Cesium lead halide perovskite quantum dots (PQDs) provide an extraordinary solution-based method to fabricate high-performance solar cells, luminescent lightemitting devices, highly coherent single-photon quantum sources, and studying quantum mechanisms for quantum computing technologies. In these applications, characterizing heterogeneity and observing coupling between dots is critical. In this thesis, we use double-nanohole (DNH) optical tweezers to realize single trapping for PQDs in solution. We can estimate the size of an individual dot by studying thermal fluctuations and correlate it to emission energy shifts from quantum confinement. Based on single trapping experiment, we also use the same setup to capture a second dot by using the DNH tweezer and observe a systematic red-shift of 1.1 ± 0.6 meV in the emission wavelength upon multiple repeated measurements. Theoretical analysis shows that the experiment results are consistent with Förster resonant energy transfer (FRET), which has been proposed to obtain entanglement between colloidal quantum dots for quantum information applications. The value of the FRET is quite large when compared with the confined quantum dots and it is exciting for FRET to generate entanglement for quantum information processing applications (e.g. quantum logic gates). In the thesis, we have proved that our method allows for in-situ sizing of individual PQDs for the first time, which is relevant for improving the growth process and does not require expensive techniques. It also enables future work to search and select two dots that are nominally identical. Optical trapping with DNHs fabricated using colloidal lithography can be used to control PQD growth in-situ and enables further studies of the coupling of quantum dots at a small distance with quantum information applications. / Graduate