Maintaining high Q-factor of superconducting YBa$_2$Cu$_3$O$_{7-x}$ microwave cavity in a high magnetic field

Abstract

A high Q-factor microwave resonator in a high magnetic field could be of great use in a wide range of fields, from accelerator design to axion dark matter search. The natural choice of material for the superconducting cavity to be placed in a high field is a high temperature superconductor (HTS) with a high critical field. The deposition, however, of a high-quality, grain-aligned HTS film on a three-dimensional surface is technically challenging. We have fabricated a polygon-shaped resonant cavity with commercial YBa2Cu3O7−x (YBCO) tapes covering the entire inner wall and measured the Q-factor at 4 K at 6.93 GHz as a function of an external DC magnetic field. We demonstrated that the high Q-factor of the superconducting YBCO cavity showed no significant degradation from 1 T up to 8 T. This is the first indication of the possible applications of HTS technology to the research areas requiring a strong magnetic field at high radio frequencies.

First Results from an Axion Haloscope at CAPP around 10.7 μeV

“…We minimized the physical temperature of the cavity down to 38 mK, the coldest axion dark matter experiment to date. We obtained the result with a high electron mobility transistor (HEMT) amplifier with a noise temperature around 1 K. The subsequent use of a near quantum noise limited Josephson parametric amplifier (JPA), employing the latest R&D results of CAPP [18,19], improved the scanning speed by more than an order of magnitude in the ongoing research.…”

Revisiting the detection rate for axion haloscopes

“…(1.1) and (1.4) always equals to Q c and Q l since the typical cavity quality factors of Q c ≈ 10 4 ∼ 10 5 are much smaller than the axion quality factor of Q a ≈ 10 6 [20]. However, the recent developments in superconducting (SC) technology and its applications to radio-frequency science are likely to dramatically increase the quality factor of resonant cavities even under strong magnetic fields [21,22]. Furthermore, the system noise power in eq.…”

Search for invisible axion dark matter of mass m$_a=43~μ$eV with the QUAX--$aγ$ experiment

“…[16,24] and Ref. [25]) or dielectrics [26,27]. On the amplification side, state-of-art experiments operate at the SQL − with SQUIDs [6,28] or Josephson Parametric Amplifiers (JPAs) [7] − while there is an attempt to circumvent it using squeezed-state receivers [8].…”