Individual laser-cooled atoms are delivered on demand from a single atom magneto-optic trap to a high-finesse optical cavity using an atom conveyor. Strong coupling of the atom with the cavity field allows simultaneous cooling and detection of individual atoms for time scales exceeding 15 s. The single atom scatter rate is studied as a function of probe-cavity detuning and probe Rabi frequency, and the experimental results are in qualitative agreement with theoretical predictions. We demonstrate the ability to manipulate the position of a single atom relative to the cavity mode with excellent control and reproducibility.

We use coherent excitation of 3-16 atom ensembles to demonstrate collective Rabi flopping mediated by Rydberg blockade. Using calibrated atom number measurements, we quantitatively confirm the expected √N Rabi frequency enhancement to within 4%. The resulting atom number distributions are consistent with an essentially perfect blockade. We then use collective Rabi π pulses to produce N=1, 2 atom number Fock states with fidelities of 62% and 48%, respectively. The N=2 Fock state shows the collective Rabi frequency enhancement without corruption from atom number fluctuations.

We demonstrate nondestructive (lossless) fluorescent state detection of individual neutral atom qubits trapped in an optical lattice. The hyperfine state of the atom is measured with a 95% accuracy and an atom loss rate of 1%. Individual atoms are initialized and detected over 100 times before being lost from the trap, representing a 100-fold improvement in data collection rates over previous experiments. Microwave Rabi oscillations are observed with repeated measurements of one and the same single atom.

The heat flux distribution beneath a superhydrophobic evaporating droplet has been explored. High speed, high resolution infrared thermography is employed to measure the heat transfer characteristic of the evaporating droplet. Optical imaging and analytical techniques are used the capture droplet dynamics over the course of its evaporation. The droplet evaporated with a receding contact line predominantly in the CCA regime. The peak local convective heat transfer was located at the triple contact line over the entire evaporation period. Peak and average heat fluxes were shown to increase as the evaporation proceeded due to the increasing contact line length density and liquid-gas interface temperature. The total thermal power across the solid-liquid interface decreased due to the decreasing solid-liquid surface area. The average heat flux to the evaporating droplet was shown to vary linearly with contact line length density.

An experimental investigation of the heat and mass transfer to an evaporating hydrophilic water droplet using thin-foil thermography and droplet shape analysis is reported. These results have been compared with that of a superhydrophobic evaporating droplet. The hydrophilic droplet initially evaporated with a pinned contact line before unpinning and evaporating with a receding contact line. The largest heat flux is observed at the contact line region for both droplets. The hydrophilic droplet evaporated 34% faster than its superhydrophobic counterpart due to its greater contact line length, liquid-gas interface temperature and solid-liquid surface area for the majority of its evaporation. In general, the hydrophilic droplet dissipated a greater total power due to its larger contact line length and solid-liquid surface area, while the superhydrophobic droplet had a greater average heat flux due to its larger contact line length density for the majority of its evaporation time. The average heat flux to the evaporating droplets was demonstrated to vary as a linear function of the contact line length density.

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Spray cooling is an attractive proposition for thermal dissipation due to its high efficiency and markedly lower power requirements than more conventional air cooling systems. The local convective heat flux to single source cone-jet electrospray using thin foil thermography has been investigated parametrically. Two-phase electrospray cooling using ethanol is explored for multiple nozzle sizes (D i = 0.33-1.37 mm), flow rates (Q = 2-16 µL min −1) and separation heights (H = 2.5-17.5 mm). The results shows two distinct regimes of electrospray cooling; evaporative and pool electrospray cooling. Cooling performance was shown to be dependent on separation height and flow rate. Nozzle size was shown not to be a significant parameter except for small dependency for the smallest nozzle size tested. Importantly, the results demonstrate that very high peak heat transfer enhancement of up to 18.71 times over natural convection can be achieved with electrospray cooling for exceptionally low flow rates (4 µL min −1).

We have realized a one dimensional optical lattice for individual atoms with a lifetime >300 s, which is 5 times longer than previously reported. In order to achieve this long lifetime, it is necessary to laser cool the at-oms briefly every 20 s to overcome heating due to technical fluctuations in the trapping potential. Without cooling, we observe negligible atom loss within the first 20 s followed by an exponential decay with a 62 s time constant. We obtain quantitative agreement with the measured fluctuations of the trapping potential and the corresponding theoretical heating rates.Comment: 4 pages, 5 figure