We report the implementation of qubit-lubit coupling in a three-dimensional （3D） cavity, using the exchange of virtual photons, to realize logical operations. We measure single photon and multi-photon transitions in...We report the implementation of qubit-lubit coupling in a three-dimensional （3D） cavity, using the exchange of virtual photons, to realize logical operations. We measure single photon and multi-photon transitions in this qubit-qubit coupling system and obtain its energy avoided-crossing spectrum. With ac-Stark effect, fast control of the qubits is achieved to tune the effective coupling on and off and the state-swap gate SWAP is successfully constructed. Moreover, using two-photon transition between the ground state and doubly observed. A quarter period of this oscillation corresponds to states, bSWAP and are the foundations of future gate excited states, a kind of two-photon Rabi-like oscillation is the logical gate bSbSWAP, which is used for generating Bell preparation of two-qubit Bell states and realization of CNOT展开更多
Superconducting transmon qubits are the leading platform in solid-state quantum computing and quantum simulation applications.In this work,we develop a fabrication process for the transmon multiqubit device with a nio...Superconducting transmon qubits are the leading platform in solid-state quantum computing and quantum simulation applications.In this work,we develop a fabrication process for the transmon multiqubit device with a niobium base layer,shadow-evaporated Josephson junctions,and airbridges across the qubit control lines to suppress crosstalk.Our results show that these multiqubit devices have well-characterized readout resonators,and that the energy relaxation and Ramsey(spin-echo)dephasing times are up to∼40µs and 14(47)µs,respectively.We perform single-qubit gate operations that demonstrate a maximum gate fidelity of 99.97%.In addition,two-qubit vacuum Rabi oscillations are measured to evaluate the coupling strength between qubits,and the crosstalk among qubits is found to be less than 1%with the fabricated airbridges.Further improvements in qubit coherence performance using this fabrication process are also discussed.展开更多
We have realized a frequency-tunable transmon in a three-dimensional cooper cavity using a direct current supercon- ducting quantum interference device. Both the transition frequency of the transmon and the frequency ...We have realized a frequency-tunable transmon in a three-dimensional cooper cavity using a direct current supercon- ducting quantum interference device. Both the transition frequency of the transmon and the frequency of the dressed cavity can be varied with the applied external flux bias, which are well consistent with the theoretical model. The range of the variable transition frequency is from 5.188 GHz to 7.756 GHz. The energy relaxation time of the transmon is hundreds of nanoseconds.展开更多
We propose an effective method to realize the quantum phase gate of one qubit simultaneously controlling N qubits. We use the system in which the transmon qubits are capacitively coupled to a superconducting transmiss...We propose an effective method to realize the quantum phase gate of one qubit simultaneously controlling N qubits. We use the system in which the transmon qubits are capacitively coupled to a superconducting transmission line resonator driven by a strong microwave field. In our scheme, the phase gate can be realized in a time (nanosecond-scale) much shorter than decoherence time (microsecond-scale), and it is more immune to the 1/f charge noise and has longer dephasing time due to the favorable properties of the transmon qubits in the system.展开更多
基金Project supported by the National Basic Research and Development Program of China(Grant No.2011CBA00304)the National Natural Science Foundation of China(Grant Nos.60836001 and 61174084)the Tsinghua University Initiative Scientific Research Program,China(Grant No.20131089314)
文摘We report the implementation of qubit-lubit coupling in a three-dimensional （3D） cavity, using the exchange of virtual photons, to realize logical operations. We measure single photon and multi-photon transitions in this qubit-qubit coupling system and obtain its energy avoided-crossing spectrum. With ac-Stark effect, fast control of the qubits is achieved to tune the effective coupling on and off and the state-swap gate SWAP is successfully constructed. Moreover, using two-photon transition between the ground state and doubly observed. A quarter period of this oscillation corresponds to states, bSWAP and are the foundations of future gate excited states, a kind of two-photon Rabi-like oscillation is the logical gate bSbSWAP, which is used for generating Bell preparation of two-qubit Bell states and realization of CNOT
基金supported by the National Key R&D Program of China(Grant No.2016YFA0300601)the National Natural Science Foundation of China(Grant Nos.11934018 and 11874063)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB28000000)the Key-Area Research and Development Program of GuangDong Province,China(Grant No.2018B030326001)。
文摘Superconducting transmon qubits are the leading platform in solid-state quantum computing and quantum simulation applications.In this work,we develop a fabrication process for the transmon multiqubit device with a niobium base layer,shadow-evaporated Josephson junctions,and airbridges across the qubit control lines to suppress crosstalk.Our results show that these multiqubit devices have well-characterized readout resonators,and that the energy relaxation and Ramsey(spin-echo)dephasing times are up to∼40µs and 14(47)µs,respectively.We perform single-qubit gate operations that demonstrate a maximum gate fidelity of 99.97%.In addition,two-qubit vacuum Rabi oscillations are measured to evaluate the coupling strength between qubits,and the crosstalk among qubits is found to be less than 1%with the fabricated airbridges.Further improvements in qubit coherence performance using this fabrication process are also discussed.
基金supported by the National Basic Research Program of China(Grant Nos.2011CB922104 and 2011CBA00200)the National Natural Science Foundation of China(Grant No.11474154)+3 种基金the Natural Science Foundation of Jiangsu Province,China(Grant No.BK2012013)the Priority Academic Program Development of Jiangsu Higher Education Institutions,Chinathe Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120091110030)the Dengfeng Project B of Nanjing University,China
文摘We have realized a frequency-tunable transmon in a three-dimensional cooper cavity using a direct current supercon- ducting quantum interference device. Both the transition frequency of the transmon and the frequency of the dressed cavity can be varied with the applied external flux bias, which are well consistent with the theoretical model. The range of the variable transition frequency is from 5.188 GHz to 7.756 GHz. The energy relaxation time of the transmon is hundreds of nanoseconds.
基金supported by the National Natural Science Foundation of China (Grant No. 10947017/A05)the Key Lab of Novel Thin Film Solar Cells (Grant No. KF200912)Graduates’ Innovative Scientific Research Project of Zhejiang Province (Grant No. 2011831)
文摘We propose an effective method to realize the quantum phase gate of one qubit simultaneously controlling N qubits. We use the system in which the transmon qubits are capacitively coupled to a superconducting transmission line resonator driven by a strong microwave field. In our scheme, the phase gate can be realized in a time (nanosecond-scale) much shorter than decoherence time (microsecond-scale), and it is more immune to the 1/f charge noise and has longer dephasing time due to the favorable properties of the transmon qubits in the system.
