Design and performance of multiloop and washer SQUIDs intended for sub-kelvin operation

Abstract

We have developed a set of dc SQUIDs intended for frequency-domain multiplexed readout of transition edge sensor (TES) arrays. The first design is based on the Ketchen-style washer, and has exhibited a 1.2 × 10 −7 0 Hz 1/2 flux noise both at 4.2 and 0.43 K. The second design is based on the multiloop structure and utilizes the spoke-terminating resistors which double as junction shunts in order to minimize the excess noise due to the resonance damping. The multiloop device has exhibited a 3.5 × 10 −7 0 Hz 1/2 flux noise level at 4.2 K. The mutual inductances are chosen such that a typical ac-biased TES-based x-ray calorimeter would need only a moderate amount of negative feedback in order to handle the dynamic range of the signal.

Physics of proximity Josephson sensor

“…Since the proximity effect modifications in τ and NEP are in opposite directions, the resolving power is almost the same as that given in Eq. (15), which neglects the proximity corrections. This is shown in Fig.…”

Ultrasensitive proximity Josephson sensor with kinetic inductance readout

“…3(b) at different T bath . Here we set L = 100 nH, M = 10 nH, ω = 1 MHz, δΦ n = 10 −7 Φ 0 / √ Hz [14], and I b = 0.8I c (ν). Notably, very high S/N ratios can be achieved with the PJS in the 100 GHz -100 THz frequency range.…”

Two-stage locally linearized SQUID readout for frequency domain multiplexed calorimeter arrays

“…The total number of SQUIDs in the lower array is limited to 12, by the desire to keep the power dissipation low and to keep the input inductance below 4 nH. Similar to our previous design [16] there are multiple input pad pairs which lead to the low inductance summing point. gradiometric SQUID loop where feedback coil couples to one half and input coil to the second half of the gradiometer, which corresponds to the case k 1 = 0.7, k 2 = 0.7 and k 3 = 0.…”