Single photon sources are desired for quantum computing and communication applications. Ideally, these sources would provide single photons on demand at the low-loss fiber optical communication wavelength of 1550 nm. Single Erbium ions provide a good candidate for such sources because they emit at the right wavelength and they are very stable, however, the challenges remain of isolating a single emitter, coupling its emission to optical fiber and enhancing its emission rate. Nanoaperture optical tweezers provide a pathway to solving these issues by trapping and identifying single emitters, enhancing their emission rate and providing efficient coupling to an optical fiber. Recently, we have made progress in each of these areas (trapping, enhancing and coupling), which will be reviewed in this talk.
Purpose: We present photon-counting computed tomography (PCCT) imaging of contrast agent triplets similar in atomic number (Z) achieved with a high-flux cadmium zinc telluride (CZT) detector.
Approach: The table-top PCCT imaging system included a 330-μm-pitch CZT detector of size 8 mm × 24 mm2 capable of using six energy bins. Four 3D-printed 3-cm-diameter phantoms each contained seven 6-mm-diameter vials with water and low and high concentration solutions of various contrast agents. Lanthanum (Z = 57), gadolinium (Gd) (Z = 64), and lutetium (Z = 71) were imaged together and so were iodine (Z = 53), Gd, and holmium (Z = 67). Each phantom was imaged with 1-mm aluminum-filtered 120-kVp cone beam x rays to produce six energy-binned computed tomography (CT) images.
Results:K-edge images were reconstructed using a weighted sum of six CT images, which distinguished each contrast agent with a root-mean-square error (RMSE) of <0.29 % and 0.51% for the 0.5% and 5% concentrations, respectively. Minimal cross-contamination in each K-edge image was seen, with RMSE values <0.27 % in vials with no contrast.
Conclusion: This is the first preliminary demonstration of simultaneously imaging three similar Z contrast agents with a difference in Z as low as 3.