Recently, the superlattice (quantum well) material as a new kind of photoelectrode has drawn much attention in the field of photoelectrochemistry.Due to the energy quantization,the superlattices (quantum well) have a ...Recently, the superlattice (quantum well) material as a new kind of photoelectrode has drawn much attention in the field of photoelectrochemistry.Due to the energy quantization,the superlattices (quantum well) have a number of new展开更多
To meet the specification of the qubits in our laboratory,a 0.4 kA·cm^-2 superconducting rapid single flux quantum(RSFQ) circuit was designed and successfully fabricated with an improved Nb-based self-aligned lif...To meet the specification of the qubits in our laboratory,a 0.4 kA·cm^-2 superconducting rapid single flux quantum(RSFQ) circuit was designed and successfully fabricated with an improved Nb-based self-aligned lift-off process.This circuit consists of a single-fluxquantum(SFQ) pulse generator,a Josephson transmission line(JTL) and a T-flip flop(TFF),and it acts as a frequency divider.The values of the inductors in this circuit were extracted using InductEX and the basic function of this circuit was confirmed using the simulation software WRspice before fabrication.After fabrication,the basic parameters of this circuit were measured at ~2.5 K in a Janis He-3 cryostat.This work laid the theoretical and experimental basis for the future research on the RSFQqubit control circuits.展开更多
The principles and characteristics of rapid single flux quantum (RSFQ) circ- uits are discussed. According to these theories, we have designed RSFQ inverter, XOR cell and shift registers relative to the pseudo random ...The principles and characteristics of rapid single flux quantum (RSFQ) circ- uits are discussed. According to these theories, we have designed RSFQ inverter, XOR cell and shift registers relative to the pseudo random generator. Based on these cells, the RSFQ pseudo random generator is given. Compared with the simulation result of another mathematical model that is established by MATLAB, the design of the RSFQ pseudo random generator is proved to be reasonable and meets our expectations.展开更多
A rigorous theoretical model for Ino.53Gao.47As/InP single photon avalanche diode is utilized to investigate the dependences of single photon quantum efficiency and dark count probability on structure and operation co...A rigorous theoretical model for Ino.53Gao.47As/InP single photon avalanche diode is utilized to investigate the dependences of single photon quantum efficiency and dark count probability on structure and operation condition. In the model, low field impact ionizations in charge and absorption layers are allowed, while avalanche breakdown can occur only in the multiplication layer. The origin of dark counts is discussed and the results indicate that the dominant mechanism that gives rise to dark counts depends on both device structure and operating condition. When the multiplication layer is thicker than a critical thickness or the temperature is higher than a critical value, generation-recombination in the absorption layer is the dominative mechanism; otherwise band-to-band tunneling in the multiplication layer dominates the dark counts. The thicknesses of charge and multiplication layers greatly affect the dark count and the peak single photon quantum efficiency and increasing the multiplication layer width may reduce the dark count probability and increase the peak single photon quantum efficiency. However, when the multiplication layer width exceeds 1 μm, the peak single photon quantum efficiency increases slowly and it is finally saturated at the quantum efficiency of the single photon avalanche diodes.展开更多
Based on the previous work about the knotted pictures of quantum states, quantum logic gates and unitary transformations, this paper further gives the whole complete quantum measurement process of quantum teleportatio...Based on the previous work about the knotted pictures of quantum states, quantum logic gates and unitary transformations, this paper further gives the whole complete quantum measurement process of quantum teleportation from the viewpoint of knot theory.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Recently, the superlattice (quantum well) material as a new kind of photoelectrode has drawn much attention in the field of photoelectrochemistry.Due to the energy quantization,the superlattices (quantum well) have a number of new
基金financially supported by the Natural Science Foundation of China (No.60836001)the State Key Program for Basic Research of China (No.2011CBA00304)the Tsinghua University Initiative Scientific Research Program (No. 20131089314)
文摘To meet the specification of the qubits in our laboratory,a 0.4 kA·cm^-2 superconducting rapid single flux quantum(RSFQ) circuit was designed and successfully fabricated with an improved Nb-based self-aligned lift-off process.This circuit consists of a single-fluxquantum(SFQ) pulse generator,a Josephson transmission line(JTL) and a T-flip flop(TFF),and it acts as a frequency divider.The values of the inductors in this circuit were extracted using InductEX and the basic function of this circuit was confirmed using the simulation software WRspice before fabrication.After fabrication,the basic parameters of this circuit were measured at ~2.5 K in a Janis He-3 cryostat.This work laid the theoretical and experimental basis for the future research on the RSFQqubit control circuits.
基金The National Center for Research and Development on Superconductivity of China and the National Science Fund for Distinguished Young Scholars (B) (Grant No. 69801004).
文摘The principles and characteristics of rapid single flux quantum (RSFQ) circ- uits are discussed. According to these theories, we have designed RSFQ inverter, XOR cell and shift registers relative to the pseudo random generator. Based on these cells, the RSFQ pseudo random generator is given. Compared with the simulation result of another mathematical model that is established by MATLAB, the design of the RSFQ pseudo random generator is proved to be reasonable and meets our expectations.
基金supported by the National Basic Research Program of China (Grant Nos. G2001039302 and 007CB307001)the Guangdong Provincial Key Technology Research and Development Program,China (Grant No. 2007B010400009)
文摘A rigorous theoretical model for Ino.53Gao.47As/InP single photon avalanche diode is utilized to investigate the dependences of single photon quantum efficiency and dark count probability on structure and operation condition. In the model, low field impact ionizations in charge and absorption layers are allowed, while avalanche breakdown can occur only in the multiplication layer. The origin of dark counts is discussed and the results indicate that the dominant mechanism that gives rise to dark counts depends on both device structure and operating condition. When the multiplication layer is thicker than a critical thickness or the temperature is higher than a critical value, generation-recombination in the absorption layer is the dominative mechanism; otherwise band-to-band tunneling in the multiplication layer dominates the dark counts. The thicknesses of charge and multiplication layers greatly affect the dark count and the peak single photon quantum efficiency and increasing the multiplication layer width may reduce the dark count probability and increase the peak single photon quantum efficiency. However, when the multiplication layer width exceeds 1 μm, the peak single photon quantum efficiency increases slowly and it is finally saturated at the quantum efficiency of the single photon avalanche diodes.
文摘Based on the previous work about the knotted pictures of quantum states, quantum logic gates and unitary transformations, this paper further gives the whole complete quantum measurement process of quantum teleportation from the viewpoint of knot theory.
