Flux-coherent series SQUID array magnetometers operating above 77 K with superior white flux noise than single-SQUIDs at 4.2 K

Magnetic field tunable vortex diode made of YBa2Cu3O7−δ Josephson junction asymmetrical arrays

“…The amount of flux coupled into the array due to B E is also difficult to estimate considering the well-known large flux focusing effects in bicrystal Josephson junctions. 41,42 For these reasons, here we restrict ourselves with only a qualitative comparison between the model and the experimental data and this indicates good agreement between them.…”

“…These observations suggest that when N parallelarrays are connected in series, the ratchet efficiency decreases rapidly with N. This effect can be easily understood if considering the spread of I c of the individual JJ-arrays connected. 41 Indeed, since the resulting voltage of N parallel 10 JJ-arrays connected in series is the sum of all individual voltages for all bias currents taking values in the range (minimum I c to maximum I c ), some 10 JJ-arrays will be in the voltage state showing some ratchet efficiency (positive or negative) and some will be in the zero-voltage state showing no ratchet efficiency. Consequently, the overall effect on the entire device's ratchet efficiency will be diluted when connecting N parallel 10 JJ-arrays in series relative to a single 10 JJ-array.…”

“…The dimensionless magnetic flux h ¼ HS 1=2 =U 0 is measured in units of magnetic flux quantum per smallest loop area of the array. In the simulations, we also considered the effect of two types of structural fluctuations related to the JJ-arrays: (i) critical current fluctuations from junction to junction D J , with the average hD J i ¼ 0, i.e., I cn of the nth junction can vary randomly from the designed value (due to inhomogeneities of the bicrystal line 41 ) resulting in fluctuations of j cn ¼ I cn = I c h i; (ii) fluctuations in the array loop areas D A , with the average hD A i ¼ 0, due to the 1 lm finite resolution of photolithography used in the fabrication process. Finally, thermal fluctuations have been considered too: temporal unbiased d-correlated Gaussian white noise n n with intensity D, i.e., n n h i ¼ 0; n n ð0Þn n ðtÞ ¼ dðtÞ, which can occur, for instance, due to thermal noise or temporal current fluctuations of the external circuit.…”

“…3). Such B-tunability can find application in electronic devices based on multiple JJs such as rapid single flux quantum (RSFQ), 40 SQUIDs, 41 or superconducting quantum interference filters (SQIFs) 42,43 when a tunable preferential direction of flux flow is required. In order to qualitatively understand why efficiency changes sign when B is varied, it is important to understand that usually, during the device's operation, there are many U 0 per array loop involved in the ratchet's dynamics.…”

How to study spoken language understanding: a survey of neuroscientific methods

“…New types of MEG sensor -for example, using higher temperature super-conducting sensor arrays (e.g. Chesca, John, & Mellor, 2015) that can be placed closer to the scalpwould similarly be helpful in improving the spatial resolution of electrophysiological methods. Looking at brain stimulation, ways to increase the neural specificity or to extend the reach of non-invasive brain stimulation methods (e.g.…”