Increase of Phase Retrapping Effects in the Switching Rate from the Finite Voltage State of the Underdamped Intrinsic Josephson Junctions

Comparative Study of First and Second Switches with Nearly Identical Switching Current in Bi2Sr2Ca0.85Y0.15Cu2Oy Intrinsic Josephson Junctions

“…12,13) Thus, many experimental results 7,[9][10][11][12][13][14][15] support that the MQT state is realized even in the 2nd SWs of IJJs, although the value of T cr (typically ∼ 10 K for the optimal doped Bi2212 IJJs) is much higher than the value predicted in the conventional theory. 16) As a qualitative explanation for this anomaly, we proposed that the ac Josephson current occurring after the 1st SW possibly passes through other junctions near the phase-switched junction, inducing the rapid oscillation in a tilted-washboard potential and effectively reducing the barrier height ∆U(I) for the 2nd SW. 11) Similar effects are expected for the quantum phase escapes under the strong microwave irradiation. Fistul et al reported that the strong microwaves effectively reduced ∆U(I) and increased the MQT rate, by using the quantummechanical analyses of the measured results for the Nb/AlO x /Nb Josephson junctions.…”

“…rate for the 1st to the 4th SWs suggested that the phase-running state in the resistive branches enhances the phase retrapping effects in the higher order SWs rather than the self-heating effects. 11) In addition, the microwave-induced resonant peak structure was observed in the switching current distribution below T 2nd cr , suggesting the occurrence of the quantum phase escapes and the formation of energy level quantization (ELQ) in a potential well. 12,13) Thus, many experimental results 7,[9][10][11][12][13][14][15] support that the MQT state is realized even in the 2nd SWs of IJJs, although the value of T cr (typically ∼ 10 K for the optimal doped Bi2212 IJJs) is much higher than the value predicted in the conventional theory.…”

“…11) In addition, the microwave-induced resonant peak structure was observed in the switching current distribution below T 2nd cr , suggesting the occurrence of the quantum phase escapes and the formation of energy level quantization (ELQ) in a potential well. 12,13) Thus, many experimental results 7,[9][10][11][12][13][14][15] support that the MQT state is realized even in the 2nd SWs of IJJs, although the value of T cr (typically ∼ 10 K for the optimal doped Bi2212 IJJs) is much higher than the value predicted in the conventional theory. 16) As a qualitative explanation for this anomaly, we proposed that the ac Josephson current occurring after the 1st SW possibly passes through other junctions near the phase-switched junction, inducing the rapid oscillation in a tilted-washboard potential and effectively reducing the barrier height ∆U(I) for the 2nd SW. 11) Similar effects are expected for the quantum phase escapes under the strong microwave irradiation.…”

“…[2][3][4][5] The most striking feature is that a crossover temperature, T cr , to the MQT state in the phase switch from the first to the second resistive branch (2nd SW) is largely enhanced compared to that from the zero voltage to the first resistive branch (1st SW) in the multi-branched current-voltage (I-V) characteristics of IJJs. [6][7][8][9][10][11][12][13][14][15] An early study 6) suggested that such an enhancement was due to the self-heating effects in the first resistive state, based on the consideration that a series array of uniform Josephson junctions should show the same value of T cr as long as the current flowing in each junction agrees with the externally-applied bias current.However, the anomalous increase of T 2nd cr was found to be independent of the device structure of IJJs with different heat-transfer environment 7) and the order of phase switches, 10) throwing doubt on the self-heating effects after the 1st SW.…”

“…7,12) The measured data of P(I) and the corresponding switching rate Γ(I) as a function of bias current were analyzed by a single-junction model including both the thermally activated (TA) phase escapes and the multiple phase retrapping (PR) processes, based on the so-called resistively and capacitively shunted junction (RCSJ) model. 11,13) Other details including experimental methods to distinguish between each junction are described in a supplementary material. 22) shows a negative curvature in logarithmic plots and is located at a higher current region than that for the 1st SW.…”