Engineering pure 6 photon-interactions with a Josephson dipole - PART 2/2

Two or more superconducting qubits can be efficiently coupled by a driven nonlinear Josephson circuit capable of multi-photon interactions. Such a device typically consists of a flux-biased superconducting loop interrupted by one or more Josephson junctions, and couples to the external circuitry from a pair of its terminals. With adequate design, and choosing a proper flux-bias point, these dipoles can implement strong three-wave mixing Hamiltonians, resulting in a highly efficient photon swap between a pair of superconducting qubits. However, the capability of implementing pure higher order wave mixing has been limited by the difficulty of eliminating undesired Hamiltonian terms. In this talk, we will introduce a new device, which behaves as a pure 6-wave-mixing element. We will present preliminary theoretical and experimental results, discussing practical applications of such processes, including the simultaneous entanglement of 4 superconducting qubits.



Part 2 will present preliminary experimental results and applications of the 6-wave-mixing element.