Parity-protected qubit based on Fourier engineering of the energy-phase relation | Nataliia Zhurbina (TU Delft | NL)

Errors arising from the quantum hardware in state-of-the-art superconducting qubits occur due to decoherence and sensitivity of the qubit to noise coming from the environment. Thus, to have more reliable quantum devices, we need to reduce the detrimental effects that the environment has on the qubit state. Protection against dielectric loss can be gained by the introduction of nonlinear elements allowing coherent tunnelling pairs of Cooper-pairs, which yields a nonlinear Josephson potential with only even harmonic terms. Such potential leads to nearly degenerate ground states, which are expected to suppress relaxation and dephasing of the qubit state. In this talk, we propose implementing such an element using Fourier engineering of the energy-phase relation, allowing the creation of a protected cos(2n) potential.