Superconducting lumped-element travelling-wave parametric amplifiers
Doctoral thesis, 2024
In this thesis we explore, theoretically and experimentally, the requirements of developing an ideal low-noise amplifier for amplifying signals close to the quantum limit, such as signals used in superconducting quantum systems. The work is focused on how to enable exponential amplification in a travelling-wave parametric amplifier (TWPA), especially the ones based on three-wave mixing (3WM), although four-wave mixing (4WM) is also treated. These amplifiers are composed of a long chain of cascaded nonlinear inductors and capacitors that form a lumped-element transmission line. The nonlinearity of the inductive element in each unitcell provides the possibility of frequency mixing between the input signal and a strong pump. As a result, some of the pump energy may be transferred to the signal (desired) and to up-converted frequencies (undesired). We extend the theory of the continuous three-mode model for 3WM, both for a discrete chain at frequencies close to the spectral cutoff, as well as for small frequencies with an arbitrary amount of up-converted modes included. In both cases we find that the gain is significantly reduced compared to the prediction by the continuous three-mode model. Based on our findings, we propose a prototype that uses frequencies close to the cutoff frequency to prevent up-conversion, resonant phase matching for phase matching and impedance matching networks for impedance matching. The developed prototype shows very promising results, presented in one of the appended papers, with the possibility of achieving a high gain of ~20 dB in a wide band of several GHz, using only 200 unitcells. Finally we investigate the required peripheral circuitry to suppress leakage and provide isolation.
quantum-limited amplifier
SNAIL
parametric amplifier
rf-SQUID
parametric amplification
up-conversion
three-wave mixing
four-wave mixing
lumped-element
down-conversion
Josephson junction
travelling-wave parametric amplifier
resonant phase matching
Kollektorn, Kemivägen 9
Opponent: Prof. José Aumentado, NIST, USA
Author
Hampus Renberg Nilsson
Wallenberg Centre for Quantum Technology (WACQT)
Chalmers, Microtechnology and Nanoscience (MC2), Quantum Technology
Peripheral circuits for ideal performance of a traveling-wave parametric amplifier
Physical Review Applied,;Vol. 21(2024)
Journal article
High-Gain Traveling-Wave Parametric Amplifier Based on Three-Wave Mixing
Physical Review Applied,;Vol. 19(2023)
Journal article
Three-wave mixing traveling-wave parametric amplifier with periodic variation of the circuit parameters
Applied Physics Letters,;Vol. 122(2023)
Journal article
Daryoush Shiri, Hampus Renberg Nilsson, Pavan Telluri, Anita Fadavi Roudsari, Vitaly Shumeiko, Christian Fager, Per Delsing, Modeling and Harmonic Balance Analysis of Parametric Amplifiers for Qubit Read-out
Hampus Renberg Nilsson, Liangyu Chen, Giovanna Tancredi, Robert Rehammar, Daryoush Shiri, Filip Nilsson, Amr Osman, Vitaly Shumeiko, Per Delsing, A small footprint travelling-wave parametric amplifier with a high Signal-to-Noise Ratio improvement in a wide band
Modern information technology requires the development of a set of advanced tools for generation, processing, and detection of weak electromagnetic signals. An important part of such a toolbox is the use of extremely sensitive low-noise amplifiers. In superconducting quantum computers, for example, he signals typically only contain a few microwave photons, and to amplify such weak signals the noise added by the amplifier should also contain no more than a few photons. Ideally a suitable amplifier should only add the fundamentally required half a noise photon, also known as the quantum limit. Furthermore, the amplifier should not output anything but the amplified signal. Conventional semiconducting amplifiers add up to 10-40 noise photons, and they output noise in the direction of the signal source. Therefore they are not suitable for quantum computers. Parametric amplifiers, on the other hand, are a known class of theoretically quantum-limited devices. These devices use a parametric resonance effect for signal amplification. In this project we investigate a particular implementation of a parametric amplifier, the travelling-wave parametric amplifier (TWPA). The TWPA employs a nonlinear interaction of electromagnetic waves in a waveguide to amplify weak signals. The device we study operates at microwave frequencies and ultra-low temperatures, and consists of a chain of hundreds of superconducting tunnel junctions embedded in a transmission line. An established theory predicts a very high gain for such devices, but in experiments the resulting gain is significantly smaller. In this work we investigate the physical reasons for such a discrepancy and propose ways to solve the problem. Our study reveals that one of the major reasons for poor amplifier performance is the generation of parasitic modes that take energy away from the useful modes involved in the amplification process. Another problem is that the amplifier lacks isolation and leaks unwanted modes. Therefore we also investigate the required peripheral circuitry to suppress the leakage and provide isolation.
Areas of Advance
Nanoscience and Nanotechnology
Roots
Basic sciences
Driving Forces
Innovation and entrepreneurship
Subject Categories
Nano Technology
Infrastructure
Nanofabrication Laboratory
ISBN
978-91-8103-104-1
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5562
Publisher
Chalmers
Kollektorn, Kemivägen 9
Opponent: Prof. José Aumentado, NIST, USA