How to achieve IQ like this?

Any micro-four-thirds camera with a fast prime will give you the image quality you're looking for. You can pick up an olympus e-pl1 and the panasonic 20mm f1.7 for probably $500 together. You can also pick up tons of great old Canon and Nikon lenses that mount to m43 with an adapter. The larger sensor and wide apertures will let you isolate subjects and get some nice background blur going. The 20mm at least has great sharpness.

The next meaningful step in IQ is probably to jump to a $1000 (body only) DSLR like the Nikon D700. Depends how much you're willing spend/carry.