Effect of mutual inductance coupling on superconducting flux qubit decoherence

Yinghua Ji, Xiong Zou, Binbin Feng

Bao‐Long Liang, Ji‐Suo Wang, Xiang‐Guo Meng +1 more

T. Hime, B. L. T. Plourde, P. A. Reichardt +3 more

江燕燕 Yanyan Jiang, 徐华兰 Hualan Xu, 嵇英华 Yinghua Ji

In the Born-Markov approximation and two-level approximation, and using the Bloch-Redfield equation, the decoherence property of superconducting quantum circuit with a flux qubit is investigated.The influence on decoherence of the mutual inductance coupling between the circuit components is complicated.The mutual inductance coupling between different loops will decrease the decoherence time.However, the mutual inductance coupling of the same loop, in a certain interval, will increase the decoherence time.Therefore, we can control the decoherence time by changing the mutual inductance parameters such as the strength and direction of coupling.

Yang De Fang

In two-level approximation, we investigate the influence of mutual inductive coupling in superconducting quantum circuits on the decoherence of flux qubits under sub-Ohmic thermal bath environment by utilizing Bloch-Redfield function. The investigation results show: (1) The memory effect existing in the solid-state environment is beneficial to prolong the decoherence time of the superconducting flux qubit, building sub-Ohmic thermal bath environments can improve the decoherence of the solid-state qubit. (2) When the quantum system and the thermal bath are in weak coupling, generally speaking, the mutual coupling effect between circuit elements will destroy the quantum coherence; but when the quantum system and the thermal bath are in strong coupling, it will help to enhance the decoherence time by controlling the mutual inductive coupling between the loop components.

Evgeni V. Il’ichev