  We demonstrate a high performance AOM based bi-frequency interferometer,
which can realize either beating or beating free interference for single photon
level quantum state. Visibility and optical efficiency of the interferometer
are (99.5 +- 0.2)% and (95 +- 1)%, respectively. The phase of the
interferometer is actively stabilized by using dithering phase locking scheme,
where the phase dithering is realized by directly driving the AOMs with
specially designed electronic signal. We further demonstrate applications of
the interferometer in quantum technology, including bi-frequency coherent
combination, frequency tuning and optical switching. These result show the
interferometer is a versatile device for multiple quantum technologies.
