Maximized dynamic range over a continuum of operating frequencies with Gradiometric SNAILs – based parametric amplifier

Superconducting quantum-limited parametric amplifiers are key devices for high fidelity readout of superconducting qubits. Recently, these amplifiers have been implemented with SNAILs as flux-tunable nonlinear elements in order to offer a maximized dynamic range when flux-biased at a Kerr-free point. However, for a SNAIL – based parametric amplifier, a Kerr-free point corresponds to a single value of operating frequency, limiting the range of available high performances operations. In this work, we demonstrate how to break this constraint with a Gradiometric SNAIL, a doubly-flux biased nonlinear element with enhanced tuning of nonlinear processes. When employed to implement parametric amplifiers, Gradiometric SNAILs provide enough tuning capabilities to maximize dynamic range over a continuum of operating resonance frequencies. Experimental results on Gradiometric SNAIL – based parametric amplifiers will be shown and discussed.