The delay line is a fundamental circuit design component which slows down a signal with minimal attenuation to provide delay effects, with applications that include interferometry and signal filtering. Cryogenic superconducting delay lines can be less lossy than their regularly conducting counterparts. Scientists can engineer microwave photos with coherence times of several microseconds (us), longer than current on-chip delays. We utilize the high dielectric constant (>10^4) of strontium titanate at cryogenic temperatures to slow own signal propagation on a coplanar waveguide. Here, we present a design for an on-chip 5 (us) superconducting delay line ad 5 GHz with small enough footprint to fit on-chip. This delay is more than 200 times longer than previously demonstrated while simultaneously more compact, enabling new regimes of interferometry. We also use simulations to characterize the sensitivity of the optimized design to alternative fabrication parameters. These designs may be useful for quantum information systems and integrated circuit design.
Adachi, Kazemi; Xu, Mingrui; and Tang, Hong
"Designing a Microsecond-Long On-Chip Microwave Delay Line Using SrTiO3 Dielectricity,"
The Yale Undergraduate Research Journal: Vol. 1
, Article 13.
Available at: https://elischolar.library.yale.edu/yurj/vol1/iss1/13