The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing.Therefore,qudits have gained increased attention in recent research for their precise an...The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing.Therefore,qudits have gained increased attention in recent research for their precise and efficient operations.In this work,we demonstrate the complete population transfer between the next-adjacent energy levels of a transmon qudit using the Pythagorean coupling method and energy level mapping.We achieve a|0>to|2>transfer with a process fidelity of 97.76%in the subspace spanned by|0>to|2>.Moreover,the transfer operation is achieved within a remarkably fast timescale,as short as 20 ns.This study may present a promising avenue for enhancing the operation flexibility and efficiency of qudits in future implementations.展开更多
High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number.We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength,and demonstrate the CZ gat...High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number.We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength,and demonstrate the CZ gate using two different schemes,adiabatic and diabatic methods.The Clifford based randomized benchmarking(RB) method is used to assess and optimize the CZ gate fidelity.The fidelities of adiabatic and diabatic CZ gates are 99.53(8)% and 98.72(2)%,respectively.We also analyze the errors induced by the decoherence.Comparing to 30 ns duration time of adiabatic CZ gate,the duration time of diabatic CZ gate is 19 ns,revealing lower incoherence error rate r’_(incoherent),int=0.0197(5) compared to r_(incoherent,int)=0.0223(3).展开更多
A hybrid energy storage system(HESS)plays an important role in balancing the cost with the performance in terms of stabilizing the fluctuant power of wind farms and photovoltaic(PV)stations.To further bring down the c...A hybrid energy storage system(HESS)plays an important role in balancing the cost with the performance in terms of stabilizing the fluctuant power of wind farms and photovoltaic(PV)stations.To further bring down the cost and actually implement the dispatchability of wind/PV plants,there is a need to penetrate into the major factors that contribute to the cost of the any HESS.This paper first discusses hybrid energy storage systems,as well as chemical properties in different medium,deeming the ramp rate as one of the determinants that must be observed in the cost calculation.Then,a mathematical tool,Copula,is explained in details for the purpose of unscrambling the dependences between the power of wind and PV plants.To lower the cost,the basic rule for allocation of buffered power is also put forward,with the minimum energy capacities of the battery ESS(BESS)and the supercapacitor ESS(SC-ESS)simultaneously determined by integration.And the paper introduces the probability method to analyze how power and energy is compensated in certain confidence level.After that,two definitions of coefficients are set up,separately describing energy storage status and wind curtailment level.Finally,the paper gives a numerical example stemmed from real data acquired in wind farms and PV stations in Belgium.The conclusion presents that the cost of a hybrid energy storage system is greatly affected by ramp-rate and dependence between the power of wind farms and photovoltaic stations,in which dependence can easily be determined by Copulas.展开更多
The identification of spacial noise correlation is of critical importance in developing error-corrected quantum devices,but it has barely been studied so far.In this work,we utilize an effective method called qubit mo...The identification of spacial noise correlation is of critical importance in developing error-corrected quantum devices,but it has barely been studied so far.In this work,we utilize an effective method called qubit motion,to efficiently determine the noise correlations between any pair of qubits in a 7-qubit superconducting quantum system.The noise correlations between the same pairs of qubits are also investigated when the qubits are at distinct operating frequencies.What’s more,in this multi-qubit system with the presence of noise correlations,we demonstrate the enhancing effect of qubit motion on the coherence of logic qubits,and we propose a Motion-CPMG operation sequence to more efficiently protect the logic state from decoherence,which is experimentally demonstrated to extend the coherence time of logic qubits by nearly one order of magnitude.展开更多
Diffusion curves can be used to generate vector graphics images with smooth variation by solving Poisson equations. However, using the classical diffusion curve model, it is difficult to ensure that the generated diff...Diffusion curves can be used to generate vector graphics images with smooth variation by solving Poisson equations. However, using the classical diffusion curve model, it is difficult to ensure that the generated diffusion image satisfies desired constraints. In this paper, we develop a model for producing a diffusion image by solving a diffusion equation with diffusion coefficients, in which color layers and coefficient layers are introduced to facilitate the generation of the diffusion image. Doing so allows us to impose various constraints on the diffusion image, such as diffusion strength, diffusion direction,diffusion points, etc., in a unified computational framework. Various examples are presented in this paper to illustrate the capabilities of our model.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.11890704,12004042,12104055,and 12104056)Natural Science Foundation of Beijing (Grant No.Z190012)Key Area Research and Development Program of Guangdong Province (Grant No.2018B030326001)。
文摘The utilization of qudits in quantum systems has led to significant advantages in quantum computation and information processing.Therefore,qudits have gained increased attention in recent research for their precise and efficient operations.In this work,we demonstrate the complete population transfer between the next-adjacent energy levels of a transmon qudit using the Pythagorean coupling method and energy level mapping.We achieve a|0>to|2>transfer with a process fidelity of 97.76%in the subspace spanned by|0>to|2>.Moreover,the transfer operation is achieved within a remarkably fast timescale,as short as 20 ns.This study may present a promising avenue for enhancing the operation flexibility and efficiency of qudits in future implementations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11890704,12004042,and 11674376)the Natural Science Foundation of Beijing,China(Grant No.Z190012)+1 种基金the National Key Research and Development Program of China(Grant No.2016YFA0301800)the Key-Area Research and Development Program of Guang-Dong Province,China(Grant No.2018B030326001)。
文摘High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number.We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength,and demonstrate the CZ gate using two different schemes,adiabatic and diabatic methods.The Clifford based randomized benchmarking(RB) method is used to assess and optimize the CZ gate fidelity.The fidelities of adiabatic and diabatic CZ gates are 99.53(8)% and 98.72(2)%,respectively.We also analyze the errors induced by the decoherence.Comparing to 30 ns duration time of adiabatic CZ gate,the duration time of diabatic CZ gate is 19 ns,revealing lower incoherence error rate r’_(incoherent),int=0.0197(5) compared to r_(incoherent,int)=0.0223(3).
基金supported by Shanghai Science and Technology Committee(13231204002)National Key Technology R&D Program of China(2015BAA01B02).
文摘A hybrid energy storage system(HESS)plays an important role in balancing the cost with the performance in terms of stabilizing the fluctuant power of wind farms and photovoltaic(PV)stations.To further bring down the cost and actually implement the dispatchability of wind/PV plants,there is a need to penetrate into the major factors that contribute to the cost of the any HESS.This paper first discusses hybrid energy storage systems,as well as chemical properties in different medium,deeming the ramp rate as one of the determinants that must be observed in the cost calculation.Then,a mathematical tool,Copula,is explained in details for the purpose of unscrambling the dependences between the power of wind and PV plants.To lower the cost,the basic rule for allocation of buffered power is also put forward,with the minimum energy capacities of the battery ESS(BESS)and the supercapacitor ESS(SC-ESS)simultaneously determined by integration.And the paper introduces the probability method to analyze how power and energy is compensated in certain confidence level.After that,two definitions of coefficients are set up,separately describing energy storage status and wind curtailment level.Finally,the paper gives a numerical example stemmed from real data acquired in wind farms and PV stations in Belgium.The conclusion presents that the cost of a hybrid energy storage system is greatly affected by ramp-rate and dependence between the power of wind farms and photovoltaic stations,in which dependence can easily be determined by Copulas.
基金This work was supported by the NSFC of China(Grants nos.11890704,12004042,11674376,11905100)the NSF of Beijing(Grant no.Z190012)+1 种基金National Key Research and Development Pro-gram of China(Grants no.2016YFA0301800)the Key-Area Re-search and Development Program of GuangDong Province(Grants no.2018B030326001).
文摘The identification of spacial noise correlation is of critical importance in developing error-corrected quantum devices,but it has barely been studied so far.In this work,we utilize an effective method called qubit motion,to efficiently determine the noise correlations between any pair of qubits in a 7-qubit superconducting quantum system.The noise correlations between the same pairs of qubits are also investigated when the qubits are at distinct operating frequencies.What’s more,in this multi-qubit system with the presence of noise correlations,we demonstrate the enhancing effect of qubit motion on the coherence of logic qubits,and we propose a Motion-CPMG operation sequence to more efficiently protect the logic state from decoherence,which is experimentally demonstrated to extend the coherence time of logic qubits by nearly one order of magnitude.
基金supported by the National Natural Science Foundation of China (No. 61379072)the National Key R&D Program of China (No. 2016YFB1001501)the Fundamental Research Funds for the Central Universities (No. 2017XZZX009-03)
文摘Diffusion curves can be used to generate vector graphics images with smooth variation by solving Poisson equations. However, using the classical diffusion curve model, it is difficult to ensure that the generated diffusion image satisfies desired constraints. In this paper, we develop a model for producing a diffusion image by solving a diffusion equation with diffusion coefficients, in which color layers and coefficient layers are introduced to facilitate the generation of the diffusion image. Doing so allows us to impose various constraints on the diffusion image, such as diffusion strength, diffusion direction,diffusion points, etc., in a unified computational framework. Various examples are presented in this paper to illustrate the capabilities of our model.