Laboratory 3-4: Confocal Microscope Imaging of Single-Emitter Fluorescence and Photon Antibunching Detection Using a Hanbury Brown & Twiss Setup

This lab had two objectives. First, we wished to image a variety of fluorescing single photon sources using a confocal microscopy setup. Second, we wished to detect photon antibunching using a Hanbury Brown & Twiss setup in at least one of the samples. We were able to successfully image samples of Single Walled Carbon Nanotubes, Nanodiamonds, Gold Nanoparticles, and Colloidal CdSe Quantum Dots, but, due to time constraints, we were not able to observe photon antibunching. Background The thing that we are most interested in within this lab is the nature of fluorescing single photon sources. Theoretically, single photon sources are interesting because of unexpected characteristics they exhibit like blinking and because of the single photon statistics they produce. Blinking is a phenomenon wherein single-emitters change emission intensity randomly and discontinuously. This is interesting because there is no definite theoretical or experimental understanding for why this happens, despite a significant amount of intense research (Krauss & Peterson, 2011). Statistically, single photon sources are interesting because of how they demonstrate the existence of a quantized electric field. Unfortunately, since we did not successfully observe antibunched photons or spend significant amounts of time on this topic in class, I will only briefly introduce this fascinating aspect of the coursework. In a classical electric field, the correlation between the intensities of light transmitted by a beamsplitter (IT) and reflected (IR) by the beamsplitter can be determined via the degree of second-order coherence, which is described by the relation gT,R (2) (τ) = < IT(t + τ)IR(t) > < IT(t + τ) >< IR(t) > where τ denotes the time delay between intensity measurements. For classical interpretations of the field, we expect that the beam of emitted light splits into two half as intense beams of light (IT and IR) upon hitting the beamsplitter such that each beam is incident upon the detectors at the same time, so the time delay τ should be 0. Theoretically, for classically behaving light,