  In recent years, quantum Fourier transform infrared (QFTIR) spectroscopy
emerged as an alternative to conventional spectroscopy in the mid-infrared
region of the spectrum. By harnessing induced coherence and spectral
entanglement, QFTIR offers promising potential for the practical detection of
organic gasses. However, little research was conducted to bring QFTIR
spectrometers closer to domestic or in-field usage. In this work, we present
the first use of a QFTIR spectrometer for open-path detection of multiple
interfering organic gases in ambient air. The accurate identification of
mixtures of acetone, methanol, and ethanol vapors is demonstrated with a QFTIR
spectrometer. We achieved this breakthrough by building a nonlinear Michelson
interferometer with 1.7m-long arms to increase the absorption length, coupled
with analysis techniques from differential absorption spectroscopy. The
evolution of different gasses' concentrations in ambient air was measured
through time. These results constitute the first use-case of a QFTIR
spectrometer as a detector of organic gasses, and thus represent an important
milestone towards the development of such detectors in practical situations.
