A Spread-Spectrum SQUID Multiplexer

TL;DR

This paper introduces a novel spread-spectrum SQUID multiplexer for TES x-ray calorimeters, aiming to improve multiplexing factors in high-slew-rate scenarios, especially at lower photon rates.

Contribution

It proposes a new multiplexing scheme that addresses high-slew-rate limitations in microwave SQUID multiplexers for TES x-ray detectors.

Findings

Potential to enable higher multiplexing factors

Applicable to low photon arrival rate scenarios

Addresses high-slew-rate multiplexing challenges

Abstract

The Transition-Edge Sensors (TES) is a mature, high-resolution x-ray spectrometer technology that provides a much higher efficiency than dispersive spectrometers such as gratings and crystal spectrometers. As larger arrays are developed, time-division multiplexing schemes operating at MHz frequencies are being replaced by microwave SQUID multiplexers using frequency-division multiplexing at GHz frequencies. However, the multiplexing factor achievable with microwave SQUIDs is limited by the high slew rate on the leading edge of x-ray pulses. In this paper, we propose a new multiplexing scheme for high-slew-rate TES x-ray calorimeters: the spread-spectrum SQUID multiplexer, which has the potential to enable higher multiplexing factors, especially in applications with lower photon arrival rates.