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On-Chip Sensing of Hotspots in Superconducting Terahertz Emitters

Authors: Xianjing Zhou, Xu Han, Dieter Koelle, Reinhold Kleiner, Ulrich Welp, Xufeng Zhang and Dafei Jin

Nano Letters 2020 20 (6), 4197-4203

Abstract: Intrinsic Josephson junctions in high-temperature superconductor Bi2Sr2CaCu2O8+δ (BSCCO) are known for their capability to emit high-power terahertz photons with widely tunable frequencies. Hotspots, as inhomogeneous temperature distributions across the junctions, are believed to play a critical role in synchronizing the gauge-invariant phase difference among the junctions, so as to achieve coherent strong emission. In this paper, we demonstrate an on-chip in situ sensing technique that can characterize hotspot distributions on BSCCO.
This is achieved by fabricating a series of micro-nanosized “sensor” junctions on top of an “emitter” junction and measuring the critical current on the sensors versus the bias current applied to the emitter. This fully electronic on-chip design can enable efficient close-loop control of hotspots in BSCCO junctions and significantly enhance the functionality of superconducting terahertz emitters.


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