Optical lithography implementation of a non-degenerate parametric amplifier based on two coupled Josephson junction arrays

Quantum-limited amplification is a prerequisite for the implementation of state-of-the-art quantum information processing schemes with superconducting quantum bits. We present the implementation of a parametric amplifier which consists of two identical, capacitively coupled Josephson junction array resonators, referred to as Dimer Josephson Junction Array Amplifier (DJJAA). The Josephson Junction arrays are sufficiently long (10³ junctions) that several eigenmodes are found on the linear part of the dispersion relation and can be used for amplification. Due to the shared coupling capacitance between the arrays, their spectra hybridize to symmetric and antisymmetric pairs of modes [Eichler et al., PRL 113 (2014)], with a level splitting up to several hundreds of MHz. We observe non-degenerate amplification in excess of 20 dB, instantaneous bandwidth of approx. 10 MHz, 1 GHz frequency tunability, and dynamic range exceeding the single-photon regime. All structures are fabricated using standard two step optical lithography, making the DJJAA fabrication procedure easily accessible to a wide community.