Seminar: Electro-Optics and Microelectronics Seminar
Superconducting Detectors and Sources
Date:
September,02,2024
Start Time:
14:30 - 15:30
Location:
1061, Meyer Building
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Lecturer:
Dima Panna
Research Areas:
| Superconductors are an important material platform for various applications and fundamental studies in condensed matter physics. They are employed in radiation detectors, and sources, transistors, classical and quantum logic gates, optical amplifiers, and waveguides. Quantum and classical communication channels require fast, low-jitter, low dark count, and high quantum efficiency detectors operating ideally at temperatures above liquid nitrogen. Low-Tc superconducting nanowire single-photon detectors (SNSPD) revolutionized the field of astronomy and planetary sciences, medical imaging, and molecular physics, as well as quantum communication and optics. The main disadvantage of the detectors based on the low-Tc superconductors is the closed-cycle cryogenic cooling requirement below the temperature of liquid helium (4K). In my research, I developed and investigated superconducting bolometers and nanowires using high-Tc superconductors. I showed that these detectors based on Yba2Cu3O(7-δ) (YBCO) can operate at temperatures above 77K with responsivity at visible, NIR, and IR wavelengths. Two detector types – bolometric (nano) and ultrafast (micro) wires were designed, fabricated, and fully characterized including speed, jitter, spectral sensitivity, NEP, and minimal detection levels. Superconducting detectors offer extremely high electro-thermal coefficients at temperatures close to the superconducting transition region. When the wire temporal performance is important a different detector type based on a microwire bridge can achieve ultrafast response and picosecond level jitter. The detection mechanism is based on the hotspot generation by photon absorption resulting in the appearance of the normal resistive region and current density redistribution in other regions of the wire. The minimal achieved jitter value for the microwire bridge detector was about 100ps, while the rise and fall times were limited by the RF electronics. Superconducting sources are key ingredients in the realization of quantum communication channels which rely on the generation of entangled photon pairs. While conventional methods rely on non-linear processes, isolated quantum dots, or atomic emitters we suggest a generation scheme based on the superconducting-semiconductor junctions using Cooper-pair entanglement. In my research, I demonstrated Cooper pair injection in various superconducting-semiconducting hybrid structures including high-Tc and low-Tc superconductors and a broad range of semiconducting materials. In particular, I demonstrated Cooper-pair injection and the proximity effect of the Nb in two-dimensional TMD material WS2. Moreover, their atomically sharp and ultra-thin nature is particularly attractive in the realization of the light-emitting sources based on the proximity effect, where penetration depth is limited to a few tens of nanometers. The ability to manipulate the chemical potential of the 2D semiconductor via external gating enables the realization of the superconducting field-effect transistors and controlled Josephson junctions.Ph.D. under supervision of Prof. Alex Hayat. |