Quantum path control on high-order harmonic generation (HHG) from He atom by the spatial inhomogeneous laser field has been investigated. Results show that with the introduction of the spatial inhomogeneous field from the negative-r0 direction to the positive-r0 direction, a monotone enhancement of the harmonic cutoff is obtained and there is only the single short quantum path contributing to the maximum harmonic emission event. Time-frequency harmonic distributions and the time-dependent wave function have been shown to explain the harmonic spectra. Further, by properly adding a THz field, the harmonic intensity is enhanced by 2 orders of magnitude, and a smooth 1208 eV super-bandwidth can be obtained. Finally, by properly superposing the harmonics, a series of isolated 34 as pulses with wavelengths from 10nm to 1nm can be obtained.
