On-Chip Sensing of Hotspots in Superconducting Terahertz Emitters.
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.
['Zhou|Xianjing|X|', 'Han|Xu|X|', 'Koelle|Dieter|D|', 'Kleiner|Reinhold|R|', 'Welp|Ulrich|U|', 'Zhang|Xufeng|X|', 'Jin|Dafei|D|http://orcid.org/0000-0002-8035-3580']
terahertz emitter Josephson junction superconductor Nanosensor