Quarton couplers for ultrafast superconducting qubit readout

Summary

Applies the quarton coupler to superconducting qubit readout, demonstrating via full master equation simulation that cross-Kerr coupling >200 MHz between a transmon qubit and a linearized transmon resonator enables 5 ns readout with >99% fidelity and >99.9% QND fidelity. The quarton’s positive ${\phi }^4$ potential cancels the negative self-Kerr of the readout transmon, effectively linearizing it while maintaining ultrastrong dispersive coupling to the qubit.

Cited In

• quarton-coupler