TY - JOUR
T1 - Study of microwave-induced phase switches from the finite voltage state in Bi2Sr2CaCu2Oy intrinsic Josephson junctions
AU - Kitano, Haruhisa
AU - Yamaguchi, Ayami
AU - Takahashi, Yusaku
AU - Kakehi, Daiki
AU - Ayukawa, Shin Ya
N1 - Funding Information:
We thank I. Kakeya, H. Asai, S. Kawabata, Y. Ota, and T. Koyama for fruitful discussion and valuable comments. This work was partly supported by Grants-in-Aid for Scientific Research from JSPS and MEXT of Japan (Grant Nos. 21560020, 24560017) and MEXT-Supported Program for the Strategic Research Foundation at Private Universities (2013-2017).
Publisher Copyright:
© Published under licence by IOP Publishing Ltd.
PY - 2017/7/26
Y1 - 2017/7/26
N2 - We study the microwave-induced phase switches from the finite voltage state for the underdamped intrinsic Josephson junctions (IJJs) made of Bi2Sr2CaCu2Oy (Bi2212). We observe the resonant double-peak structure in the switching current distribution at low temperatures. This feature is successfully explained by a quantum mechanical model where the strong microwave field effectively suppresses the potential barrier for the phase escape from a potential well and the macroscopic quantum tunneling (MQT) is resonantly enhanced. The detailed analyses considering the effects of multiple phase retrapping processes after the phase escape strongly suggest that the intense microwave field suppresses the energy-level spacing in the potential well, by effectively decreasing the fluctuation-free critical current and the Josephson plasma frequency. This effect also reduces the number of photons required for the multiphoton transition between the ground and the first excited states, making it possible to observe the energy level quantization in the MQT state. The temperature dependence of the resonance peak emerging in the switching rate clearly demonstrates that the quantized energy state can be survived up to ∼10 K, which is much higher than a crossover temperature predicted by the conventional Caldeira-Leggett theory.
AB - We study the microwave-induced phase switches from the finite voltage state for the underdamped intrinsic Josephson junctions (IJJs) made of Bi2Sr2CaCu2Oy (Bi2212). We observe the resonant double-peak structure in the switching current distribution at low temperatures. This feature is successfully explained by a quantum mechanical model where the strong microwave field effectively suppresses the potential barrier for the phase escape from a potential well and the macroscopic quantum tunneling (MQT) is resonantly enhanced. The detailed analyses considering the effects of multiple phase retrapping processes after the phase escape strongly suggest that the intense microwave field suppresses the energy-level spacing in the potential well, by effectively decreasing the fluctuation-free critical current and the Josephson plasma frequency. This effect also reduces the number of photons required for the multiphoton transition between the ground and the first excited states, making it possible to observe the energy level quantization in the MQT state. The temperature dependence of the resonance peak emerging in the switching rate clearly demonstrates that the quantized energy state can be survived up to ∼10 K, which is much higher than a crossover temperature predicted by the conventional Caldeira-Leggett theory.
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U2 - 10.1088/1742-6596/871/1/012008
DO - 10.1088/1742-6596/871/1/012008
M3 - Conference article
AN - SCOPUS:85027978885
VL - 871
JO - Journal of Physics: Conference Series
JF - Journal of Physics: Conference Series
SN - 1742-6588
IS - 1
M1 - 012008
T2 - 29th International Symposium on Superconductivity, ISS 2016
Y2 - 13 December 2016 through 15 December 2016
ER -