P. Jung

Design and experimental study of superconducting left-handed transmission lines with tunable dispersion and improved impedance match

  1. E. A. Ovchinnikova,
  2. S. Butz,
  3. P. Jung,
  4. V. P. Koshelets,
  5. L. V. Filippenko,
  6. A.S. Averkin,
  7. S. V. Shitov,
  8. and A. V. Ustinov
We continue detailed study of microwave properties of a superconducting left-handed tunable CPW transmission line (LHTL). The line consists of a central conductor, loaded with series
of Josephson junctions as fixed inductors; the line is shunted with SQUIDs as tunable inductors. The inductance of the SQUIDs is varied in the range of 0.08-0.5 nH by applying an external dc magnetic field. The circuit is designed to have left- and right-handed transmission bands separated by a variable rejection band. At zero magnetic field, we observed only one pass-band between 8 and 10 GHz within the frequency range of 8-12 GHz. The rejection band is anticipated to appear between 10 GHz and 11 GHz by design, and it has been detected in our previous work. To solve the problem of standing waves and RF leak in measurements of our experimental 20-cell LHTL, we have designed a high-ratio (5-50 Ohm) wideband (8-11 GHz) impedance transformer integrated at the chip, along with improved sample holder. The experimental data are compared with numerical simulations.
arxiv pdf

Anisotropic rare-earth spin ensemble strongly coupled to a superconducting resonator

  1. S. Probst,
  2. H. Rotzinger,
  3. S. Wünsch,
  4. P. Jung,
  5. M. Jerger,
  6. M. Siegel,
  7. A. V. Ustinov,
  8. and P. A. Bushev
Interfacing photonic and solid-state qubits within a hybrid quantum architecture offers a promising route towards large scale distributed quantum computing. Ideal candidates for coherent
qubit interconversion are optically active spins magnetically coupled to a superconducting resonator. We report on a cavity QED experiment with magnetically anisotropic Er3+:Y2SiO5 crystals and demonstrate strong coupling of rare-earth spins to a lumped element resonator. In addition, the electron spin resonance and relaxation dynamics of the erbium spins are detected via direct microwave absorption, without aid of a cavity.
arxiv pdf