Fiber-assisted single-photon spectrograph. M. Avenhaus, A. Eckstein, P. Mosley and C. Silberhorn in Opt. Lett. 34:2873 (2009). What the paper says!?
This is a paper on frequency-resolved photon correlations of single-photons and SPDC sources, developing a single-detector (APD) technique based on chirping from group-velocity dispersion to monitor all possible arrival times without the need for a multielement detector array. They thus «present a cost-effective solution [...] that enables the precise and efficient measurement of single-photon spectra»
Types of spectrometers:
Most types of spectrometers can be subdivided into two classes: scanning devices and spectrographs. Scanning spectrometers such as monochromators generally employ moving parts, but they are comparatively cheap to produce for they require only a single detector. Yet this comes at the expense of information, since they record only one spectral component at a time. Spectrographs typically consist of detector arrays such as CCDs to determine all spectral components simultaneously.
The quantum state they assume from their PDC
And this is the $|F(\omega_s,\omega_i)|^2$ they measure:
The two peaks are at different frequencies. There are no interesting correlations. The results are thus mainly on the technique itself and the new detector produced, rather than on properties of the source.
It has interesting references:
several groups have recently started to control [9–12] and characterize [13–17] the biphoton joint correlation spectra of parametric downconversion (PDC) sources.
Those include:
- Optimal photons for quantum-information processing. P. Rohde, T. Ralph and M. Nielsen in Phys. Rev. A 72:052332 (2005). on indinstinguishability.
And then on two-photon spectra of SPDC (Refs. [13-17]):
- Measurement of the spectral properties of the two-photon state generated via type II spontaneous parametric downconversion. Y.-H. Kim and W. Grice in Opt. Lett. 30:908 (2005).
- Joint spectrum of photon pairs measured by coincidence Fourier spectroscopy. W. Wasilewski, P. Wasylczyk, P. Kolenderski, K. Banaszek and C. Radzewicz in Opt. Lett. 31:1130 (2006).
- Joint spectrum mapping of polarization entanglement in spontaneous parametric down-conversion. H. Poh, C. Lum, I. Marcikic, A. Lamas-Linares and C. Kurtsiefer in Phys. Rev. A 75:043816 (2007).
- Spectral properties of entangled photon pairs generated via frequency-degenerate type-I spontaneous parametric down-conversion. S.-Y. Baek and Y.-H. Kim in Phys. Rev. A 77:043807 (2008).
- Joint Temporal Density Measurements for Two-Photon State Characterization. O. Kuzucu, F. Wong, S. Kurimura and S. Tovstonog in Phys. Rev. Lett. 101:153602 (2008).