Revin Leonid S, Pankratov Andrey L, Gordeeva Anna V, Yablokov Anton A, Rakut Igor V, Zbrozhek Victor O, Kuzmin Leonid S
Institute for Physics of Microstructures of RAS, GSP-105, Nizhny Novgorod, 603950, Russia.
Center of Cryogenic Nanoelectronics, Nizhny Novgorod State Technical University, Nizhny Novgorod, Russia.
Beilstein J Nanotechnol. 2020 Jun 23;11:960-965. doi: 10.3762/bjnano.11.80. eCollection 2020.
An aluminium Josephson junction (JJ), with a critical current suppressed by a factor of three compared with the maximal value calculated from the gap, is experimentally investigated for application as a threshold detector for microwave photons. We present the preliminary results of measurements of the lifetime of the superconducting state and the probability of switching by a 9 GHz external signal. We found an anomalously large lifetime, not described by the Kramers' theory for the escape time over a barrier under the influence of fluctuations. We explain it by the phase diffusion regime, which is evident from the temperature dependence of the switching current histograms. Therefore, phase diffusion allows for a significant improvement of the noise immunity of a device, radically decreasing the dark count rate, but it will also decrease the single-photon sensitivity of the considered threshold detector. Quantization of the switching probability tilt as a function of the signal attenuation for various bias currents through the JJ is observed, which resembles the differentiation between and + 1 photon absorption.
对一个铝约瑟夫森结（JJ）进行了实验研究，其临界电流与根据能隙计算出的最大值相比被抑制了三倍，旨在将其用作微波光子的阈值探测器。我们展示了超导态寿命以及9 GHz外部信号触发开关概率测量的初步结果。我们发现了异常长的寿命，这无法用克拉默斯理论来描述在涨落影响下越过势垒的逃逸时间。我们用相位扩散机制来解释这一现象，这从开关电流直方图的温度依赖性中可以明显看出。因此，相位扩散能够显著提高器件的抗噪声能力，从根本上降低暗计数率，但同时也会降低所考虑的阈值探测器的单光子灵敏度。观察到了通过JJ的各种偏置电流下开关概率倾斜度随信号衰减的量化情况，这类似于吸收(n)个和(n + 1)个光子之间的差异。
