Three-dimensional quantum imaging of dynamic targets using quantum compressed sensing.

Quantum imaging based on entangled light sources exhibits enhanced background resistance compared to conventional imaging techniques in low-light conditions. However, direct imaging of dynamic targets remains challenging due to the limited count rate of entangled photons. In this paper, we propose a quantum imaging method based on quantum compressed sensing that leverages the strong correlation characteristics of entangled photons and the randomness inherent in photon pair generation and detection. This approach enables the construction of a compressed sensing system capable of directly imaging high-speed dynamic targets. The results demonstrate that our system successfully achieves imaging of a target rotating at a frequency of 10 kHz, while maintaining an impressive data compression rate of 10-6. This proposed method introduces a pioneering approach for the practical implementation of quantum imaging in real-world scenarios.

High frequency near-infrared up-conversion single-photon imaging based on the quantum compressed sensing.

Infrared up-conversion single-photon imaging has potential applications in remote sensing, biological imaging, and night vision imaging. However, the used photon counting technology has the problem of long integration time and sensitivity to background photons, which limit its application in real-world scenarios. In this paper, a novel passive up-conversion single-photon imaging method is proposed, in which the high frequency scintillation information of a near infrared target is captured by using the quantum compressed sensing. Through the frequency domain characteristic imaging of the infrared target, the imaging signal-to-noise ratio is significantly improved with strong background noise. In the experiment, the target with flicker frequency on the order of GHz is measured, and the signal-to-background ratio of the imaging reaches up to 1:100. Our proposal greatly improved the robustness of near-infrared up-conversion single-photon imaging and will promote its practical application.

High-efficiency single-photon compressed sensing imaging based on the best choice scheme.

With single-photon sensitivity and picosecond resolution, single-photon imaging technology is an ideal solution for extreme conditions and ultra-long distance imaging. However, the current single-photon imaging technology has the problem of slow imaging speed and poor quality caused by the quantum shot noise and the fluctuation of background noise. In this work, an efficient single-photon compressed sensing imaging scheme is proposed, in which a new mask is designed by the Principal Component Analysis algorithm and the Bit-plane Decomposition algorithm. By considering the effects of quantum shot noise, dark count on imaging, the number of masks is optimized to ensure high-quality single-photon compressed sensing imaging with different average photon counts. The imaging speed and quality are greatly improved compared with the commonly used Hadamard scheme. In the experiment, a 64 × 64 pixels' image is obtained with only 50 masks, the sampling compression rate reaches 1.22%, and the sampling speed increases by 81 times. The simulation and experimental results demonstrated that the proposed scheme will effectively promote the application of single-photon imaging in practical scenarios.

Optical interference effect in the hybrid quantum dots/two-dimensional materials: photoluminescence enhancement and modulation.

The optical interference effect originating from the multiple reflections between the two-dimensional (2D) materials and the substrates has been used to dramatically enhance their Raman signal. However, this effect in the hybrid structures of colloidal quantum dots (QD) coupled to 2D materials is always overlooked. Here we theoretically prove that the photoluminescence (PL) intensities of the QD films in the QD-2D hybrid structures can be strongly enhanced and modulated by the optical interference effect between QD and 2D interfaces, breaking the inherent standpoint that PL intensities of the QD films are always prominently quenched in these hybrid structures. The theoretical predictions have been well confirmed by experimental measurements of PL properties of CdSe/ZnS and CdSeTe/ZnS QD on different 2D materials (such as WSe2, MoS2, and h-BN). PL intensities of these QD films have been periodically modulated from almost disappearing to strong enhancement (with the enhancement of about 6 times). The optical interference effect uncovered in this work enables a powerful method to manipulate the PL property of the QD films in the different QD-2D hybrid structures. These results can boost the optical performance of the QD-based electronic and optoelectronic devices in the hybrid QD-2D structures.

In situ manipulation of fluorescence resonance energy transfer between quantum dots and monolayer graphene oxide by laser irradiation.

The unique optical properties of solution-processable colloidal semiconductor quantum dots (QDs) highlight their promising applications in the next generation of optoelectronic and biomedical technologies. In order to optimize these applications, the tunability of QDs' optical properties is always highly desired. Although the tuning during synthesis stages has been intensively investigated, the in situ alteration after device fabrication is still limited. Here we report the tuning of the optical properties of CdSeTe/ZnS QDs through an in situ manipulation of fluorescence resonance energy transfer (FRET) between QDs and monolayer graphene oxide (GO). By increasing the acceptor's absorption ability of GO through laser irradiation, the efficiency of FRET between QDs and GO has been substantially improved from 29.7% to 70.0%. The corresponding energy transfer rate is enhanced by 5.5 times. These results can be well explored by a spectral overlap between the fluorescence emission of QDs and the absorption of original or reduced GO. Our scheme, with the features of in situ manipulation, high spatial resolution and wireless steering, enables the potential functionality of such hybrid structures in optoelectronic applications.

Versatile and scalable micropatterns on graphene oxide films based on laser induced fluorescence quenching effect.

Here we report on the preparation of quasi-homogeneous fluorescence emission from graphene oxide (GO) film by modifying the local optical properties through the laser-induced fluorescence quenching effect, and the fabrication of single and multilayer micropatterns on quasi-homogeneous GO films. The modification is stemming from the photoreduction of GO, where the reduction degree and fluorescence intensity can be precisely tuned by changing the laser power and irradiation duration. This versatile approach with a mask-free feature can be readily used to fabricate various complex microstructures on quasi-homogeneous GO film from single layer to multilayer in vertical scale, as well as micrometers to centimeters in lateral scale. The micropatterns with varied optical properties are promising for applications in information storage, display technology, and optoelectronic devices.

Modulation of the optical transmittance in monolayer graphene oxide by using external electric field.

Graphene oxide (GO) emerges as a functional material in optoelectronic devices due to its broad spectrum response and abundant optical properties. In this article, it is demonstrated that the change of optical transmittance amplitude for monolayer GO (mGO) could be up to 24.8% by an external electric field. The frequency harmonics for transmittance spectra are analyzed by use of Fast Fourier Transforms to give an insight into the modulation mechanism. Two physical models, the electrical permittivity and the sheet conductivity which linearly vary as the electric field, are proposed to response for the transmittance modulation. The model-based simulations agree reasonable well with the experimental results.

An electric field induced reversible single-molecule fluorescence switch.

We report that by applying an electric field to a single squaraine-derived rotaxane (SR) molecule on bare glass, the fluorescence can be completely quenched. The molecule undergoes a reversible fluorescence switch between a zero-field "on" state and a high-field "off" state, which is attributed to intramolecular electron transfer within the SR molecule.