United States National Committee of URSI National Radio Science Meeting
Superconducting parametric amplifiers: The next big thing in (Sub)millimeter-wave receivers
Omid Noroozian, Anthony R. Kerr, Jeffrey G. Mangum, Peter K. Day, Henry George LeDuc, Jonas Stasys Zmuidzinas, D. P. Woody, Arthur W. Lichtenberger, Michael E. Cyberey, Robert M. Weikle
We are developing a new superconducting amplifier technology for radio astronomy instruments called the Traveling-Wave Kinetic Inductance Parametric (TKIP) amplifier. Invented at Caltech/JPL, recent laboratory demonstrations have resulted in near quantum-limited noise performance over more than an octave of microwave bandwidth and operating temperatures as high as 3 Kelvin. These amplifiers have the potential to be used as front-end replacements for ALMA's mm/sub-mm SIS receivers and intermediate frequency (IF) amplifiers, and for multiplexing faint signals from focal-plane arrays of single-photon detectors on space telescopes such as NASA's Origins Space Telescope (OST). The enhanced observational capabilities that would be enabled by TKIP front-end amplifiers on ALMA would tremendously benefit ALMA science across all bands.
We are developing a new superconducting amplifier technology for radio astronomy instruments called the Traveling-Wave Kinetic Inductance Parametric (TKIP) amplifier. Invented at Caltech/JPL, recent laboratory demonstrations have resulted in near quantum-limited noise performance over more than an octave of microwave bandwidth and operating temperatures as high as 3 Kelvin. These amplifiers have the potential to be used as front-end replacements for ALMA's mm/sub-mm SIS receivers and intermediate frequency (IF) amplifiers, and for multiplexing faint signals from focal-plane arrays of single-photon detectors on space telescopes such as NASA's Origins Space Telescope (OST). The enhanced observational capabilities that would be enabled by TKIP front-end amplifiers on ALMA would tremendously benefit ALMA science across all bands.
The traveling-wave kinetic inductance parametric (TKIP) amplifier is a new amplifier technology capable of near quantum-limited sensitivity over a wide instantaneous bandwidth. Microwave frequency versions of these amplifiers, which are based on four-wave mixing in an NbTiN coplanar waveguide transmission line, have demonstrated high gain and noise corresponding to a few photons at several GHz. Their simple design is easily scalable to higher frequency, allowing for operation up to near the (> 1 THz) gap frequency of NbTiN. We will discuss the current state of the art of the TKIP operating at microwave frequencies and the potential use of these amplifiers as front ends for receivers in the millimeter and submillimeter bands. As an example, we describe the design of a TKIP tuned for the W-band.
Traveling-wave parametric amplifiers based on superconducting NbTiN films are being developed that provide gain over nearly an octave of bandwidth at microwave frequencies. The amplifiers are non-linear transmission lines, where the nonlinearity comes from the current dependence of the kinetic inductance. Amplification results from three and four-wave mixing processes, and phase matching over a wide frequency range is achieved by engineering the dispersion characteristics of the transmission line. Recent noise measurements over a wide frequency band demonstrate that the added noise of these amplifiers is close to one half photon, consistent with the quantum limit for a phase preserving amplifier. We will discuss applications of this class of amplifier to astronomical instruments.
Ultralow-noise microwave amplification and detection play a central role in different applications, going from fundamental physics experiments to the deployment of quantum technologies. In many applications the necessity of reading multiple detectors, or cavities or qubits, calls for large bandwidth amplifiers with the lowest possible noise. Current technologies are based on High Electron Mobility Transistors and Josephson Parametric Amplifiers. Both have limitations, the former in terms of the minimum noise, the latter in terms of bandwidth. Superconducting Traveling Wave Parametric Amplifiers (TWPAs) have the potential of offering quantum limited noise and large bandwidth. These amplifiers are based on the parametric amplification of microwaves traveling along a transmission line with embedded nonlinear elements. We are developing superconducting TWPAs based both on Josephson junction arrays (Traveling Wave Josephson Parametric Amplifiers) and on nonlinear kinetic inductance (Dispersion Engineered Traveling Wave Kinetic Inductance Amplifiers). Our goal is to achieve large bandwidth (in the 5 to 10 GHz range), large gain (more than 20 dB), large saturation power (more than −50 dBm), and near quantum limited noise (noise temperature less than 600 mK). Current achievements in the design and development of the high performance TWPAs are here reported and discussed, together with current limitations and possible future developments.
The W-Band (75−110GHz) sky contains a plethora of information about star formation, galaxy evolution and the cosmic microwave background. We have designed and fabricated a dual-purpose superconducting circuit to facilitate the next generation of astronomical observations in this regime by providing proof-of-concept for both a millimeter-wave low-loss phase shifter, which can operate as an on-chip Fourier transform spectrometer (FTS) and a traveling wave kinetic inductance parametric amplifier (TKIP). Superconducting transmission lines have a propagation speed that depends on the inductance in the line which is a combination of geometric inductance and kinetic inductance in the superconductor. The kinetic inductance has a non-linear component with a characteristic current, I∗, and can be modulated by applying a DC current, changing the propagation speed and effective path length. Our test circuit is designed to measure the path length difference or phase shift, Δϕ, between two symmetric transmission lines when one line is biased with a DC current. To provide a measurement of Δϕ, a key parameter for optimizing a high gain W-Band TKIP, and modulate signal path length in FTS operation, our 3.6×2.5cm chip employs a pair of 503mm long NbTiN inverted microstrip lines coupled to circular waveguide ports through radial probes. For a line of width 3μm and film thickness 20nm, we predict Δϕ≈1767rad at 90GHz when biased at close to I∗. We have fabricated a prototype with 200nm thick Nb film and the same line length and width. The predicted phase shift for our prototype is Δϕ≈30rad at 90GHz when biased at close to I∗ for Nb.
Single-photon direct detectors in the submillimeter, far-IR and mid-IR range are highly desirable for reaching the sensitivity permitted by the low background noise of cryogenic-optics space telescopes, such as envisioned in NASA’s Origins Space Telescope concept. When combined with arrays of integrated spectrometers they can enable revolutionary advances in astrophysical studies such as fast spectroscopic surveys of the high redshift universe from space. Coherent receivers, which are fundamentally limited by quantum vacuum noise are critical for high-spectral-resolution studies of molecular and atomic emission lines and can reveal the origins of galaxies, stars, and even life. They can also enable future space-based VLBI missions, such as the Photon Ring Telescope concept, to study black holes. I will review recent advances in key superconducting technologies being developed for the above areas, including single-photon far/IR Kinetic Inductance Detectors, integrated submillimeter spectrometers, and quantum-limited kinetic inductance amplifiers for microwave readout of detectors and for mm/sub-mm coherent receivers.
Abstract Superconducting parametric amplifiers offer the capability to amplify feeble signals with extremely low levels of added noise, potentially reaching quantum-limited amplification. This characteristic makes them essential components in the realm of high-fidelity quantum computing and serves to propel advancements in the field of quantum sensing. In particular, Traveling-Wave Parametric Amplifiers (TWPAs) may be especially suitable for practical applications due to their multi-Gigahertz amplification bandwidth, a feature lacking in Josephson Parametric Amplifiers (JPAs), despite the latter being a more established technology. This paper presents recent developments of the DARTWARS (Detector Array Readout with Traveling Wave AmplifieRS) project, focusing on the latest prototypes of Kinetic Inductance TWPAs (KITWPAs). The project aims to develop a KITWPA capable of achieving 20 dB of amplification. To enhance the production yield, the first prototypes were fabricated with half the length and expected gain of the final device. In this paper, we present the results of the characterization of one of the half-length prototypes. The measurements revealed an average amplification of approximately 9 dB across a 2 GHz bandwidth for a KITWPA spanning 17 mm in length.