We present a 1 Mpixel single-photon avalanche diode camera featuring 3.8 ns time gating and 24 kfps frame rate, fabricated in 180 nm CMOS image sensor technology. We designed two pixels with a pitch of 9.4 µm in 7 T and 5.75 T configurations respectively, achieving a maximum fill factor of 13.4%. The maximum photon detection probability is 27%, median dark count rate is 2.0 cps, variation in gating length is 120 ps, position skew is 410 ps, and rise/fall time is < 550 p s , all FWHM at 3.3 V excess bias. The sensor was used to capture 2D/3D scenes over 2 m with resolution (least significant bit) of 5.4 mm and precision better than 7.8 mm (rms). We demonstrate extended dynamic range in dual exposure operation mode and show spatially overlapped multi-object detection in single-photon time-gated time-of-flight experiments.

We present a novel guard-ring-sharing technique to push the limit of SPAD pixel miniaturization, and to demonstrate the operation of SPAD arrays with a 2.2 µm-pitch, the smallest ever reported. Device simulation and preliminary tests suggest that the optimized device design ensures the electrical isolation of SPADs with guard-ring sharing. 4×4 SPAD arrays with two parallel selective readout circuits are designed in 180 nm CMOS technology. SPAD characteristics for the pixel pitch of 2.2, 3, and 4 µm are systematically measured as a function of an active diameter, active-to-active distance, and excess bias. For a 4 µm-pitch, the fill factor is 42.4%, the maximum PDP 33.5%, the median DCR 2.5 cps, the timing jitter 88 ps, and the crosstalk probability is 3.57%, while the afterpulsing probability is 0.21%. Finally, we verified the feasibility of the proposed technique towards compact multi-megapixel 3D-stacked SPAD arrays.

With ionic liquid (IL) gating in electric-double-layer transistors (EDLTs), we report field effect operation and electronic state modulation in a layered material of ${\text{SnS}}_2$ , demonstrating that the EDLT is applicable to modifying the electronic properties of metal dichalcogenides. The IL-gated ${\text{SnS}}_2$ EDLTs allow us to realize high performance transistor operation and to achieve interfacial carrier accumulation to a level as high as $5.4\times {10}^{14}{\text{cm}}^{-2}$ , as quantitatively estimated from the Hall effect. A considerable decrease of the activation energy in temperature-dependent sheet resistance implies that liquid gating is an effective way to tune the electronic states of metal dichalcogenides at EDL interfaces.

Gate-defined quantum dots (QDs) are such a highly-tunable quantum system in which single spins can be electrically coupled, manipulated, and measured. However, the spins in gate-defined QDs are lacking its interface to free-space photons. Here, we verify that a circularly-polarized single photon can excite a single electron spin via the transfer of angular momentum, measured using Pauli spin blockade (PSB) in a double QD. We monitor the inter-dot charge tunneling which only occur when the photo-electron spin in one QD is anti-parallel to the electron spin in the other. This allows us to detect single photo-electrons in the spin-up/down basis using PSB. The photon polarization dependence of the excited spin state was finally confirmed for the heavy-hole exciton excitation. The angular momentum transfer observed here is a fundamental step providing a route to instant injection of spins, distributing single spin information, and possibly towards extending quantum communication.

We detect in real time interdot tunneling events in a weakly coupled two-electron double quantum dot in GaAs. At finite magnetic fields, we observe two characteristic tunneling times $T_d$ and $T_b$, belonging to, respectively, a direct and a blocked (spin-flip-assisted) tunneling. The latter corresponds to the lifting of a Pauli spin blockade, and the tunneling times ratio $\eta =T_b/T_d$ characterizes the blockade efficiency. We find pronounced changes in the behavior of $\eta$ upon increasing the magnetic field, with $\eta$ increasing, saturating, and increasing again. We explain this behavior as due to the crossover of the dominant blockade-lifting mechanism from the hyperfine to spin-orbit interactions and due to a change in the contribution of the charge decoherence.