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Gaussian channels that are eventually entanglement breaking yet asymptotically nonclassicality saving
摘要： A complete classification of single-mode bosonic Gaussian channels on the basis of being quantum-limited or entanglement breaking under n-fold composition is obtained. Parametric forms for all single-mode bosonic Gaussian channels that remain quantum-limited under n-fold composition is obtained. It is shown that the obtained parametric forms of quantum-limited amplifier, attenuator, and singular noise channels are entanglement saving, i.e., they do not break entanglement under finite n-fold composition. All other single-mode bosonic Gaussian channels, quantum limited or not, are shown to be eventually entanglement breaking. Nonclassicality breaking under multiple composition of a single-mode bosonic Gaussian channel is also studied. We outline a family of single-mode bosonic Gaussian channels that are eventually entanglement breaking, but asymptotically nonclassicality saving. We illustrate examples of channels that are eventually nonclassicality breaking, asymptotically nonclassicality breaking, and asymptotically nonclassicality saving.
关键词： quantum-limited,entanglement breaking,asymptotically nonclassicality saving,Gaussian channels,nonclassicality breaking
更新于2025-09-23 15:21:01
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Optimizing the Nonlinearity and Dissipation of a SNAIL Parametric Amplifier for Dynamic Range
摘要： We present a quantum-limited Josephson-junction-based three-wave-mixing parametric amplifier, the superconducting nonlinear asymmetric inductive element (SNAIL) parametric amplifier (SPA), which uses an array of SNAILs as the source of tunable nonlinearity. We show how to engineer the nonlinearity over multiple orders of magnitude by varying the physical design of the device. As a function of design parameters, we systematically explore two important amplifier nonidealities that limit dynamic range: the phenomena of gain compression and intermodulation distortion, whose minimization are crucial for high-fidelity multiqubit readout. Through a comparison with first-principles theory across multiple devices, we demonstrate how to optimize both the nonlinearity and the input-output port coupling of these SNAIL-based parametric amplifiers to achieve higher saturation power, without sacrificing any other desirable characteristics. The method elaborated in our work can be extended to improve all forms of parametrically induced mixing that can be employed for quantum-information applications.
关键词： gain compression,Josephson-junction,three-wave-mixing,parametric amplifier,SNAIL,dynamic range,quantum-limited,intermodulation distortion
更新于2025-09-11 14:15:04