- 标题
- 摘要
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- 实验方案
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Efficient excitation of dye molecules for single photon generation
摘要： A reliable single photon source is required for many aspects of quantum technology. Organic molecules are attractive for this application because they can have high quantum yield and can be photostable, even at room temperature. To generate a photon with high probability, a laser must excite the molecule efficiently. We develop a simple model for that efficiency and discuss how to optimise it. We demonstrate the validity of our model through experiments on a single dibenzoterrylene (DBT) molecule in an anthracene crystal. We show that the excitation probability cannot exceed 75% at room temperature, but can increase to over 99% if the sample is cooled to liquid nitrogen temperature. The possibility of high photon generation efficiency with only modest cooling is a significant step towards a reliable photon source that is simple and practical.
关键词： single molecules,photon anti-bunching,single photon source,quantum optics,confocal microscopy
更新于2025-09-09 09:28:46
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Generation of sustained optimal entropy squeezing of a two-level atom via non-Hermitian operation
摘要： We investigate the entropy squeezing of a two-level atom in the Jaynes–Cummings model, and provide a scheme to generate the sustained optimal entropy squeezing of the atom via non-Hermitian operation. Our results show that the squeezing degree and the persistence time of entropy squeezing of atomic polarization components greatly depend on the non-Hermiticity intensity in non-Hermitian operation. Especially, under a proper choice of non-Hermiticity parameters, the sustained optimal entropy squeezing of the atom can be generated even though the atom is initially prepared in a no entropy squeezing state.
关键词： Jaynes–Cummings model,entropy squeezing,non-Hermitian dynamics,quantum optics
更新于2025-09-09 09:28:46
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X-ray photon pairs with highly suppressed background
摘要： We describe an experiment demonstrating the possibility to generate collinear indistinguishable x-ray photon pairs with a highly suppressed background. By choosing angles near 90 degrees between the detectors and the pump beam, where the pump polarization is in the scattering plane, we improve the signal-to-noise ratio by 2 orders of magnitude. We measure the pure coincidence spectrum without any energy discrimination with a bandwidth of 1.5 keV at the full width at half maximum.
关键词： background suppression,parametric down conversion,quantum optics,signal-to-noise ratio,x-ray photon pairs
更新于2025-09-09 09:28:46
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Radiation damage free ghost diffraction with atomic resolution
摘要： The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghost diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several ?ngstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.
关键词： atomic resolution,x-ray quantum optics,diffraction imaging
更新于2025-09-09 09:28:46
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Optomechanically induced transparency under the influence of spin ensemble system
摘要： Optomechanics is a growing research field, which has received a great attention in the last decade both theoretically and experimentally. In this paper, we theoretically study the opto-mechanically induced transparency with spins coupled to the cavity field, while the cavity filed is driven by external strong coupling and weak probe fields. We analytically calculated the dynamics, as well as the transmissivity of the optomechanical system. The transmission is also examined and discussed. Moreover, the detailed behavior of the transmission shows well the optomechanical induced transparency (OMIT). The paper also show that the OMIT behaviors are strongly affected by the coupling between the spin ensemble and cavity field, as well as the spin decay rate.
关键词： Quantum optics,Optics,Quantum optomechanics
更新于2025-09-04 15:30:14
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Quantum imaging with sub-Poissonian light: challenges and perspectives in optical metrology
摘要： Non-classical correlations in optical beams offer the unprecedented opportunity of surpassing conventional limits of sensitivity and resolution in optical measurements and imaging, especially but not only, when a low photon flux down/single photons are measured. We review the principles of quantum imaging and sensing techniques which exploit sub-Poissonian photon statistics and non-classical photon number correlation, presenting some state-of-the-art achievements in the field. These quantum photonics protocols have the potential to trigger major steps in many applications, such as microscopy and biophotonics and represent an important opportunity for a new deal in radiometry and photometry.
关键词： quantum optics,quantum correlation,sub-Poissonian light,Quantum enhanced measurement
更新于2025-09-04 15:30:14
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Two-photon self-Kerr nonlinearities for quantum computing and quantum optics
摘要： The self-Kerr interaction is an optical nonlinearity that produces a phase shift proportional to the square of the number of photons in the field. At present, many proposals use nonlinearities to generate photon-photon interactions. For propagating fields these interactions result in undesirable features such as spectral correlation between the photons. Here we engineer a discrete network composed of cross-Kerr interaction regions to simulate a self-Kerr medium. The medium has effective long-range interactions implemented in a physically local way. We compute the one- and two-photon S matrices for fields propagating in this medium. From these scattering matrices we show that our proposal leads to a high-fidelity photon-photon gate. In the limit where the number of nodes in the network tends to infinity, the medium approximates a perfect self-Kerr interaction in the one- and two-photon regime.
关键词： quantum computing,quantum optics,photon-photon gate,cross-Kerr interaction,self-Kerr interaction
更新于2025-09-04 15:30:14
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Photon Noise Suppression by a Built-in Feedback Loop
摘要： Visionary quantum photonic networks need transform-limited single photons on demand. Resonance fluorescence on a quantum dot provides the access to a solid-state single photon source, where the environment is unfortunately the source of spin and charge noise that leads to fluctuations of the emission frequency and destroys the needed indistinguishability. We demonstrate a built-in stabilization approach for the photon stream, which relies solely on charge carrier dynamics of a two-dimensional hole gas inside a micropillar structure. The hole gas is fed by hole tunneling from field-ionized excitons and influences the energetic position of the excitonic transition by changing the local electric field at the position of the quantum dot. The standard deviation of the photon noise is suppressed by nearly 50% (noise power reduction of 6 dB) and it works in the developed micropillar structure for frequencies up to 1 kHz. This built-in feedback loop represents an easy way for photon noise suppression in large arrays of single photon emitters and promises to reach higher bandwidth by device optimization.
关键词： semiconductor heterostructure,single photon source,two-dimensional hole gas,Quantum dots,quantum optics,resonance fluorescence
更新于2025-09-04 15:30:14
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Quadrature squeezing of the mechanical mode in a superconducting electromechanical system
摘要： We propose a scheme for realizing quadrature squeezing of the mechanical mode in a superconducting electromechanical system, where a nanomechanical resonator (NAMR) is coupled to a superconducting transmission line resonator (STLR) via a superconducting quantum interference device (SQUID), and the SQUID acts as a qubit. Under a large detuning condition, we use the Fr?hlich-Nakajima transformation to adiabatically eliminate the qubit and obtain an effective Hamiltonian for the STLR and the NAMR. Our results show that a strong squeezing effect (beyond 3 dB limit) can occur in the NAMR, and the squeezing degree can be optimized by controlling the strength of the driving field and the dissipation ratio of the system. One of the most notable features of our results is the universality, i.e. the results only depend on a few scaled quantities, not on too many parameters.
关键词： squeezed states,quantum electrodynamics,quantum optics,coupled resonators
更新于2025-09-04 15:30:14