Photonics

Research

11 pages, 7845 KiB

Open AccessArticle

Amplified Nonreciprocal Reflection in a Uniform Atomic Medium with the Help of Spontaneous Emissions

by Xinyu Lin, Xinfu Zheng, Yue Geng, Guanrong Li, Qiongyi Xu, Jinhui Wu, Dong Yan and Hong Yang

Photonics 2024, 11(4), 389; https://doi.org/10.3390/photonics11040389 - 22 Apr 2024

Viewed by 305

Abstract

It is important to elaborate on versatile strategies for achieving the perfect nonreciprocal reflection amplification, which is the key technology of high-quality nonreciprocal photonic devices. In this work, we ingeniously design a coherent four-level N-type atomic system to harness the nonreciprocal light [...] Read more.

It is important to elaborate on versatile strategies for achieving the perfect nonreciprocal reflection amplification, which is the key technology of high-quality nonreciprocal photonic devices. In this work, we ingeniously design a coherent four-level N-type atomic system to harness the nonreciprocal light amplification, in which the uniform distribution of atoms is driven by two strong coupling fields and a weak probe field. In our regime, the strength of the two control fields is designed with linear variation along the x direction to destroy the spatial symmetry of the probe susceptibility, leading to the nonreciprocity of the reflection. In particular, the closed-loop transitions to amplify the probe field are due to the combined effect of the control fields and spontaneous emissions. The numerical simulation indicates that the perfect nonreciprocal reflection amplification can be realized and modulated by the appropriate settings of the control fields and the detuning,

Δ_{c}

. Our results will open a new route toward harnessing nonreciprocity, which can provide more convenience and possibilities in experimental realization. Full article

(This article belongs to the Special Issue Optical Quantum System)

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13 pages, 414 KiB

Open AccessArticle

Dissipation-Induced Photon Blockade in the Anti-Jaynes–Cummings Model

by Biao Huang, Cuicui Li, Bixuan Fan and Zhenglu Duan

Photonics 2024, 11(4), 369; https://doi.org/10.3390/photonics11040369 - 15 Apr 2024

Viewed by 453

Abstract

Due to the fundamental differences between the quantum world and the classical world, some phenomena, such as entanglement and wave–particle duality, only exist in the quantum realm. These peculiar phenomena cannot be demonstrated by classical means: Quantum networks, quantum cryptography, and quantum precision [...] Read more.

Due to the fundamental differences between the quantum world and the classical world, some phenomena, such as entanglement and wave–particle duality, only exist in the quantum realm. These peculiar phenomena cannot be demonstrated by classical means: Quantum networks, quantum cryptography, and quantum precision measurements all require quantum sources. Photons are particularly well-suited as quantum sources owing to their minimal interaction with the environment, high flight speed, and ease of interaction with current typical quantum systems. Single-photon sources include pulsed excitation of quantum dots, spontaneous parametric down-conversion, and photon blockade. Herein, we propose that the anti-Jaynes–Cummings model can induce a pronounced photon antibunching effect when subjected to intense cavity dissipation. Similar to the photon blockade caused by strong photon–photon interaction, this antibunching effect is referred to as ’dissipation-induced blockade’. Our findings indicate that the minimum decay rate of a qubit, coupled with a high decay rate for photons, is conducive to achieving strong antibunching within the system. Notably,

g^{(2)} (0) < g^{(2)} (τ)

, a characteristic of photon antibunching, is only valid under the optimal condition

Δ = 0

. Conversely,

g^{(2)} (0) < 1

is satisfied across all parameters, indicating that

g^{(2)} (0) < 1

is not a prerequisite for antibunching in the anti-Jaynes–Cummings model. Moreover, under the optimal conditions of the antibunching effect, the average photon number attains its peak value. Consequently, the current anti-Jaynes–Cummings model is promising for developing single-photon sources characterized by excellent purity and average photon number. Full article

(This article belongs to the Special Issue Optical Quantum System)

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12 pages, 286 KiB

Open AccessArticle

Quantum Dissipative Adaptation with Cascaded Photons

by Thiago Ganascini, Thiago Werlang and Daniel Valente

Photonics 2024, 11(1), 41; https://doi.org/10.3390/photonics11010041 - 31 Dec 2023

Cited by 1 | Viewed by 809

Abstract

Classical dissipative adaptation is a hypothetical non-equilibrium thermodynamic principle of self-organization in driven matter, and it relates transition probabilities with the non-equilibrium work performed by an external drive on dissipative matter. Recently, the dissipative adaptation hypothesis was extended to a quantum regime with [...] Read more.

Classical dissipative adaptation is a hypothetical non-equilibrium thermodynamic principle of self-organization in driven matter, and it relates transition probabilities with the non-equilibrium work performed by an external drive on dissipative matter. Recently, the dissipative adaptation hypothesis was extended to a quantum regime with a theoretical model where only one single-photon pulse drives each atom of an ensemble. Here, we further generalize that quantum model by analytically showing that N cascaded single-photon pulses driving each atom still fulfill a quantum dissipative adaptation. Interestingly, we find that the level of self-organization achieved with two pulses can be matched with a single effective pulse only up to a threshold, above which the presence of more photons provides unparalleled degrees of self-organization. Full article

(This article belongs to the Special Issue Optical Quantum System)

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7 pages, 1344 KiB

Open AccessCommunication

Electromagnetically Induced Transparency Spectra of ⁶Li Rydberg Atoms

by Meimei Wu, Xin Bao, Shuxian Yu, Licheng Yi, Pingshuai Ren, Shujin Deng and Haibin Wu

Photonics 2023, 10(12), 1367; https://doi.org/10.3390/photonics10121367 - 12 Dec 2023

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Abstract

Rydberg atoms possess highly excited valence electrons that are far away from atomic cations. Compared with ground states, Rydberg states are excited states with a high principal quantum number n that exhibit large electric dipole moments and have a variety of applications in [...] Read more.

Rydberg atoms possess highly excited valence electrons that are far away from atomic cations. Compared with ground states, Rydberg states are excited states with a high principal quantum number n that exhibit large electric dipole moments and have a variety of applications in quantum information processing. In this communication, we report the measurement of the

^{6}

Li Rydberg excitation spectrum by ladder-type electromagnetically induced transparency (EIT) in a vapor cell. The 2

p \to n s / n d

EIT spectra were recorded by sweeping the frequency of an ultraviolet Rydberg pumping laser while keeping the probing laser resonant to the

2 s \to 2 p

transition. All lasers were locked on an ultrastable optical Fabry-Pérot cavity and measured by an optical frequency comb. Our results provide valuable information to precisely determine quantum defects and enable novel experiments with Rydberg-dressed ultracold Fermi gases. Full article

(This article belongs to the Special Issue Optical Quantum System)

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12 pages, 11341 KiB

Open AccessArticle

High-Flux Fast Photon-Counting 3D Imaging Based on Empirical Depth Error Correction

by Xiaofang Wang, Tongyi Zhang, Yan Kang, Weiwei Li and Jintao Liang

Photonics 2023, 10(12), 1304; https://doi.org/10.3390/photonics10121304 - 25 Nov 2023

Viewed by 742

Abstract

The time-correlated single-photon-counting (TCSPC) three-dimensional (3D) imaging lidar system has broad application prospects in the field of low-light 3D imaging because of its single-photon detection sensitivity and picoseconds temporal resolution. However, conventional TCSPC systems always limit the echo photon flux to an ultra-low [...] Read more.

The time-correlated single-photon-counting (TCSPC) three-dimensional (3D) imaging lidar system has broad application prospects in the field of low-light 3D imaging because of its single-photon detection sensitivity and picoseconds temporal resolution. However, conventional TCSPC systems always limit the echo photon flux to an ultra-low level to obtain high-accuracy depth images, thus needing to spend amounts of acquisition time to accumulate sufficient photon detection events to form a reliable histogram. When the echo photon flux is increased to medium or even high, the data acquisition time can be shortened, but the photon pile-up effect can seriously distort the photon histogram and cause depth errors. To realize high accuracy TCSPC depth imaging with a shorter acquisition time, we propose a high-flux fast photon-counting 3D imaging method based on empirical depth error correction. First, we derive the photon flux estimation formula and calculate the depth error of our photon-counting lidar under different photon fluxes with experimental data. Then, a function correction model between the depth errors and the number of echo photons is established by numerical fitting. Finally, the function correction model is used to correct depth images at high photon flux with different acquisition times. Experimental results show that the empirical error correction method can shorten the image acquisition time by about one order of magnitude while ensuring a moderate accuracy of the depth image. Full article

(This article belongs to the Special Issue Optical Quantum System)

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12 pages, 528 KiB

Open AccessArticle

Phase-Controlled Absorption and Dispersion Properties of a Multi-Level Quantum Emitter Interacting with Bismuth-Chalcogenide Microparticles

by Theodoros Papachronis, Nikolaos Kyvelos, Emmanuel Paspalakis and Vassilios Yannopapas

Photonics 2023, 10(12), 1296; https://doi.org/10.3390/photonics10121296 - 24 Nov 2023

Viewed by 705

Abstract

We theoretically study the impact of bismuth-chalcogenide microparticles on the linear absorption and dispersion properties of a four-level double-V-type quantum system. The quantum system interacts with two circularly polarized laser fields of the same frequency but with different phases and electric field amplitudes. [...] Read more.

We theoretically study the impact of bismuth-chalcogenide microparticles on the linear absorption and dispersion properties of a four-level double-V-type quantum system. The quantum system interacts with two circularly polarized laser fields of the same frequency but with different phases and electric field amplitudes. Our study indicates that the inclusion of bismuth-chalcogenide microparticles leads to notable alterations in the absorption and dispersion spectra corresponding to one of the probe laser fields (while both fields are present). These alterations are much more dramatic compared to those induced by common plasmonic materials. By manipulating the field amplitudes as well as the phase difference between the two incident waves, the optical properties of the system can be efficiently controlled. Our study also highlights several effects, including complete optical transparency, zero absorption with nonzero dispersion, and gain without inversion. Full article

(This article belongs to the Special Issue Optical Quantum System)

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14 pages, 827 KiB

Open AccessArticle

Spectral Characterization of Two-Photon Interference between Independent Sources

by Lifeng Duan, Aojie Xu and Yun Zhang

Photonics 2023, 10(10), 1125; https://doi.org/10.3390/photonics10101125 - 07 Oct 2023

Cited by 1 | Viewed by 970

Abstract

We present a spectral characterization of two-photon nonclassical interference on a beam splitter (BS) between a weak coherent state source and another source, which emits a phase-randomized weak coherent state, a single-photon state, or a thermal state. Besides spectral characteristics, the average photon [...] Read more.

We present a spectral characterization of two-photon nonclassical interference on a beam splitter (BS) between a weak coherent state source and another source, which emits a phase-randomized weak coherent state, a single-photon state, or a thermal state. Besides spectral characteristics, the average photon number ratio in a given time interval is also considered in our model. The two-photon coincidence probability of two outputs of the BS is numerically calculated with spectral bandwidth ratio and average photon number ratio. Furthermore, the noise of the detection system is taken into account. This also indicates that two-photon interference is able to significantly improve by subtracting two-photon contributions from the input state. All these parameters have a close relation to a real experiment performance and the results may pave new avenues for quantum information technology when two-photon interference between independent sources is necessary. Full article

(This article belongs to the Special Issue Optical Quantum System)

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14 pages, 7388 KiB

Open AccessArticle

Parallel CV-QRNG with Strict Entropy Evaluation

by Zhicang Zheng, Xiaomin Guo, Fading Lin, Yingqi Wang, Yu Wang and Yanqiang Guo

Photonics 2023, 10(7), 786; https://doi.org/10.3390/photonics10070786 - 06 Jul 2023

Cited by 1 | Viewed by 824

Abstract

Continuous-variable quantum random number generators (CV-QRNGs) have promising application prospects thanks to their advantages such as high detection bandwidth, robustness of system, and integratability. In major CV-QRNGs, the generation of random numbers is based on homodyne detection and discretization of the quadrature fluctuations [...] Read more.

Continuous-variable quantum random number generators (CV-QRNGs) have promising application prospects thanks to their advantages such as high detection bandwidth, robustness of system, and integratability. In major CV-QRNGs, the generation of random numbers is based on homodyne detection and discretization of the quadrature fluctuations of the EM fields. Any defectiveness in physical realization may leak information correlated with the generated numbers and the maximal amount of randomness that can be extracted in presence of such side-information is evaluated by the so-called quantum conditional min-entropy. The parallel CV-QRNG overcomes the rate bottleneck of the previous serial type scheme. As a type of device-trusted QRNG, its security needs to be better guaranteed based on self-testing or monitoring that can be rigorously enforced. In this work, four sideband modes of vacuum state within 1.6 GHz detection bandwidth were extracted parallelly as the entropy source, and 16-bit analog-to-digital conversion in each channel was realized. Without making any ideal assumptions, the transfer function of the homodyne and quantization system was measured based on beat method to calibrate the evaluation of the min-entropy. Based on the rigorous entropy evaluation with a hash security parameter of

ε_{h a s h}

= 2⁻¹¹⁰, a real-time generation rate of 7.25 Gbps was finally achieved. Full article

(This article belongs to the Special Issue Optical Quantum System)

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