We propose a simple scheme to generate x-type four-charge entangled states by using SQUID-based charge qubits capacitively coupled to a transmission line resonator （TLR）. The coupling between the superconducting qub...We propose a simple scheme to generate x-type four-charge entangled states by using SQUID-based charge qubits capacitively coupled to a transmission line resonator （TLR）. The coupling between the superconducting qubit and the TLR can be effectively controlled by properly adjusting the control parameters of the charge qubit. The experimental feasibility of our scheme is also shown.展开更多
We propose an effective method to produce four-qubit x-type entangled states by using flux qubits coupled to an LC circuit which acts as a quantum data bus (QDB).In our scheme,the interaction is mediated by the exchan...We propose an effective method to produce four-qubit x-type entangled states by using flux qubits coupled to an LC circuit which acts as a quantum data bus (QDB).In our scheme,the interaction is mediated by the exchange of virtual rather than real photons because of the large detuning between flux qubits and QDB,and then QDB-induced loss can be effectively avoided.The experimental feasibility of the scheme is also presented.展开更多
This paper proposes a scheme to generate, in an ion-trap, a type of multipartite maximally entangled state which was first introduced by Chen et al. [Chen P X, Zhu S Y and Guo G C 2006 Phys. Rev. A 74 032324]. The max...This paper proposes a scheme to generate, in an ion-trap, a type of multipartite maximally entangled state which was first introduced by Chen et al. [Chen P X, Zhu S Y and Guo G C 2006 Phys. Rev. A 74 032324]. The maximum entanglement property of these states is examined. It also demonstrates how to discriminate among these states in the ion-trap.展开更多
We examine the ability of quantum discord (QD) and entanglements (concurrence, EoF and negativity) to detect the critical points associated to quantum phase transitions (QPTs) for XY models, i.e., the isotropic XY mod...We examine the ability of quantum discord (QD) and entanglements (concurrence, EoF and negativity) to detect the critical points associated to quantum phase transitions (QPTs) for XY models, i.e., the isotropic XY model with three-spin interactions at zero temperature, and the anisotropic XY model in a transverse magnetic field h at finite temperatures. For the case of zero temperature, we found that both entanglements and QD can spotlight the critical points of QPTs for these two models. Moreover, QD versus distance M exhibits the long-range behavior of quantum correlation for the anisotropic XY model, while entanglement is short-ranged. For the case of finite temperatures, we found that negativity has the same behaviors with concurrence at or near transition points. Moreover, QD for the anisotropic XY model can increase with temperature even in the absence of a magnetic field.展开更多
We propose a one-step method to prepare multi-qubit GHZ and W states with transmon qubits capacitively coupled to a superconducting transmission line resonator(TLR).Compared with the scheme firstly introduced by Wang ...We propose a one-step method to prepare multi-qubit GHZ and W states with transmon qubits capacitively coupled to a superconducting transmission line resonator(TLR).Compared with the scheme firstly introduced by Wang et al.[Phys.Rev.B 81(2010) 104524],our schemes have longer dephasing time and much shorter operation time because the transmon qubits we used are not only more robust to the decoherence and the unavoidable parameter variations,but also have much stronger coupling constant with TLR.Based on the favourable properties of transmons and TLR,our method is more feasible in experiment.展开更多
基金supported by the National Natural Science Foundations of China (Grant Nos. 10947017/A05 and 11074190)the Science Foundation of the Key Laboratory of Novel Thin Film Solar Cells, China (Grant No. KF200912)the Graduates' Innovative Scientific Research Project of Zhejiang Province, China (Grant No. 2011831)
文摘We propose a simple scheme to generate x-type four-charge entangled states by using SQUID-based charge qubits capacitively coupled to a transmission line resonator （TLR）. The coupling between the superconducting qubit and the TLR can be effectively controlled by properly adjusting the control parameters of the charge qubit. The experimental feasibility of our scheme is also shown.
基金Supported by the National Natural Science Foundation of China under Grant No 10947017/A05Key Lab of Novel Thin Film Solar Cells(KF200912)+1 种基金Graduates’Innovative Scientific Research Project of Zhejiang Province(2011831)Graduate Innovation Foundation of Wenzhou University(3160601010952).
文摘We propose an effective method to produce four-qubit x-type entangled states by using flux qubits coupled to an LC circuit which acts as a quantum data bus (QDB).In our scheme,the interaction is mediated by the exchange of virtual rather than real photons because of the large detuning between flux qubits and QDB,and then QDB-induced loss can be effectively avoided.The experimental feasibility of the scheme is also presented.
基金Project supported by the Special Funds of the National Natural Science Foundation of China (Grant No. 10947017/A05)
文摘This paper proposes a scheme to generate, in an ion-trap, a type of multipartite maximally entangled state which was first introduced by Chen et al. [Chen P X, Zhu S Y and Guo G C 2006 Phys. Rev. A 74 032324]. The maximum entanglement property of these states is examined. It also demonstrates how to discriminate among these states in the ion-trap.
文摘We examine the ability of quantum discord (QD) and entanglements (concurrence, EoF and negativity) to detect the critical points associated to quantum phase transitions (QPTs) for XY models, i.e., the isotropic XY model with three-spin interactions at zero temperature, and the anisotropic XY model in a transverse magnetic field h at finite temperatures. For the case of zero temperature, we found that both entanglements and QD can spotlight the critical points of QPTs for these two models. Moreover, QD versus distance M exhibits the long-range behavior of quantum correlation for the anisotropic XY model, while entanglement is short-ranged. For the case of finite temperatures, we found that negativity has the same behaviors with concurrence at or near transition points. Moreover, QD for the anisotropic XY model can increase with temperature even in the absence of a magnetic field.
基金Supported by the National Natural Science Foundation of China under Grant No. 10947017/A05Key Lab of Novel Thin Film Solar Cells (KF200912)Graduates’ Innovative Scientific Research Project of Zhejiang Province under Grant No. 2011831
文摘We propose a one-step method to prepare multi-qubit GHZ and W states with transmon qubits capacitively coupled to a superconducting transmission line resonator(TLR).Compared with the scheme firstly introduced by Wang et al.[Phys.Rev.B 81(2010) 104524],our schemes have longer dephasing time and much shorter operation time because the transmon qubits we used are not only more robust to the decoherence and the unavoidable parameter variations,but also have much stronger coupling constant with TLR.Based on the favourable properties of transmons and TLR,our method is more feasible in experiment.
