Superconducting quantum detectors

Abstract:

Superconducting On-chip Fourier Transform Spectrometers (SOFTS) are broadband, ultra-compact and electronic interferometers. SOFTS will enable kilo-pixel spectro-imaging focal planes, enhancing sub-millimeter astrophysics and cosmology. Particular applications include cluster astrophysics, cosmic microwave background (CMB) science, and line intensity mapping. This article details the development, design and bench-marking of radio frequency (RF) on-chip architecture of SOFTS for Ka and W-bands.

Abstract:

Travelling wave parametric amplifiers (TWPAs) made from highly non-linear reactive superconducting thin films have been demonstrated to be a potentially viable quantum-noise-limited amplifier technology for various fundamental physics platforms, including microwave/mm/sub-mm astronomy, dark matter search experiments, neutrino mass experiments, and qubit readout. We present a kinetic inductance TWPA consisting of a patterned titanium nitride film on a sapphire substrate, which comprises a coplanar waveguide (CPW) with a continuous, smoothed periodic loading (PL) structure that modulates the characteristic impedance of the CPW in a double sinusoidal fashion. This double sinusoidal modulation creates much stronger dispersion features than a conventional PL design, which allows for phase matching and pump harmonic suppression over a much shorter transmission length, potentially leading to reduced losses. In this paper, we shall discuss in detail the design of our TWPA and present the predicted gain-bandwidth characteristics from electromagnetic simulations.

Abstract:

We report the design of a 230 GHz dual-polarization (2-pol) balanced Superconductor-Insulator-Superconductor (SIS) receiver that can be easily extended for large array applications. We achieve this by integrating all of the required radio frequency (RF) and local oscillator (LO) components on-chip using planar superconducting circuit technology, therefore simplifying the architecture of the receiver block substantially. One major feature of our design is the planar LO injection scheme, which couples the LO with a single on-chip antenna and distributes the LO power via a series of microstrip couplers to the balanced mixers of each polarization of each pixel. In this paper, we describe in detail the design and layout of the individual planar circuit components of our receiver, as well as how they are integrated to form a full receiver. We then conclude the paper with the design of a 2-pixel array demonstrator, illustrating how the balanced SIS mixer and the LO distribution network can be extended to form an even larger array.