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Linear and nonlinear optical effects in biophotonic structures using classical and nonclassical light
摘要： In this perspective article, we review the optical study of different biophotonic geometries and biological structures using classical and nonlinear regime, especially highlighting the link between these morphologies and modern biomedical research. Additionally, the importance of nonlinear optical study in biological research, beyond traditional cell imaging is also highlighted and described. Finally, we present a short introduction regarding nonclassical light and describe the new future perspective of quantum optical study in biology, revealing the link between quantum realm and biological research.
关键词： linear and nonlinear spectroscopy,nonclassical light,squeezed light,optics,ghost imaging,biophotonics,fluorescence spectroscopy
更新于2025-09-23 15:21:01
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Continuous-wave 6-dB-squeezed light with 2.5-THz-bandwidth from single-mode PPLN waveguide
摘要： Terahertz (THz)-bandwidth continuous-wave (CW) squeezed light is essential for integrating quantum processors with time-domain multiplexing (TDM) by using optical delay line interferometers. Here, we utilize a single-pass optical parametric amplifier (OPA) based on a single-spatial-mode periodically poled ZnO:LiNbO3 waveguide, which is directly bonded onto a LiTaO3 substrate. The single-pass OPA allows THz bandwidth, and the absence of higher-order spatial modes in the single-spatial-mode structure helps avoid degradation of squeezing. In addition, the directly bonded ZnO-doped waveguide has durability for high-power pump and shows small photorefractive damage. Using this waveguide, we observe CW 6.3-dB squeezing at 20-MHz sideband by balanced homodyne detection. This is the first realization of CW squeezing with a single-pass OPA at a level exceeding 4.5 dB, which is required for the generation of a two-dimensional cluster state. Furthermore, the squeezed light shows 2.5-THz spectral bandwidth. The squeezed light will lead to the development of a high-speed on-chip quantum processor using TDM with a centimeter-order optical delay line.
关键词： terahertz-bandwidth,quantum information processing,squeezed light,continuous-wave,single-mode PPLN waveguide
更新于2025-09-19 17:13:59
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4-dB Quadrature Squeezing With Fiber-Coupled PPLN Ridge Waveguide Module
摘要： We have developed an optical parametric amplification module for quadrature squeezing with input and output ports coupled with optical fibers for both fundamental and second harmonic. The module consists of a periodically poled LiNbO3 ridge waveguide fabricated with dry etching, dichroic beamsplitters, lenses and four optical fiber pigtales. The high durability of the waveguide and the good separation of squeezed light from a pump beam by the dichroic beamsplitter enable us to inject intense continuous-wave pump light with the power of over 300 mW. We perform ?4.0±0.1 dB of noise reduction for a vacuum state at 1553.3 nm by using a fiber-optics-based measurement setup, which consists of a fiber-optic beamsplitter and a homemade fiber-receptacle balanced detector. The intrinsic loss of the squeezed vacuum in the module is estimated to be 25%. Excluding the extrinsic loss of the measuremental system, the squeezing level in the output fiber of the module is estimated to be ?5.7±0.1 dB. A modularized alignment-free fiber-coupled quadrature squeezer could help to realize quantum information processing with fiber optics.
关键词： PPLN waveguide,fiber optics,squeezed light
更新于2025-09-19 17:13:59
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Quantum Squeezing of the Field of a Single-Atom Laser under Conditions of a Variable Coupling Constant
摘要： A nonstationary regime of squeezed-light generation by a single-atom laser is investigated. Dependences of the quantum-squeezing parameter and radiation intensity on modulation frequency of the atom–field coupling constant are obtained. It is demonstrated that a resonance appears at the modulation frequency equal to twice the average coupling constant, which leads to a more efficient quantum squeezing in a nonstationary harmonic regime than in the case of a stationary regime for the same values of the relaxation and pump parameters.
关键词： single-atom laser,coupling constant,squeezed light
更新于2025-09-19 17:13:59
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Approximating vibronic spectroscopy with imperfect quantum optics
摘要： We study the impact of experimental imperfections on a recently proposed protocol for performing quantum simulations of vibronic spectroscopy. Specifically, we propose a method for quantifying the impact of these imperfections, optimizing an experiment to account for them, and benchmarking the results against a classical simulation method. We illustrate our findings using a proof of principle experimental simulation of part of the vibronic spectrum of tropolone. Our findings will inform the design of future experiments aiming to simulate the spectra of large molecules beyond the reach of current classical computers.
关键词： quantum optics,boson sampling,squeezed light,quantum simulation,vibronic spectroscopy,quantum chemistry
更新于2025-09-10 09:29:36
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Excess Loss in Homodyne Detection Originating from Distributed Photocarrier Generation in Photodiodes
摘要： The distributed absorption of photons in photodiodes induces an excess noise in continuous-wave photodetection above the transit-time roll-off frequency. We show that it can be treated as a frequency-dependent excess optical loss in homodyne detection. This places a limit on the bandwidth of high-accuracy homodyne detection, even if an ideal photodetector circuit is available. We experimentally evaluate the excess loss in two ways: a comparison of signal gain and shot-noise gain of one-port homodyne detection and a balanced homodyne detection of squeezed light at a 500-MHz sideband. These results agree with an analytic expression we develop, where the randomness of the photoabsorption is directly modeled by an intrusion of vacuum field. At 500 MHz, we estimate the excess loss at 14% for a Si photodiode with 860-nm incident light, while the numerical simulation predicts much smaller excess loss in (In, Ga)As photodiodes with 1550 nm light.
关键词： squeezed light,photodiodes,excess noise,homodyne detection,quantum measurement
更新于2025-09-09 09:28:46