QC-S5 Fast Cars: Practical, Pump-Efficient, and Embedded Cavity-Based Parametric Amplifiers
Abstract
Parametric amplifiers (paramps) remain vital components of superconducting quantum information processors, with prominent recent quantum computing results (including error correction efforts in surface codes) relying on high fidelity, QND readouts via parametric amplification. An ideal amplifier possesses large instantaneous bandwidth, high saturation power to process large and/or multiple input signals, and is quantum limited to add minimum noise to signals it processes. Lastly, an ideal amplifier should also be directional to avoid unwanted back-action on the system (often a qubit) being measured. Though there has been recent progress on all of these figures of merit, at present no single microwave paramp possesses all these virtues. Traveling wave parametric amplifiers (TWPAs) hold the edge in instantaneous bandwidth, and thus find widespread use. Their primary limitations are (1) noise, as they add several times more noise than cavity-based parametric amplifiers, and (2) the practical requirement for circulators to protect the system being measured. Cavity-based amplifiers, on the other hand, have been recently used to demonstrate efficient, truly-directional amplification and qubit readout by co-PI Aumentado. This method of operation relies on multiple parametric drives among several modes of the device, and as such has proven to have substantial costs in terms of operation and circuit design, which currently limits wide-spread implementation. Meanwhile, non-directional amplifiers have demonstrated superior saturation powers in both kinetic-inductance based devices and this teamÕs own RF SQUID array amplifier prototype, which achieves > -90 dBm saturation power. This improvement, however, requires a daunting increase in pump power. In this proposal, we propose three interconnected projects to both better understand the physics which limits paramps as well as produce practical, highly usable devices which can propel progress in superconducting quantum information processors. The first project, led by co-PI Aumentado will combine our advance in saturation power with recent theory results on how to broaden the bandwidth of cavity-based amplifiers to produce truly robust and practical non-directional amplifiers. Our targets are one- and two-mode devices with > 200 MHz of instantaneous bandwidth and saturation power > -100 dBm, which, together with cavity-based amplifiersÕ superior noise performance, can compete favorably with TWPAs in many applications. We will also use these devices to study intermodulation products arising from measuring multiple tones at once. These amplifiers will be made available to other performers. In the second project, led by Pekker and Hatridge, we will engineer the non-linearity of single-mode paramps to attempt to increase the efficiency with which paramps convert pump photons to amplified signal photons, which will allow us to maintain or increase amplifier saturation power while reducing pump-induced cryostat heating. Finally, Hatridge and TŸreci will develop an Ôembedded amplifierÕ which creates directional amplification by applying time-separated parametric pulses to a SNAIL-based nonlinear mode and linear output mode which are directly linked to the a qubitÕs readout mode. This will allow us to operate without circulators between qubit and amplifier while avoiding the complex requirements of current multi-parametric directional amplifier, yielding high-performance readout which can be readily added to many experiments.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2023
- Source ID
- W911NF2310252
Entities
People
- Michael Hatridge
Organizations
- Army Contracting Command
- National Security Agency
- University of Pittsburgh