Flux-driven Josephson parametric amplifier and preparation method thereof

Abstract

The invention provides a flux-driven Josephson parametric amplifier and a preparation method thereof. The preparation method comprises the following steps: forming an Nb / Al-AlOx / Nb laminated structureon the surface of a substrate; etching the Nb / Al-AlOx / Nb laminated structure to form a coplanar waveguide resonant cavity structure, a pumping line structure, a ground line structure, a signal inputwiring structure and a pumping input wiring structure, wherein an Nb / Al-AlOx / Nb Josephson junction is formed in the coplanar waveguide resonant cavity structure; forming an insulating layer on the surface of the structure, and etching the insulating layer to form a Josephson junction via hole, a grounding via hole, an input signal pin via hole and a pumping input pin via hole; and forming a superconducting thin film layer on the surface of the structure, etching the superconducting thin film layer to electrically connect the Josephson junction via hole with the grounding via hole, forming a grounding pin in the grounding via hole, forming an input signal pin in the input signal pin via hole, and forming a pumping input pin in the pumping input pin via hole.

Description

technical field [0001] The invention belongs to superconducting electronics, in particular to a flux-driven Josephson parametric amplifier and a preparation method thereof. Background technique [0002] As a new type of computing tool, quantum computer uses the superposition state principle of quantum mechanics and quantum entanglement characteristics, and has powerful parallel computing capabilities. Due to its low loss, good scalability, and compatibility with traditional micro-nano processing technology, superconducting qubits have become one of the most likely solutions for realizing quantum computers. In the qubit measurement experiment, in order to protect the state of the qubit, the measurement signal power is very small, and an external amplifier is needed at the output of the circuit to amplify the output signal. However, the noise temperature of commercial HEMTs (High Electron Mobility Transistors) is around 4K, which is difficult to be used for single shot read o...

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Problems solved by technology

The existing preparation methods have the following disadvantages: 1) Although the Al Josephson junction prepared by double-angle evaporation has fewer process steps, it is difficult to use plasma on the substrate or the surface of the Josephson junction before evaporating the film because the suspension bridge itself is relatively fragile. Etching for cleaning; 2) Using double-layer photoresist to prepare Al Josephson junction, there will be redundant patterns ( Image 6 (shown in the dotted line box) exists, which is not conducive to the realization of the scale of integrated circuits; 3) the superconducting transition temperature of Al thin film is low (about 1K), and it needs to work at a lower temperature

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