms for quantum information processing, where a key challenge is to scale up system size while maintaining high-fidelity two-qubit operations. A promising approach is to build high-performance modules interconnected via strong coupling. In particular, axial motional modes offer a practical mechanism to couple the ions in a chain, enabling the preparation of Greenberger–Horne–Zeilinger states with up to 24 ions using global operations, as well as high-fidelity two-qubit gates(96.6%–98.0%) in fully connected five-ion chains. Here, we demonstrate two-qubit quantum logic gates in a 5-ion^(40)Ca^(+)chain using axial modes, achieving fidelities exceeding 99% for adjacent pairs and over 98% for arbitrary pairs by carefully tackling dominant error sources. Our results are beneficial to the development of scalable ion-trap quantum processors,quantum simulation and quantum-enhanced metrology.
基金supported by the "Wenchuan Earthquake Fault Scientific Drilling" of the National Science Foundation of China
文摘This article is to review results from scientific drilling and fault-zone trapped waves （FZTWs） at the south Longman-Shan fault （LSF） zone that ruptured in the 2008 May 12 M8 Wenchuan earthquake in Sichuan,China.Immediately after the mainshock,two Wenchuan Fault Scientific Drilling （WFSD） boreholes were drilled at WFSD-1 and WFSD-2 sites approximately 400 m and 1 km west of the surface rupture along the Yinxiu-Beichuan fault （YBF）,the middle fault strand of the south LSF zone.Two boreholes met the principal slip of Wenchuan earthquake along the YBF at depths of 589-m and 1230-m,respectively.The slip is accompanied with a 100-200-m-wide zone consisting of fault gouge,breccia,cataclasite and fractures.Close to WFSD-1 site,the nearly-vertical slip of ～4.3-m with a 190-m wide zone of highly fractured rocks restricted to the hanging wall of the YBF was found at the ground surface after the Wenchuan earthquake.A dense linear seismic array was deployed across the surface rupture at this venue to record FZTWs generated by aftershocks.Observations and 3-D finite-difference simulations of FZTWs recorded at this cross-fault array and network stations close to the YBF show a distinct low-velocity zone composed by severely damaged rocks along the south LSF at seismogenic depths.The zone is several hundred meters wide along the principal slip,within which seismic velocities are reduced by ～30-55％ from wall-rock velocities and with the maximum velocity reduction in the ～200-m-wide rupture core zone at shallow depth.The FZTW-inferred geometry and physical properties of the south LSF rupture zone at shallow depth are in general consistent with the results from petrological and structural analyses of cores and well log at WFSD boreholes.We interpret this remarkable low-velocity zone as being a break-down zone during dynamic rupture in the 2008 M8 earthquake.We examined the FZTWS generated by similar earthquakes before and after the 2008 mainshock and observed that seismic velocities within fault core zone was reduced by ～10％ due to severe damage of fault rocks during the M8 mainshock.Scientific drilling and locations of aftershocks generating prominent FZTWs also indicate rupture bifurcation along the YBF and the Anxian-Guangxian fault （AGF）,two strands of the south LSF at shallow depth.A combination of seismic,petrologic and geologic study at the south LSF leads to further understand the relationship between the fault-zone structure and rupture dynamics,and the amplification of ground shaking strength along the low-velocity fault zone due to its waveguide effect.
基金sponsored by National Natural Science Foundation of China (No.40674043, 90814001)China Earthquake Admini-stration (Wenchuan Earthquake Scientific Survey 03-05)The contribution No. of this paper is RCEG 0905 of Geophysical Prospecting Center,China Earthquake Administration
文摘The rupture process of the May 12, 2008 Ms8.0 Wenchuan earthquake was very complex. To study the rupture zones generated by this earthquake, four dense temporary seismic arrays across the two surface breaking traces of the main-shock were deployed in July and recorded a great amount of aftershocks. This paper focuses on the data interpretation of two arrays across the central main fault, the northern array line 1 and southern array line 3. The fault zone trapped waves recorded by the two arrays were used to study the structure of the central main fault and the difference between the northern and southern portions. The results show that the widths of the rupture zone are about 170-200 m and 200-230 m for northern and southern portions respectively. And the corresponding dip angles are 80° and 70°. The seismic velocity inside the fracture zone is about one half of the host rock. By comparison, the northern portion of the rupture zone is slightly narrower and steeper than the southern portion. Besides these differences, one more interesting and important difference is the positions of the rupture zone with respect to surface breaking traces. At the northern portion, the rupture zone is centered at the surface breaking trace, while at the southern portion it is not but is shifted to the northwest. This difference reflects the difference of rupture behaviors between two portions of the central main fault. The width of the rupture zone is smaller than that of MS.1 Kunlun earthquake though these two earthquakes have almost the same magnitudes. Multiple ruptures may be one factor to cause the narrower rupture zone.
文摘Trapped vortex combustor （TVC） is an advanced low-pollution gas turbine combustor, with the adoption of staged combustion technique. To achieve low-pollutant emission and better combustion performance, the proportion of the air flow in each combustion zone should be precisely determined in the design of the combustor. Due to the presence of entrainment phenomenon, the total air flow in the cavity zone is difficult to estimate. To overcome the measurement difficulty, this study adopts the indirect measurement approach in the experimental research of entrainment phenomenon in the cavity. In accordance with the measurement principle, a TVC model fueled by methane is designed. Under two experimental conditions, i.e. with and without direct air intake in the cavity, the influence of the mainstream air flow velocity, the air intake velocity in the cavity, the height of inlet channel, the structure of holder and the structural proportion of the cavity on entrainment in the cavity is studied, respectively, through experiment at atmospheric temperature and pressure. The results suggest that the air flow velocity of mainstream, the air intake velocity of the cavity and the structure of the holder exert significant influence on the air entrainment, while the influence of structural proportion of the cavity is comparatively insignificant. The square root of momentum ratio of cavity air to mainstream air could be used to analyze the correlation of the entrainment data.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11764039,11847304,11865014,11475027,11274255 and 11305132the Natural Science Foundation of Gansu Province under Grant No 17JR5RA076the Scientific Research Project of Gansu Higher Education under Grant No 2016A-005
文摘The modulational instability of two-component Bose-Einstein condensates(BECs)under an external parabolic potential is discussed.Based on the trapped two-component Gross-Pitaevskill equations,a time-dependent dispersion relation is obtained analytically by means of the modified lens-type transformation and linear stability analysis.It is shown that a modulational unstable time scale exists for trapped two-component BECs.The modulational properties-which are determined by the wave number,external trapping parameter,intraand inter-species atomic interactions-are modified significantly.The analytical results are confirmed by direct numerical simulation.Our results provide a criterion for judging the occurrence of instability of the trapped two-component BECs in experiment.
基金Project supported by the National Natural Science Foundation of China （Grant No 10374025）.
文摘An effective teleportation scheme for an unknown ionic internal state via trapped ions is proposed without joint Bell-state measurement （BSM）. In the constructed quantum channel process, we make use of entanglement swapping to avoid decrease in entanglement during the distributing of particles. Thus our scheme provides new prospects for quantum teleportatlon in a longer distance. The distinct advant.age of our scheme is insensitive to the heating of vibrational mode. Furthermore, our scheme has no any individual optical access, and the successful probability also can reach 1.
基金partially supported by the National Natural Science Foundation of China(Grant Nos.11702244,51679014,51809209)the Joint Fund of Zhoushan City and Zhejiang University(Grant No.2017C82223)the Open Fund of Hunan Provincial Key Laboratory of Key Technology on Hydropower Development(Grant No.PKLHD201707)
文摘To evaluate the trapped wave energy and energy loss, the problem of wave scattering by twin fixed vertical surface- piercing plates over a stepped bottom is numerically simulated using the open source package OpenFOAM and the associated toolbox waves2Foam. The volume of fluid (VOF) method was employed to capture the free surface in the time domain. The validation of the present numerical model was performed by comparing with both the analytical and experimental results. The effects of the spacing between two plates and the configuration of stepped bottom on the hydrodynamic characteristics, such as reflection and transmission coefficients, viscous dissipation ratio, and relative wave height between the plates (termed as trapped wave energy), were examined. Moreover, the nonlinear effects of the incident wave height on the hydrodynamic characteristics were addressed as well. The results show that the step configuration can be tuned for efficient-performance of wave damping, and the optimum configurations of the step length B, the step height h1 and the spacing b, separately equaling λ/4, 3h/4, and 0.05h (λ and h are the wavelength and the water depth, respectively), are recommended for the trapping of wave energy.
基金Project supported by the Postdoctal Foundation of Central South University of Chinathe Important Program of Hunan Provincial Education Department of China (Grant No. 06A038)+1 种基金Department of Education of Hunan Province of China (Grant No. 06C080)Hunan Provincial Natural Science Foundation,China (Grant No. 07JJ3013)
文摘This paper proposes a simple scheme to generate a four-atom entangled cluster state in cavity quantum electrodynamics. With the assistantce of a strong classical field the cavity is only virtually excited and no quantum information will be transferred from the atoms to the cavity during the preparation for a four-atom entangled cluster state, and thus the scheme is insensitive to the cavity field states and cavity decay. Assuming that deviation of laser intensity is 0.01 and that of simultaneity for the interaction is 0.01, it shows that the fidelity of the resulting four-atom entangled cluster state is about 0.9886. The scheme can also be used to generate a four-ion entangled cluster state in a hot trapped-ion system. Assuming that deviation of laser intensity is 0.01, it shows that the fidelity of the resulting four-ion entangled cluster state is about 0.9990. Experimental feasibility for achieving this scheme is also discussed.
基金Project supported by the National Natural Science Foundation of China (Grant No. 60878059)the Science Foundation of the Educational Committee of Fujian Province of China (Grant No. JA09041)Fujian Normal University (Grant Nos. 2008100220and BKL2009-010)
文摘This paper considers a scheme for the preparation of two-qutrit entangled states via adiabatic passage in iontrapped system. In the proposal, the two three-level V-type ions are initially cooled to the ground states and need not be separately addressed. Moreover, only the ionic states act as memory and the system evolves in the dark space during the whole procedure, which makes the system robust against the decoherence and the fluctuation of the laser pulse.
文摘We propose a scheme to generate entangled coherent states for the vibrational modes of N trapped ions.In the scheme the first ion is sequentially excited by two travelling wave laser fields tuned to the ion transition. The scheme works in the strong-excitation regime, which is of experimental importance in view of decoherence.
基金Aeronautical Science Foundation of China (2008ZB52013)Funding of Jiangsu Innovation Program for Graduate Education (CXLX11_0211)
文摘A trapped vortex combustor （TVC） has been a very promising novel concept for it offers improvements in lean blow out, altitude relight, operating range, as well as a potential to decrease NOx emissions compared to conventional combustors. The present paper discusses the improved designs of the new combustor over the prior ones of our research group, including that：a） the over-all dimensions, both axial and radial, are reduced to those of an actual aero-engine combustor; b） the air flow distribution is optimized, and especially 15% of the air is fed into the liner as cooling air; c） a straight-wall diffuser with divergence angle 9°is added. A series of experiments （cavity-fueled only, under atmospheric pressure） has been conducted to investigate the performance of the improved TVC. Experimental results show that at the inlet temperature of 523 K, the inlet pressure of 0.1 MPa, stable operation of the TVC test rig is observed for the Mach number 0.15-0.34, indicating good flame stability; the combustion efficiency obtained in this paper falls into the range of 60%-96%; as the total excess air ratio increases, the combustion efficiency decreases, while the increase of the inlet temperature is beneficial to high combustion efficiency; besides, the optimal Mach numbers for high combustion efficiency under different inlet conditions are confirmed. The outlet temperature profiles feature a bottom in the midheight of the exit. This paper demonstrates the feasibility for the TVC to be applied to a realistic aero-engine preliminarily and provides reference for TVC design.
基金supported by the National Natural Science Foundation ofChina(41074069,40974053,90814001)RRCEG201103
文摘Trapped waves in the Qingchuan fault zone were observed at Muyu near the northeastern end of the fractured zone of the Wenchuan Ms8. 0 earthquake. The results indicate a fault-zone width of about 200 m and a great difference in physical property of the crust on different sides of the fault. The inferred location of crustal changes is consistent with land-form boundary on the surface
基金the National Natural Science Foundation of China(Nos.41266002,41406031,41406044)the Special Fund for Basic Scientific Research Business of Central Public Research Institutes(No.2015P02)the Fund of Key Laboratory of Global Change and Marine-Atmospheric Chemistry,SOA(No.GCMAC1308)for their support
文摘In this paper, we apply an unstructured grid coastal ocean model to simulate variations in the sea level and currents forced by two typhoons in the northwestern South China Sea(SCS). The model simulations show distinct differences for the two cases in which the typhoon paths were north and south of the Qiongzhou(QZ) Strait. In both cases, coastal trapped waves(CTWs) are stimulated but their propagation behaviors differ. Model sensitivity simulations suggest the dominant role played by alongshore wind in the eastern SCS(near Shanwei) and southeast of Hainan Island. We also examine the influence of the Leizhou Peninsula by changing the coastline in simulation experiments. Based on our results, we can draw the following conclusions: 1) The CTWs stimulated by the northern typhoon are stronger than the southern CTW. 2) In the two cases, the directions of the current structures of the QZ cross-transect are reversed. The strongest flow cores are both located in the middle-upper area of the strait and the results of our empirical orthogonal function analysis show that the vertical structure is highly barotropic. 3) The simulated CTWs divide into two branches in the QZ Strait for the northern typhoon, and an island trapped wave(ITW) around Hainan Island for the southern typhoon. 4) The Leizhou Peninsula plays a significant role in the distribution of the kinetic energy flux between the two CTW branches. In the presence of the Leizhou Peninsula, the QZ branch has only 39.7 percent of the total energy, whereas that ratio increases to 72.2 percent in its absence.
文摘In this article,we review our previous research for spatial and temporal characterizations of the San Andreas Fault(SAF)at Parkfield,using the fault-zone trapped wave(FZTW)since the middle 1980s.Parkfield,California has been taken as a scientific seismic experimental site in the USA since the 1970s,and the SAF is the target fault to investigate earthquake physics and forecasting.More than ten types of field experiments(including seismic,geophysical,geochemical,geodetic and so on)have been carried out at this experimental site since then.In the fall of 2003,a pair of scientific wells were drilled at the San Andreas Fault Observatory at Depth(SAFOD)site;the main-hole(MH)passed a~200-m-wide low-velocity zone(LVZ)with highly fractured rocks of the SAF at a depth of~3.2 km below the wellhead on the ground level(Hickman et al.,2005;Zoback,2007;Lockner et al.,2011).Borehole seismographs were installed in the SAFOD MH in 2004,which were located within the LVZ of the fault at~3-km depth to probe the internal structure and physical properties of the SAF.On September 282004,a M6 earthquake occurred~15 km southeast of the town of Parkfield.The data recorded in the field experiments before and after the 2004 M6 earthquake provided a unique opportunity to monitor the co-mainshock damage and post-seismic heal of the SAF associated with this strong earthquake.This retrospective review of the results from a sequence of our previous experiments at the Parkfield SAF,California,will be valuable for other researchers who are carrying out seismic experiments at the active faults to develop the community seismic wave velocity models,the fault models and the earthquake forecasting models in global seismogenic regions.
文摘A method of solving an ultracold trapped ion at the node of the standing wave laser without rotating wave approximation is proposed and the analytical forms of the eigenfunctions and eigenenergies of the system are presented.
基金Project supported by the National Natural Science Foundation of China （Grant No 10574022）, and the Funds of the Natural . Science of Fujian Province, China （Grant No Z0512006）.
文摘We propose a scheme for the preparation of one-dimensional and two-dimensional cluster states by using hot trapped ions. The scheme is based on the interaction between two ions and bichromatic radiation. The vibrational mode in our protocol is only virtually excited so that the system is insensitive to the thermal field. In addition, we only use two levels of ions as qubits and the successful probability may achieve 100%.
基金Project supported by the National Natural Science Foundation of China （Grant No 10374025）.
文摘Beyond the Lamb-Dicke limit, this paper investigates the squeezing properties of the trapped ion in the travelling- wave laser. It shows that the squeezing properties of the trapped ion in the travelling-wave laser are strongly affected by the sideband number k, the Lamb-Dicke parameter η and the initial average phonon number.
