Correction of spurious effects in the monochromatic controlled-squeezing gate

Develop a correction technique for the spurious effects induced by slowly varying time-dependent Hamiltonian terms in the monochromatic controlled-squeezing gate, for which the refocusing method used for the bichromatic conditional-squeezing gate is not applicable.

Background

The paper contrasts its bichromatic conditional-squeezing implementation with the previously proposed controlled-squeezing gate, which uses a monochromatic drive. Setting one drive amplitude to zero leaves each qubit branch with either a static or a slowly oscillating contribution, rather than both, so the symmetry required for the proposed refocusing protocol is lost.

The resulting slowly varying terms produce spurious effects, including deviations in the squeezing direction and induced phases. The authors state that no correction technique for these effects is known for the monochromatic implementation, leaving the development of such a technique unresolved.