R. Dolata

Superconducting microwave resonators with non-centrosymmetric nonlinearity

  1. M. Khabipov,
  2. V. Gaydamachenko,
  3. C. Kissling,
  4. R. Dolata,
  5. and A. B. Zorin
We investigated both theoretically and experimentally open-ended coplanar waveguide resonators with rf SQUIDs embedded in the central conductor at different positions. These rf SQUIDs
can be tuned by an external magnetic field and thus may exhibit the non-centrosymmetric nonlinearity of χ(2) type with suppressed Kerr nonlinearity. We demonstrated that this nonlinearity allows for efficient mixing of λ/2 and λ modes in the cavity and thus enables various parametric effects with three wave mixing. These effects are the second harmonic generation, the half tone generation, the parametric amplification in both degenerate and non-degenerate regimes and deamplification in degenerate regime.
arxiv pdf

Traveling-wave parametric amplifier based on three-wave mixing in a Josephson metamaterial

  1. A. B. Zorin,
  2. M. Khabipov,
  3. J. Dietel,
  4. and R. Dolata
. The amplifier consists"]of a microwave transmission line formed by a serial array of nonhysteretic one-junction SQUIDs. These SQUIDs are flux-biased in a way that the phase drops across the Josephson junctions are equal to 90 degrees and the persistent currents in the SQUID loops are equal to the Josephson critical current values. Such a one-dimensional metamaterial possesses a maximal quadratic nonlinearity and zero cubic (Kerr) nonlinearity. This property allows phase matching and exponential power gain of traveling microwaves to take place over a wide frequency range. We report the proof-of-principle experiment performed at a temperature of T = 4.2 K on Nb trilayer samples, which has demonstrated that our concept of a practical broadband Josephson parametric amplifier is valid and very promising for achieving quantum-limited operation.
arxiv pdf