Single-flux-quantum(SFQ)circuits have great potential in building cryogenic quantum-classical interfaces for scaling up superconducting quantum processors.SFQ-based quantum gates have been designed and realized.Howeve...Single-flux-quantum(SFQ)circuits have great potential in building cryogenic quantum-classical interfaces for scaling up superconducting quantum processors.SFQ-based quantum gates have been designed and realized.However,current control schemes are difficult to tune the driving strength to qubits,which restricts the gate length and usually induces leakage to unwanted levels.In this study,we design the scheme and corresponding pulse generator circuit to continuously adjust the driving strength by coupling SFQ pulses with variable intervals.This scheme not only provides a way to adjust the SFQ-based gate length,but also proposes the possibility to tune the driving strength envelope.Simulations show that our scheme can suppress leakage to unwanted levels and reduce the error of SFQ-based Clifford gates by more than an order of magnitude.展开更多
The low temperature phase transformation in the Cu_2ZnSnS_4（CZTS） films was investigated by laser annealing and low temperature thermal annealing.The Raman measurements show that a-high-power laser annealing could c...The low temperature phase transformation in the Cu_2ZnSnS_4（CZTS） films was investigated by laser annealing and low temperature thermal annealing.The Raman measurements show that a-high-power laser annealing could cause a red shift of the Raman scattering peaks of the kesterite（KS） structure and promotes the formation of the partially disordered kesterite（PD-KS） structure in the CZTS films,and the low-temperature thermal annealing only shifts the Raman scattering peak of KS phase by several wavenumber to low frequency and the broads Raman peaks in the low frequency region.Moreover,the above two processes were reversible.The Raman analyses of the CZTS samples prepared under different process show that the PD-KS structure tends to be found at low temperatures and low sulfur vapor pressures.Our results reveal that the control of the phase structure in CZTS films is feasible by adjusting the preparation process of the films.展开更多
Josephson parametric amplifiers (JPAs) with nearly quantum-limited noise performance have become indispensable devices for the measurements of superconducting quantum information. We have developed an all-Nb lumped-el...Josephson parametric amplifiers (JPAs) with nearly quantum-limited noise performance have become indispensable devices for the measurements of superconducting quantum information. We have developed an all-Nb lumped-element flux-driven JPA operating in the three-wave mixing mode. Our Nb-based JPA comprises Nb/Al-AlOx/Nb Josephson junctions, a parallel-plate capacitor with SiO2 dielectric sandwiched between two Nb layers, a bottom coplanar waveguides layer, and a top Nb wiring layer. We experimentally demonstrate a 20 dB gain over a 190 MHz bandwidth, a mean 1 dB compression of -123 dBm, and near quantum-limited noise performance. This fabrication process can be further used to design impedance transformed parametric amplifiers for multiple-qubit readout.展开更多
基金Project supported in part by the National Natural Science Foundation of China (Grant No.92065116)the Key-Area Research and Development Program of Guangdong Province,China (Grant No.2020B0303030002)+1 种基金the Shanghai Technology Innovation Action Plan Integrated Circuit Technology Support Program (Grant No.22DZ1100200)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No.XDA18000000)。
文摘Single-flux-quantum(SFQ)circuits have great potential in building cryogenic quantum-classical interfaces for scaling up superconducting quantum processors.SFQ-based quantum gates have been designed and realized.However,current control schemes are difficult to tune the driving strength to qubits,which restricts the gate length and usually induces leakage to unwanted levels.In this study,we design the scheme and corresponding pulse generator circuit to continuously adjust the driving strength by coupling SFQ pulses with variable intervals.This scheme not only provides a way to adjust the SFQ-based gate length,but also proposes the possibility to tune the driving strength envelope.Simulations show that our scheme can suppress leakage to unwanted levels and reduce the error of SFQ-based Clifford gates by more than an order of magnitude.
基金Project supported by the Natural Science Foundation for Youth Fund of Hebei Province,China(Grant No.A2016201087)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20131301120003)the National Natural Science Foundation of China(Grant Nos.11504078and 61504054)
文摘The low temperature phase transformation in the Cu_2ZnSnS_4（CZTS） films was investigated by laser annealing and low temperature thermal annealing.The Raman measurements show that a-high-power laser annealing could cause a red shift of the Raman scattering peaks of the kesterite（KS） structure and promotes the formation of the partially disordered kesterite（PD-KS） structure in the CZTS films,and the low-temperature thermal annealing only shifts the Raman scattering peak of KS phase by several wavenumber to low frequency and the broads Raman peaks in the low frequency region.Moreover,the above two processes were reversible.The Raman analyses of the CZTS samples prepared under different process show that the PD-KS structure tends to be found at low temperatures and low sulfur vapor pressures.Our results reveal that the control of the phase structure in CZTS films is feasible by adjusting the preparation process of the films.
基金Project supported by the National Natural Science Foundation of China(Grant No.92065116)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA18000000)the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2020B0303030002).
文摘Josephson parametric amplifiers (JPAs) with nearly quantum-limited noise performance have become indispensable devices for the measurements of superconducting quantum information. We have developed an all-Nb lumped-element flux-driven JPA operating in the three-wave mixing mode. Our Nb-based JPA comprises Nb/Al-AlOx/Nb Josephson junctions, a parallel-plate capacitor with SiO2 dielectric sandwiched between two Nb layers, a bottom coplanar waveguides layer, and a top Nb wiring layer. We experimentally demonstrate a 20 dB gain over a 190 MHz bandwidth, a mean 1 dB compression of -123 dBm, and near quantum-limited noise performance. This fabrication process can be further used to design impedance transformed parametric amplifiers for multiple-qubit readout.
