Sub-Micrometer Epitaxial Josephson Junctions for Quantum Circuits
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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We present a fabrication scheme and testing results for epitaxial submicrometer Josephson junctions. The junctions are made using a high-temperature 1170 K via process yielding junctions as small as 0.8 microns in diameter by use of optical lithography. Sapphire AI2O3 tunnel-barriers are grown on an epitaxial ReTi multilayer base-electrode. We have fabricated devices with both Re and AI top electrodes. While room-temperature 295 K resistance versus area data are favorable for both types of top electrodes, the low-temperature 50 mK data show that junctions with the Al top electrode have a much higher subgap resistance. The microwave loss properties of the junctions have been measured by use of superconducting Josephson junction qubits. The results show that high subgap resistance correlates to improved qubit performance.
- Quantum Theory and Relativity
- Solid State Physics