Quantum Fourier-transform infrared spectroscopy in the fingerprint region

Abstract

Infrared quantum absorption spectroscopy is one of the quantum sensing techniques, by which the infrared optical properties of a sample can be estimated through visible or near infrared photon detection without need for infrared optical source or detector, which has been an obstacle for higher sensitivity and spectrometer miniaturization. However, experimental demonstrations have been limited to wavelengths shorter than 5 µm or in the terahertz region, and have not been realized in the so-called fingerprint region of 1500–500 cm−1 (6.6 to 20 µm), which is commonly used to identify chemical compounds or molecules. Here we report the experimental demonstration of quantum Fourier-transform infrared (QFTIR) spectroscopy in the fingerprint region, by which both absorption and phase spectra (complex spectra) can be obtained from Fourier transformed quantum interferograms obtained with a single pixel visible-light detector. As demonstrations, we obtained the transmittance spectrum of a silicon wafer at around 10 µm (1000 cm−1) and complex transmittance spectrum of a synthetic fluoropolymer sheet, polytetrafluoroethylene, in the wavelength range of 8 to 10.5 µm (1250 to 950 cm−1), where absorption due to stretching modes of C-F bonds is clearly observed. These results open the way for new forms of spectroscopic devices based on quantum technologies.

Exploring Quantum Sensing Potential for Systems Applications

“…It imposes a practical limit on applications that require high-resolution images. Attempts to improve and enhance image quality and resolution focused on employing a pseudo-inverse ghost imaging technique via a sparsity constraint [47], employing a Schmidt decomposition for image enhancement [48], and imaging based on Fourier spectrum acquisition [49].…”

Acyclic Triterpenoids from Alpinia katsumadai Seeds with Proprotein Convertase Subtilisin/Kexin Type 9 Expression and Secretion Inhibitory Activity

“…Furthermore, unlike ECD, VCD spectroscopy does not require chromophores for analyzing the compound of interest. – For these reasons, after experimental measurement and calculation of VCD, experimental and calculated VCD and IR spectral data of 1 were compared within the range from 1500 to 1100 wavenumbers (cm –1 ), which is referred to as the fingerprint region (Figures A, S79, and S80). Due to these advantages, the experimental and calculated VCD and IR spectral data of compound 1 were compared specifically in the fingerprint region ranging from 1500 to 1100 wavenumbers (cm –1 ) (Figures A, S79, and S80). After the comparison, the VCD and IR data demonstrated agreement with the (3 R ,20 S ) -1 configuration, confirming that compound 1 was (3 R ,20 S )-2,3,20-trihydroxy-2,6,10,15,19,23-hexamethyl-tetracosa-6,10,14,18,22-pentaene.…”

Robust Quantum Feature Selection Algorithm

“…The quantum fourier transform does the same mapping as the classical fourier transform [16] [17]. It is defined as a unitary operator F acting on n quantum bits.…”