两个耦合约瑟夫森结磁通量子比特能级的研究

研究了两个(?)_(1z)(?)_(2z)Ising型耦合量子比特的能级,这是一种典型的赝自旋约瑟夫森结比特模型。论述了两个磁通量子比特通过耦合可以构成量子力学四能级系统;研究了两量子比特间主要因子含能量差ε,隧穿幅度t和耦合因子j(包括耦合强度和耦合方向)对能级的影响。结果表明:对于由两个相同量子比特构成的系统,在Φ=(1/2)Φ处,不仅两抗铁磁态的能级受控于耦合因子,它们之间的跃迁频率也由耦合因子控制。

Study on energy levels of two coupled Josephson junction flux qubits

We investigate the energy levels of two qubits that are coupled via (σ)1z (×)(σ)2z Ising-type of coupling. We demonstrate that two flux qubits can be coupled to form a quantum mechanical four level system. We not only investigate how the energy bias ε and tunneling amplitude t affect the energy levels, but also especially analyze the effect of the coupling factor j (both coupling strength and coupling direction) between two qubits. The results indicate that, for a two identical qubits system, not only the energy level of two antiferromagnetic states but also the transition frequency between them at φ = (1/2)φ0 is controlled by the coupling factors.