Cryogenic photoluminescence imaging system for nanoscale positioning of single quantum emitters

Abstract

We report a photoluminescence imaging system for locating single quantum emitters with respect to alignment features. Samples are interrogated in a 4 K closed-cycle cryostat by a high numerical aperture (NA=0.9, 100× magnification) objective that sits within the cryostat, enabling high efficiency collection of emitted photons without image distortions due to the cryostat windows. The locations of single In As/GaAs quantum dots within a > 50 μm × 50 μm field of view are determined with ≈ 4.5 nm uncertainty (one standard deviation) in a 1 s long acquisition. The uncertainty is determined through a combination of a maximum likelihood estimate for localizing the quantum dot emission, and a cross-correlation method for determining the alignment mark center. This location technique can be an important step in the high-throughput creation of nanophotonic devices that rely upon the interaction of highly confined optical modes with single quantum emitters.

Deterministic implementation of a bright, on-demand single-photon source with near-unity indistinguishability via quantum dot imaging

“…1(d)), and the corresponding total position uncertainty (< 10 nm), are similar to those achieved in Ref. [30]. As a consequence, the overall uncertainty in the quantum dot location within our fabricated devices is expected to mainly be limited by the uncertainty in the e-beam lithography alignment process, which is approximately 25 nm.…”

“…Significant improvement in the performance of this approach has been reported in Ref. [30], where use of a high numerical aperture objective within the sample’s cryogenic environment resulted in a reduced image acquisition time (now 1 s) and lower uncertainties in the localization of the QDs and alignment mark centers (factors of 10× and 4.7×, respectively).…”

“…1(b) shows an image acquired by applying the setup from Ref. [30] to our sample, which consists of 25.5 (15) λ /4-thick AlAs/GaAs mirror pairs which form the lower (upper) DBR, with metallic alignment marks fabricated on the sample surface by electron-beam (e-beam) lithography, thermal evaporation, and a lift-off process. While the signal-to-noise ratio of the QDs in Fig.…”

Combined Atomic Force Microscopy and Photoluminescence Imaging to Increase the Yield of Quantum Dot Photonic Devices

“…We use photoluminescence imaging as a high-throughput technique to locate single QDs with nanometer scale accuracy [5][6][7] , by imaging their emission, along with reflected light off reference alignment marks, onto a sensitive CCD camera. A schematic of the sample and an example of a photoluminescence image of the QD emission and alignment marks are shown in Figs.…”

“…1(a)-(b). We note that wide-field illumination (all QDs within a >50 um x 50 um area are excited) and multiplexed detection enable such an image to be acquired in a 1s long acquisition time, and due to the high signal-to-noise ratio in the obtained image, the QD location with respect to alignment marks can be determined with <5 nm uncertainty 7 . We then combine this optical technique with tapping mode AFM to study the sample's surface in correspondence to the area where the QD had been optically located 8 .…”