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De-Zhong Cao

Publications and source records attributed to De-Zhong Cao.

18 recordsLinked to original sources
arXiv2024

Encryption in ghost imaging with Kronecker products of random matrices

By forming measurement matrices with the Kronecker product of two random matrices, image encryption in computational ghost imaging is investigated. The two-dimensional images are conveniently reconstructed with the pseudo-inverse matrices of the two random matrices. To suppress the noise, the method of truncated singular value decomposition can be applied to either or both of the two pseudo-inverse matrices. Further, our proposal facilitates for image encryption since more matrices can be involved in forming the measurement matrix. Two permutation matrices are inserted into the matrix sequence. The image information can only be reconstructed with the correct permutation matrices and the matrix sequence in image decryption. The experimental results show the facilitations our proposal. The technique paves the way for the practicality and flexibility of computational ghost imaging.

eess.IV↗
arXiv2024

Computational ghost imaging with hybrid transforms by integrating Hadamard, discrete cosine, and Haar matrices

A scenario of ghost imaging with hybrid transform approach is proposed by integrating Hadamard, discrete cosine, and Haar matrices. The measurement matrix is formed by the Kronecker product of the two different transform matrices. The image information can be conveniently reconstructed by the corresponding inverse matrices. In experiment, six hybridization sets are performed in computational ghost imaging. For an object of staggered stripes, only one bucket signal survives in the Hadamard-cosine, Haar-Hadamard, and Haar-cosine hybridization sets, demonstrating flexible image compression. For a handmade windmill object, the quality factors of the reconstructed images vary with the hybridization sets. Sub-Nyquist sampling can be applied to either or both of the different transform matrices in each hybridization set in experiment. The hybridization method can be extended to apply more transforms at once. Ghost imaging with hybrid transforms may find flexible applications in image processing, such as image compression and image encryption.

eess.IV↗
arXiv2024

Quantum projection ghost imaging

We establish a quantum theory of computational ghost imaging and propose quantum projection imaging where object information can be reconstructed by quantum statistical correlation between a certain photon number of bucket signal and DMD random patterns. The reconstructed image can be negative or positive depending on the chosen photon number. In particular, the vacuum state (zero-number) projection produces a negative image with better visibility and contrast-to-noise ratio. The experimental results of quantum projection imaging agree well with theoretical simulations and show that, under the same measurement condition, vacuum projection imaging is superior to conventional and fast first-photon ghost imaging in low-light illumination.

quant-ph↗
arXiv2022

Complex-amplitude Fourier single-pixel imaging via coherent structured illumination

We propose a method of complex-amplitude Fourier single-pixel imaging (CFSI) with coherent structured illumination to acquire both the amplitude and phase of an object. In the proposed method, an object is illustrated by a series of coherent structured light fields which are generated by a phase-only spatial light modulator, the complex Fourier spectrum of the object can be acquired sequentially by a single-pixel photodetector. Then the desired complex-amplitude image can be retrieved directly by applying an inverse Fourier transform. We experimentally implemented this CFSI with several different types of objects. The experimental results show that the proposed method provides a promising complex-amplitude imaging approach with high quality and a stable configuration. Thus, it might find broad applications in optical metrology and biomedical science.

physics.optics↗
arXiv2021

Full-color photon-counting single-pixel imaging

We propose and experimentally demonstrate a high-efficiency single-pixel imaging (SPI) scheme by integrating time-correlated single-photon counting (TCSPC) with time-division multiplexing to acquire full-color images at extremely low light level. This SPI scheme uses a digital micromirror device to modulate a sequence of laser pulses with preset delays to achieve three-color structured illumination, then employs a photomultiplier tube into the TCSPC module to achieve photon-counting detection. By exploiting the time-resolved capabilities of TCSPC, we demodulate the spectrum-image-encoded signals, and then reconstruct high-quality full-color images in a single-round of measurement. Based on this scheme, the strategies such as single-step measurement, high-speed projection, and undersampling can further improve the imaging efficiency.

physics.optics↗
arXiv2019

Is it necessary to achieve sub-wavelength interference with correlation?

We report an experimental demonstration of sub-wavelength interference without correlation. Typically, people can achieve sub-wavelength effect with correlation measurement no matter by using bi-photon or thermal light sources. Here we adopt a thermal light source. And we count the realizations in which the intensities of the definite symmetric points are above or below a certain threshold. The distribution of numbers of these realizations who satisfy the restriction will show a sub-wavelength effect. With proper constrictions, positive and negative interference patterns are demonstrated.

physics.optics↗
arXiv2018

Fractional-order correlation imaging with thermal light

In thermal light ghost imaging, the correlation orders were usually positive integers in previous studies. In this paper, we examine the fractional-order moments, whose correlation order are fractional numbers, between the bucket and reference signals in the ghost imaging system. The crucial step in theory is to determine the precise relation between the bucket signals and reference signals. We deduce the joint probability density function between the bucket and reference signals by regarding the reference signals as an array of independent stochastic variables. In calculating the fractional-order moments, the correlation order for the reference signals must be positive to avoid infinity. While the correlation order for the bucket signals can be positive or negative numbers. Negative (positive) ghost images are obtained with negative (positive) orders of the bucket signals. The visibility degree and signal-to-noise ratio of ghost images from the fractional-order moments are analysed. The experimental results and numerical simulations meet our analysis based on probability theory.

quant-ph↗
arXiv2013

Experimental Observation of Quantum Holographic Imaging

We report the first experimental observation of quantum holographic imaging with entangled photon pairs, generated in a spontaneous parametric down-conversion process. The signal photons play both roles of "object wave" and "reference wave" in holography but are recorded by a point detector providing only encoding information, while the idler photons travel freely and are locally manipulated with spatial resolution. The holographic image is formed by the two-photon correlation measurement, although both the signal and idler beams are incoherent. According to the detection regime of the signal photons, we analyze three types of quantum holography schemes: point detection, coherent detection and bucket detection, which can correspond to classical holography using a point source, a plane-wave coherent source and a spatially incoherent source, respectively. Our experiment demonstrates that the two-photon holography in the point detection regime is equivalent to the one-photon holography using a point source. Physically, the quantum holography experiment verifies that a pair of non-commutable physical quantities, the amplitude and phase components of the field operator, can be nonlocally measured through two-photon entanglement.

quant-ph↗
arXiv2009

Phase Reversal Diffraction in incoherent light

Phase reversal occurs in the propagation of an electromagnetic wave in a negatively refracting medium or a phase-conjugate interface. Here we report the experimental observation of phase reversal diffraction without the above devices. Our experimental results and theoretical analysis demonstrate that phase reversal diffraction can be formed through the first-order field correlation of chaotic light. The experimental realization is similar to phase reversal behavior in negatively refracting media.

quant-ph↗
arXiv2008

Spatial Interference: From Coherent To Incoherent

It is well known that direct observation of interference and diffraction pattern in the intensity distribution requires a spatially coherent source. Optical waves emitted from portions beyond the coherence area possess statistically independent phases, and will degrade the interference pattern. In this paper we show an optical interference experiment, which seems contrary to our common knowledge, that the formation of the interference pattern is related to a spatially incoherent light source. Our experimental scheme is very similar to Gabor's original proposal of holography[1], just with an incoherent source replacing the coherent one. In the statistical ensemble of the incoherent source, each sample field produces a sample interference pattern between object wave and reference wave. These patterns completely differ from each other due to the fluctuation of the source field distribution. Surprisingly, the sum of a great number of sample patterns exhibits explicitly an interference pattern, which contains all the information of the object and is equivalent to a hologram in the coherent light case. In this sense our approach would be valuable in holography and other interference techniques for the case where coherent source is unavailable, such as x-ray and electron sources.

physics.optics↗
arXiv2007

Complementarity in a macroscopic observation

Complementarity is usually considered as a phenomenon of microscopic systems. In this paper we report an experimental observation of complementarity in the correlated double-slit interference with a pseudothermal light source. The thermal light beam is divided into test and reference beams which are correlated with each other. The double-slit is set in the test arm, and the interference pattern can be observed in the intensity correlation between the two arms. The experimental results show that the disappearance of interference fringe depends on whether which-path information is gained through the reference arm. The experiment therefore witnesses the complementarity occurring in a macroscopic system.

quant-ph↗
arXiv2005

Sub-Rayleigh resolution of interference pattern with independent laser beams

We propose a new scheme to achieve sub-Rayleigh resolution of interference pattern with independent laser beams. We perform an experimental observation of a double-slit interference with two orthogonally polarized laser beams. The resolution of the interference pattern measured by a two-photon detection is doubled provided the two beams illuminate the double-slit with certain incident angles. The scheme is simple and can be in favor of both high intensity and perfect visibility.

physics.optics↗
arXiv2004

Manipulating Synchronous Optical Signals with a Double $Λ$ Atomic Ensemble

We analyze a double $Λ$ atomic configuration interacting with two signal beams and two control beams. Because of the quantum interference between the two $Λ$ channels, the four fields are phase-matched in electromagnetically induced transparency. Our numerical simulation shows that this system is able to manipulate synchronous optical signals, such as generation of optical twin signals, data correction, signal transfer and amplification in the atomic storage.

quant-ph↗
arXiv2004

Geometrical Optics in Coincidence Imaging System

We discuss the geometrical optics of coincidence imaging for two kinds of spatial correlations which are related to a classical thermal light source and a two-photon quantum entangled state.

quant-ph↗
arXiv2004

One-Photon and Two-Photon Double-Slit Interferences in Spontaneous and Stimulated Parametric Down-Conversions

We theoretically discuss one-photon and two-photon double-slit interferences for spontaneous and stimulated parametric down-conversions. We show that the two-photon sub-wavelength interference can exist in a general spontaneous parametric down-conversion (SPDC) for both type I and type II crystals. We propose an alternative way to observe sub-wavelength interference by a joint-intensity measurement which occurs for only type I crystal in a higher gain of SPDC. When a signal beam injects into the crystal, it may create two interference patterns by two stimulated down-converted beams, showing no sub-wavelength interference effect.

quant-ph↗
arXiv2003

Quantum Lithography in Macroscopic Observations

We study the generalized Young's double-slit interference for the beam produced in the spontaneously parametric down-conversion (SPDC). We find that the sub-wavelength lithography can occur macroscopically in both the two-photon intensity measurement and the single-photon spatial intensity correlation measurement. We show the visibility and the strength of the interference fringe related to the SPDC interaction. It may provide a strong quantum lithography with a moderate visibility in practical application.

quant-ph↗