A Rotary Echo Flux Qubit

Flux qubits can have long T1 decay times due to nearly disjoint support of their flux basis wavefunctions. However the coupling of flux noise to circulating currents can lead to short dephasing times. This talk describes a qubit that utilizes a rotary echo control technique to maintain long T1 times yet also generating insensitivity to flux noise below a cutoff frequency. As the majority of the flux noise is low frequency in nature, this generates a qubit design capable of achieving high coherence.