Magnetic flux quantum periodicity of the frequency of the on-chip detectable electromagnetic radiation from superconducting flux-flow-oscillators
journal contributionposted on 08.10.2020, 08:59 by Boris ChescaBoris Chesca, Daniel John, Marat Gaifullin, Jonathan Cox, Aidan Murphy, Sergey SavelievSergey Saveliev, Christopher Mellor
Superconducting flux-flow-oscillators (FFOs) based on unidirectional flow of magnetic vortices in a single-long Josephson junction (JJ) and operating at 4.2 K are key elements of sub-terahertz integrated-receivers used in radio-astronomy and atmospheric science. Here, we report on the development of sub-terahertz FFOs based on parallel JJ-arrays made of YBa2Cu3O7−δ thin films. Sharp multiple flux-flow resonances were observed in the temperature range 77–89 K in asymmetric JJ-arrays, suggesting that they can operate as a narrow-band FFO in sub-terahertz integrated-receivers at more practical temperatures than 4.2 K. We detected electromagnetic radiation (EM) emitted by symmetric JJ-arrays in the range of 30–45 K using on-chip build superconducting detectors based on single JJs. For both asymmetric and symmetric JJ-arrays, the frequency f of the emitted radiation could be tuned continuously by an applied magnetic flux Φ with a one-flux-quantum Φ0 periodicity. Remarkably, since f can be tuned continuously, there are no gaps in the frequency range of the emitted EM. The fundamental Φ0-periodicity of f(Φ) is similar in nature to a SQUID's voltage response V(Φ) and, consequently, using high-performance magnetic flux-to-field conversion and readout techniques, a sensitive field-to-frequency magnetometer can be developed. Incorporated into non-accessible micro/nanostructures as a magnetic sensor, it would allow precise measurements of magnetic-fields from a distance, without the need to measure it locally as the radiation is detected remotely.
The research at Loughborough University (LU) was partially supported by the Higher Education Innovation Fund (HEIF) and Loughborough Enterprise Projects Group (EPG), EPG 101, 2017, LU code: S11519.