基于六方氮化硼的确定性量子光源研究进展

量子光源是量子信息科学技术的基石,对于推动光量子科技的进步至关重要。高效、稳定且易于获得的单光子源的实现是促进相关技术发展的关键。目前,六方氮化硼中的单光子源因其高亮度和优异的室温光学稳定性而备受关注。本文概述了六方氮化硼中单光子源的研究现状和物理特性,详细介绍了在六方氮化硼中实现精确定位单光子源的各种制备技术;并探讨了基于六方氮化硼的单光子源在不同应用领域的应用,如与光学微腔和波导的耦合以及通过外部电场或应力对它们的调制。最后,总结了六方氮化硼中单光子源所面临的机遇和挑战,并讨论了目前正在探索的研究方向以及未来的新可能性。

金华市以“会”为媒塑造量子产业生态优势路径研究

量子科技是新一轮科技革命和产业变革的前沿领域,在通信、计算、模拟、传感和安全等领域展现出巨大的潜力。通过阐述“2023国际量子光子学大会”基本情况,分析国际性科技合作盛会落地金华市的重要背景与现实意义,从4个方面提出了金华市将“大会”转化为“大机会”、塑造量子学术和产业生态优势、抢占未来产业发展先机的思路与对策,提供了可借鉴、可复制推广的“金华经验”。

Transport Properties of Two Coupled Quantum Dots Under Optical Pumping

Using the Keldysh-Green function,we present a theoretical study on the electron transport properties of two coupled quantum dots under optical pumping. Plateaus in the I-V curve and resonant peaks in the transmission coefficient occur and can be explained by the local electron density of states in the quantum dots. The effects of the optical pumping frequency and intensity on the transport properties of the system are also discussed. The electron dynamical localization phenomenon occurs when the optical pumping frequency is equal to the discrete hole energy level. This result can be used to realize optical control switches.

New Approach for Solving Master Equations in Quantum Optics and Quantum Statistics by Virtue of Thermo-Entangled State Representation

By introducing a fictitious mode to be a counterpart mode of the system mode under review we introduce the entangled state representation （η｜, which can arrange master equations of density operators p（t） in quantum statistics as state-vector evolution equations due to the elegant properties of （η｜. In this way many master equations （respectively describing damping oscillator, laser, phase sensitive, and phase diffusion processes with different initial density operators） can be concisely solved. Specially, for a damping process characteristic of the decay constant k we find that the matrix element of p（t） at time t in 〈η｜ representation is proportional to that of the initial po in the decayed entangled state （ηe^-kt｜ representation, accompanying with a Gaussian damping factor. Thus we have a new insight about the nature of the dissipative process. We also set up the so-called thermo-entangled state representation of density operators, ρ = f（d^2η/π）（η｜ρ〉D（η）, which is different from all the previous known representations.

Wigner Distribution Function and Husimi Function of a Kind of Squeezed Coherent State

We find a new x-parameter squeezed coherent state （p, q）κ representation, which possesses well-behaved features, i.e., its Wigner function＇s marginal distribution in the ＂q-direction＂ and in the ＂p-direction＂ is the Gauss/an form exp（-κ（q＇ - q）2}, and exp{（p＇ - p）2/κ}, respectively. Based on this, the Husimi function of（p, q）κ is also obtained, which is a Gauss/an broaden version of the Wigner function. The （P, q）κ state provides a good representative space for studying various properties ot the Husimi operator.

Enhancement of Squeezing in Two-Photon Jaynes-Cummings Model with Atomic Measurement

We investigate the squeezing properties of the cavity field in the degenerate two-photon Jaynes Cummings model. Compared with the one-photon Jaynes-Cummings model, the squeezing is more pronounced in the case of two-photon Jaynes-Cummings model under certain conditions.

Interferences in Photodetachment of a Negative Molecular Ion Model

By employing a two-center model, the total and differential cross sections in the photodetachment of ＂a negative molecular ion＂ are studied theoreticedly and obtained for the case of light polarization paredlel to the molecular axis. We find that in contrast to the smooth behavior of the total cross section for perpendicular polarized light, the cross section for parallel polarized light shows an interesting oscillatory structure. The oscillations in the toted cross section may provide a method to determine the distance between the two centers. We explain the oscillation in the toted cross section as an interference effect using closed-orbit theory. We also cedculated the detached-electron flux distributions on a screen placed at a large distance from the negative molecular ion. The distributions display multiple-ring-like interference patterns. Such interference patterns are similar to those in the photodetachment microscopy experiments.

Coherent-Entangled State in Three-Mode and Its Applications

We introduce the new concept of coherent-entangled state （CES）. By virtue of the technique of integration within an ordered product of operators we introduce a new kind of three-mode CES [β,γ,x）, which exhibits both properties of the coherent state and the entangled state. [β,γ,x） makes up a new quantum mechancial representation. Its applications in quantum optics are also presented.

Single Photon Detection of InGaAs/InP APD Based on Gated-mode Operation at Telecom Wavelengths

Based on the commercially available avalanche photodiodes, the basic needs of gated-mode operation for single photon are discussed. Gated-mode technique based on the experimental data for detection of single photon is analyzed at communication wavelengths so that the basic operation parameters can decide properly for efficient detection of single photon. The bias voltage has related to the punch-through voltage in combining the cooling technique with synchronization to decrease the dark counts.

Quantum Tunneling of a Dipolar Bose-Einstein Condensate in Optical Lattice

We study quantum tunneling of a dipolar Bose-Einstein condensate in optical lattice when the spin system initially is prepared in a squeezed coherent state. It is found that there exists quantum tunneling between lattices l and l ＋ 1, l and l - 1, respectively. In particular, when the optical lattice is infinitely long and the spin excitations are in the long-wavelength limit, quantum tunneling disappears between lattices l and l ＋ 1, and that l and l - 1. Correspondingly, the magnetic soliton appears.

A comparison among optical emission spectroscopic methods of determining electron temperature in low pressure argon plasmas

In this article, four kinds of optical emission spectroscopic methods of determining electron temperature are used to investigate the relationship between electron temperature and pressure in the cylindrical plasmas of dc glow discharges at low pressures in laboratory by measuring the relative intensities of ArI lines at various pressures. These methods are developed respectively on the basis of the Fermi-Dirac model, corona model, and two kinds of electron collision cross section models according to the kinetic analysis. Their theoretical bases and the conditions to which they are applicable are reviewed, and their calculation results and fitting errors are compared with each other. The investigation has indicated that the electron temperatures obtained by the four methods become consistent with each other when the pressure increases in the low pressure argon plasmas.

Effects of Electron-Phonon Interaction on Linear and Nonlinear Optical Absorption in Cylindrical Quantum Wires

The electron-phonon interaction influences on lineax and nonfineax optical absorption in cylindrical quantum wires （CQW） with an infinite confining potential axe investigated. The optical absorption coefficients are obtained by using the compact-density-matrix approach and iterative method, and the numerical results are presented for GaAs CQW. The results show that the electron-phonon interaction makes a distinct influence on optical absorption in CQW. The electron-phonon interaction on the wave functions of electron dominates the values of absorption coefficients and the correction of the electron-phonon effect on the energies of the electron makes the absorption peaks blue shift and become wider. Moreover, the electron-phonon interaction influence on optical absorption with an infinite confining potential is different from that with a finite confining potential.

Ultraslow Optical Solitons in a Coupled Double Quantum-Well Nanostructure

We demonstrate the formation of ultraslow dark semiconductor double quantum well （SDQW） structure based optical solitons with a four-level scheme in an asymmetric on intersubband transitions by using only a low-intensity pulsed laser radiation. With appropriate conditions we show numerically that the dark optical soliton can travel with a ultraslow group velocity Vg/c - -10^-3. Such a semiconductor system is much more practical than its atomic counterpart because of its flexible design and the controllable interference strength. This nonlinear optical process in the SDQW solid-state material may be used for the control technology of optical delay lines and optical buffers.

Teleportation of a Superposition of Three Orthogonal States of an Atom via Photon Interference

We propose a scheme to teleport a superposition of three states of an atom trapped in a cavity to a second atom trapped in a remote cavity. The scheme is based on the detection of photons leaking from the cavities after the atom-cavity interaction.

Realization of Bipartite Positive-Operator-Value Measurements of Two-Photon Polarization States

In this letter, we propose a scheme of a special quantum optical Fredkin gate assisted by optical manip- ulations and postselection from the coincidence measurements, and then modify it with cross-Kerr nonlinearities to be suitable for the realization of all possible positive operator-valued measurements of bipartite polarization states. This scheme is feasible in the lab with the current experimental technology.

Allowable Generalized Quantum Gates Using Nonlinear Quantum Optics

In this paper, we give an efficient physical realization of a double-slit duality quantum gate. Weak cross- Kerr nonlinearity is exploited here. The probability of success can reach 1/2. Asymmetrical slit duality control gate also can be constructed conveniently. The special quantum control gate could be realized easily in optical system by our current experimental technology.

Raman Theory for a molecule in a Vibrating Microcavity Oscillating in Fundamental Resonance

We propose a model to describe the energy structure and dynamics of a system of a molecule interacting with infinite photon modes in a vibrating microcavity whose boundary oscillates in the fundamental resonance. By constructing an Lie algebra for the infinite photon modes, we obtain analytical expressions of the energy eigenstates, energy eigenvalues and the system's evolution operator for this Raman model under certain conditions.

Coherent Interband and Intersubband Dynamics in Terahertz-Driven GaAs Quantum Wells

We theoretically investigate the optical absorption spectra and charge density by subjecting a GaAs quantum well to both an intense terahertz (THz)-frequency driving field and an optical pulse within the theory of density matrix. In presence of a strong THz field, the optical transitions in quantum well subbands are altered by the THz field. The alteration has a direct impact on the optical absorption and the charge density. The excitonic peak splitting and THz optical sideband in the absorption spectra show up when changing the THz field intensity and/or frequency. The Autler-Towns splitting is a result from the THz nonlinear dynamics of confined excitons. On the other hand, the carrier charge density is created as wave packets formed by coherent superposition of several eigenstates. The charge density exhibitsquantum beats for short pulses and/or wider wells and is modulated by the THz field.

Scheme for Implementation of Optimal Cloning of Arbitrary Single Particle Atomic State into Two Photonic States

We present a feasible scheme to implement the 1→2 optimal cloning of arbitrary single particle atomic state into two photonic states, which is important for applications in long distance quantum communication. Our scheme also realizes the tele-NOT gate of one atom to the distant atom trapped in another cavity. The scheme is based on the adiabatic passage and the polarization measurement. It is robust against a number of practical noises such as the violation of the Lamb Dicke condition, spontaneous emission, and detection inefficiency.

Anticontrol of Quantum Chaos in Hamiltonian Systems

We present a method of realizing anticontrol chaos in a quantum confined system consisting of N two-levelatoms within a cavity, using a time-delayed optic field. The delay time plays a construction and organization role forproducing temporal chaos, while the interaction between atoms and photons creates spatial chaos. The chaos is quitesensitive to small time delayed. The spectral decomposition of the Hamiltonian obtained by using projection methodologyreveals that evolution of the left eigenvectors shows quite complicated chaotic fashions. The method we proposed maybe easily tested in experiment, and provides a general method using a sort of driving optic field to achieve anticontrol ofchaos for quantum systems.