We propose a theoretical scheme for realizing the general conditional phase shift gate of charge qubits situated in a high-Q superconducting transmission line resonator. The phase shifting angle can be tuned from 0 to...We propose a theoretical scheme for realizing the general conditional phase shift gate of charge qubits situated in a high-Q superconducting transmission line resonator. The phase shifting angle can be tuned from 0 to 27r by simply adjusting the qubit-resonator detuning and the interaction time. Based on this gate proposal, we give a detailed procedure to implement the three-qubit quantum Fourier transform with circuit quantum eleetrodynamics （QED）. A careful analysis of the decoherence sources shows that the algorithm can be achieved with a high fidelity using current circuit QED techniques.展开更多
We propose an efficient scheme to generate multiqubit Greenberger-ttorne--Zeilinger （GHZ） states by one- step quantum operation in a driven circuit quantum electrodyna.mics （QED） system. Our proposal is based on a...We propose an efficient scheme to generate multiqubit Greenberger-ttorne--Zeilinger （GHZ） states by one- step quantum operation in a driven circuit quantum electrodyna.mics （QED） system. Our proposal is based on a unitary evolution exp[-iλSx^2], with Sx being the collective spin operator in x direction and A a controllable parameter, induced by driving the resonator. The quantum operation avoids resonator-field decay and may achieve the GHZ states with ideal success probability. The feasibility with the experimentally-demonstrated circuit QED system is also discussed.展开更多
We study the entanglement dynamics between two strongly-AC-driven superconducting charge qubitscoupled collectively to a zero temperature,dissipative resonator and find an unusual feather that the competing ofcreation...We study the entanglement dynamics between two strongly-AC-driven superconducting charge qubitscoupled collectively to a zero temperature,dissipative resonator and find an unusual feather that the competing ofcreation and annihilation of entanglement can lead to entanglement increasing,sudden death and revival.We alsocalculate the dependence of the death time on the initial state of the system.展开更多
We theoretically study the transparency and amplification of a weak probe field applied to the cavity in hybrid systems formed by a driven superconducting circuit QED system and a mechanical resonator,or a driven opto...We theoretically study the transparency and amplification of a weak probe field applied to the cavity in hybrid systems formed by a driven superconducting circuit QED system and a mechanical resonator,or a driven optomechanical system and a superconducting qubit.We find that both the mechanical resonator and the superconducting qubit can result in the transparency to a weak probe field in such hybrid systems when a strong driving field is applied to the cavity.We also find that the weak probe field can be amplified in some parameter regimes.We further study the statistical properties of the output field via the degrees of second-order coherence.We find that the nonclassicality of the output field strongly depends on the system parameters.Our studies show that one can control single-photon transmission in the optomechanical system via a tunable artificial atom or in the circuit QED system via a mechanical resonator.展开更多
We propose an effective method to realize the quantum phase gate the system in which the transmon qubits are capacitively coupled to of one qubit simultaneously controlling N qubits. We use a superconducting transmiss...We propose an effective method to realize the quantum phase gate the system in which the transmon qubits are capacitively coupled to of one qubit simultaneously controlling N qubits. We use 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 deco herence time （microsecond-scale）, and it is more immune to the l/（charge noise and has longer dephasing time due to the fa vorable properties of the transmon qubits in the system.展开更多
We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, w...We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, we focus on the question about how to implement a two-qubit geometric phase gate using superconducting circuit quantum electrodynamics with both single- and two-photon interaction between the qubits and the cavity modes. We find that the multiphoton processes are not only controllable but also improve the gating speed. The comparison with other physical systems and experimental feasibility are discussed in detail.展开更多
基金Supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China under Grant No. 200524the Program for New Century Excellent Talents of China under Grant No. 06-0920
文摘We propose a theoretical scheme for realizing the general conditional phase shift gate of charge qubits situated in a high-Q superconducting transmission line resonator. The phase shifting angle can be tuned from 0 to 27r by simply adjusting the qubit-resonator detuning and the interaction time. Based on this gate proposal, we give a detailed procedure to implement the three-qubit quantum Fourier transform with circuit quantum eleetrodynamics （QED）. A careful analysis of the decoherence sources shows that the algorithm can be achieved with a high fidelity using current circuit QED techniques.
基金Supported by the National Natural Science Foundation of China under Grant Nos.10874142 and 90921010
文摘We propose an efficient scheme to generate multiqubit Greenberger-ttorne--Zeilinger （GHZ） states by one- step quantum operation in a driven circuit quantum electrodyna.mics （QED） system. Our proposal is based on a unitary evolution exp[-iλSx^2], with Sx being the collective spin operator in x direction and A a controllable parameter, induced by driving the resonator. The quantum operation avoids resonator-field decay and may achieve the GHZ states with ideal success probability. The feasibility with the experimentally-demonstrated circuit QED system is also discussed.
基金Supported by Hunan Provincial Natural Science Foundation of China under Grant No. 10J J6010the Key Project Foundation and the Youngth Foundation of Education Commission of Hunan Province of China under Grant Nos. 10A095, 09B079the Youth Foundation from Huaihua University of China under Grant No. HHUQ2009-09
文摘We study the entanglement dynamics between two strongly-AC-driven superconducting charge qubitscoupled collectively to a zero temperature,dissipative resonator and find an unusual feather that the competing ofcreation and annihilation of entanglement can lead to entanglement increasing,sudden death and revival.We alsocalculate the dependence of the death time on the initial state of the system.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10975080,61025022,61174084 and 61134008)
文摘We theoretically study the transparency and amplification of a weak probe field applied to the cavity in hybrid systems formed by a driven superconducting circuit QED system and a mechanical resonator,or a driven optomechanical system and a superconducting qubit.We find that both the mechanical resonator and the superconducting qubit can result in the transparency to a weak probe field in such hybrid systems when a strong driving field is applied to the cavity.We also find that the weak probe field can be amplified in some parameter regimes.We further study the statistical properties of the output field via the degrees of second-order coherence.We find that the nonclassicality of the output field strongly depends on the system parameters.Our studies show that one can control single-photon transmission in the optomechanical system via a tunable artificial atom or in the circuit QED system via a mechanical resonator.
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 the system in which the transmon qubits are capacitively coupled to of one qubit simultaneously controlling N qubits. We use 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 deco herence time （microsecond-scale）, and it is more immune to the l/（charge noise and has longer dephasing time due to the fa vorable properties of the transmon qubits in the system.
基金Supported by the National Science Foundation of China under Grant Nos.11074070,10774042,and 10774163the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institute of Hunan Province+1 种基金the Key Project of Science and Technology of Hunan Province under Grant No.2010FJ2005the NKBRSFC under Grant No.2010CB922904
文摘We study the influence of multi-photon processes on the geometric quantum computation in the systems of superconducting qubits based on the displacement-like and the general squeezed operator methods. As an example, we focus on the question about how to implement a two-qubit geometric phase gate using superconducting circuit quantum electrodynamics with both single- and two-photon interaction between the qubits and the cavity modes. We find that the multiphoton processes are not only controllable but also improve the gating speed. The comparison with other physical systems and experimental feasibility are discussed in detail.
