Guangjiong dong - Academia.edu (original) (raw)

Papers by Guangjiong dong

Physical review, Jul 18, 2022

Frontiers of Physics, 2011

We present a tutorial review on the topics related to current development in cavity optomechanics... more We present a tutorial review on the topics related to current development in cavity optomechanics, with special emphasis on cavity optomechanical effects with ultracold gases, Bose-Einstein condensates, and spinor Bose-Einstein condensates. Topics including the quantum model and nonlinearity of the cavity optomechanics, the principles of optomechanical cooling, radiation-pressure-induced nonlinear states, the chaotic dynamics in a condensate-mirror-hybrid optomechanical setup, and the spin-mixing dynamics controlled by optical cavities are covered.

Optics Communications, Jul 1, 1996

Abstract A soliton with a nonvanishing boundary condition is found for the generalized nonlinear ... more Abstract A soliton with a nonvanishing boundary condition is found for the generalized nonlinear Schrodinger equation under the condition β 2 β 3 = ω 0 2 ( β 2 is the second order dispersion, β 3 is the third order dispersion, ω 0 is the carrier frequency) neglecting the terms concerned with loss and retarded nonlinear response. In the normal dispersion regime, dark solitons exist, however in the anomalous dispersion regime, bright solitons exist superimposed on the continuous wave background, and especially in the long wave limit rational solitons also exist.

New Journal of Physics

Spin-orbital coupling (SOC) and parity-time ($\\mathcal{PT}$) symmetry both have attracted paramo... more Spin-orbital coupling (SOC) and parity-time ($\\mathcal{PT}$) symmetry both have attracted paramount research interest in condensed matter physics, cold atom physics, optics and acoustics to develop spintronics, quantum computation, precise sensors and novel functionalities. Natural SOC is an intrinsic relativistic effect. However, there is an increasing interest in synthesized SOC nowadays. Here, we show that in a mathcalPT\\mathcal{PT}mathcalPT-symmetric pseudo spin-1/2 system (in other words, two-state system), the momentum-dependent balanced gain and loss can synthesize a new type of SOC, which we call imaginary SOC. The imaginary SOC can substantially change the energy spectrum of the system. Firstly, we show that it can generate a pure real energy spectrum with a double-valleys structure. Therefore, it has the ability to generate supersolid stripe states. Especially, the imaginary SOC stripe state can have a high contrast of one. Moreover, the imaginary SOC can also generate a spectrum with tun...

Journal of the Optical Society of America B, 2020

Laser cooling of macroscopic matters could pave the way for studying quantum-classic crossover an... more Laser cooling of macroscopic matters could pave the way for studying quantum-classic crossover and macroscopic quantum mechanics with potential application in quantum technologies. In this paper, we propose polarization gradient cooling and trapping of the microsphere in free space by exciting the degenerate whispering gallery modes using two counterpropagating optical fields with different polarizations. Cooling temperature is related to the internal temperature fluctuation and collision with residual air molecules as well as laser shot noise. Cooling and trapping of the microsphere are controlled by optical polarization of the optical waves. Orthogonal polarization cooling, compared with nonorthogonal polarization cooling, has higher cooling efficiency and is free from thermo-refractive and -elastic noises and thus has lower temperature. Simultaneous cooling and optical trapping of the microsphere could be achieved with the two nonorthogonally polarized optical fields. Our numerical simulation shows that a cooling temperature of less than 1 mK in a high vacuum environment could be achieved. Finally, influence of the electric affinity of a charged microsphere on optical forces has been investigated. The current scheme is for 1D cooling and trapping, but it could be extended to the 3D case.

Physical Review Letters, 2013

It is shown that a single-layer array of high electric permittivity (high-ε) rods with radius sma... more It is shown that a single-layer array of high electric permittivity (high-ε) rods with radius smaller than λ/10 is capable of reflecting more than 97% of the energy of optical waves with arbitrary incident angle. Here λ is the incident wavelength. The occurrence of the phenomenon depends on the construction of two particular grating modes (GMs) in the array which result in two corresponding transmitted wave components that cancel each other. The construction of the dominant GMs in the array benefits from the highly independent manipulability of the angular momenta components with opposite signs in high-ε particles. The effect offers a possibility for improving the optical elements integration level in the on-chip optical circuits.

Physical Review A, 2012

We study the quantum nonequilibrium dynamics of ultracold three-level atoms trapped in an optical... more We study the quantum nonequilibrium dynamics of ultracold three-level atoms trapped in an optical lattice, which are excited to their Rydberg states via a two-photon excitation with nonnegligible spontaneous emission. Rich quantum phases including uniform phase, antiferromagnetic phase and oscillatory phase are identified. We map out the phase diagram and find these phases can be controlled by adjusting the ratio of intensity of the pump light to the control light, and that of two-photon detuning to the Rydberg interaction strength. When the two-photon detuning is blue-shifted and the latter ratio is less than 1, bistability exists among the phases. Actually, this ratio controls the Rydberg-blockade and antiblockade effect, thus the phase transition in this system can be considered as a possible approach to study both effects.

Physical Review A, 2007

... Rev. A 72, 033614 (2005); MI Rodas-Verde, Humberto Michinel, and VM Perez-Garcia, Phys. Rev. ... more ... Rev. A 72, 033614 (2005); MI Rodas-Verde, Humberto Michinel, and VM Perez-Garcia, Phys. Rev. Lett. 95, 153903 (2005); Fatkhulla Kh. ... Rev. Lett. 73, 1368 (1994) [SPIN];[INSPEC];[CAS];[ MEDLINE]. D. Pelinovsky, J. Sears, L. Brzozowaski, and EH Sargent, J. Opt. Soc. Am. ...

Faraday Discussions, 2009

We present an investigation of the dynamics of centre-of-mass of a neutral particle cloud in a ca... more We present an investigation of the dynamics of centre-of-mass of a neutral particle cloud in a cavity pumped by an optical field. We derive an expression for the pump threshold for spatial self-organization of the particles and analyze its scaling laws in terms of the system parameters. Using a newly developed statistical model, we simulate the dynamics of the particles and numerically obtain the scaling laws. We show good agreement between the analytic formulae and simulations. We further use the scaling relation to discuss the operating conditions for cavity cooling a large ensemble of particles. Finally, we study cavity cooling of an ensemble of molecules with an initial temperature of around 10 mK. We show that 35% of the molecules are trapped by the optical field intensity in the cavity and a final temperature below 1 mK is reached.

Chinese Science Bulletin, 2012

We review our recent experimental progress in quantum technology employing amplification effect o... more We review our recent experimental progress in quantum technology employing amplification effect of four-wave mixing in a rubidium vapor. We have produced an intensity difference squeezed light source at frequencies as low as 1.5 kHz which is so far the lowest frequency at which squeezing has been observed in an atomic system. Moreover, we find that the bandwidth of our squeezed light source can be controlled with light intensity pumping. Using our non-classical light source, we have further developed a nonlinear Mach-Zehnder (MZ) interferometer, for which the maximum fringe intensity depends quadratically on the intensity of the phase-sensing field at the high-gain regime, leading to much better sensitivity than a linear MZ interferometer in which the beam splitters have the same phase-sensing intensity. The quantum technologies developed by our group could have great potential in areas such as precision measurement and quantum information.

Physical Review A, 2008

We propose a model of a nonlinear double-well potential (NDWP), alias a double-well pseudopotenti... more We propose a model of a nonlinear double-well potential (NDWP), alias a double-well pseudopotential, with the objective to study an alternative implementation of the spontaneous symmetry breaking (SSB) in Bose-Einstein condensates (BECs) and optical media, under the action of a potential with two symmetric minima. In the limit case when the NDWP structure is induced by the local nonlinearity coefficient represented by a set of two delta-functions, a fully analytical solution is obtained for symmetric, antisymmetric and asymmetric states. In this solvable model, the SSB bifurcation has a fully subcritical character. Numerical analysis, based on both direct simulations and computation of stability eigenvalues, demonstrates that, while the symmetric states are stable up to the SSB bifurcation point, both symmetric and emerging asymmetric states, as well as all antisymmetric ones, are unstable in the model with the delta-functions. In the general model with a finite width of the nonlinear-potential wells, the asymmetric states quickly become stable, simultaneously with the switch of the SSB bifurcation from the subcritical to supercritical type. Antisymmetric solutions may also get stabilized in the NDWP structure of the general type, which gives rise to a bistability between them and asymmetric states. The symmetric states require a finite norm for their existence, an explanation to which is given. A full diagram for the existence and stability of the trapped states in the model is produced. Experimental observation of the predicted effects should be possible in BEC formed by several hundred atoms.

Quantum systems are inherently dissipation-less, making them excellent candidates even for classi... more Quantum systems are inherently dissipation-less, making them excellent candidates even for classical information processing. We propose to use an array of large-spin quantum magnets for realizing a device which has two modes of operation: memory and data-bus. While the weakly interacting low-energy levels are used as memory to store classical information (bits), the high-energy levels strongly interact with neighboring magnets and mediate the spatial movement of information through quantum dynamics. Despite the fact that memory and data-bus require different features, which are usually prerogative of different physical systems -- well isolation for the memory cells, and strong interactions for the transmission -- our proposal avoids the notorious complexity of hybrid structures. The proposed mechanism can be realized with different setups. We specifically show that molecular magnets, as the most promising technology, can implement hundreds of operations within their coherence time, ...

Cooling a range of molecules to ultracold temperatures (<1 mK) is a difficult but important ch... more Cooling a range of molecules to ultracold temperatures (<1 mK) is a difficult but important challenge in molecular physics and chemistry. Collective cavity cooling of molecules is a promising method that does not rely on molecular energy level and thus can be applied to all molecules in principle. However, the initial lack of cold molecules leads to the difficulty in its experimental implementation. We show that efficient collective sympathetic cooling of molecules to sub-mK temperatures using a large ensemble of atoms within a cavity is feasible. This approach is a new type of sympathetic cooling which does not rely on direct collisions between atoms and molecules, but utilizes thermalization via their mutual interaction with a cavity field. Two important mechanisms are identified. This include: (1) giant enhancement of cavity optical field from the efficient scattering of the pump light by the atoms; (2) cavity-mediated collective interaction between the atoms and the molecules...

Self-accelerating waves in conservative systems, which usually feature slowly decaying tails, suc... more Self-accelerating waves in conservative systems, which usually feature slowly decaying tails, such as Airy waves, have drawn great interest in studies of quantum and classical wave dynamics. They typically appear in linear media, while nonlinearities tend to deform and eventually destroy them. We demonstrate, by means of analytical and numerical methods, the existence of robust oneand two-dimensional (1D and 2D) self-accelerating tailless solitons and solitary vortices in a model of twocomponent Bose-Einstein condensates, dressed by a microwave (MW) field, whose magnetic component mediates long-range interaction between the matter-wave constituents, with the feedback of the matter waves on the MW field taken into account. In particular, self-accelerating 2D solitons may move along a curved trajectory in the coordinate plane. The system may also include the spin-orbit coupling between the components, leading to similar results for the self-acceleration. The effect persists if the con...

Electron magnetic circular dichroism (EMCD) can detect the magnetic properties of materials at th... more Electron magnetic circular dichroism (EMCD) can detect the magnetic properties of materials at the nanoscale, but its wide applications are limited by stringent specimen orientation and noisy signal outputs. To overcome these challenges, electron vortex beams (EVBs) were most recently proposed to develop chirality-dependent EMCD (CEMCD), yet convincing and reproducible CEMCD has not yet been demonstrated. In electron energy-loss spectroscopy (EELS) experiments of EMCD, electron-atom scattering has played a core role. Here, from a model research on the scattering of EVBs by a single atom in a magnetic field, we show a way of generating chirality-dependent scattering which is of potential application to CEMCD. The mechanism is to break the symmetry of the joint occupation probability amplitudes for two scattering channels with opposite magnetic quantum number differences (m j), respectively, for two EVBs with opposite topological charges (l). Particularly, the Zeeman effect and spin-orbit coupling jointly can lead to this chirality-dependent scattering, signaled as the chirality-dependent differential cross section (DCS) for the EVB. The DCS can be optimized by choosing the magnetic field strength and topological charge for getting the strongest EMCD. Due to angular momentum conservation, l = m j is the optimum topological charge, which could be useful for the selective probe of an internal state. We show that using EVB with a narrow width can relax the requirement of precise controlling of the opening angle and improve the spatial resolution. Finally, we show that chirality-dependent scattering strength decreases with increasing of the impact parameter.

We propose a model including a one-dimensional harmonic chain of oscillators whose two ends coupl... more We propose a model including a one-dimensional harmonic chain of oscillators whose two ends coupled two cavity-optomechanical systems for studying one-dimensional thermal conductivity in statistical physics. In this model, the cavity-optomechanical systems function as two laser-engineerable thermal reservoirs. When the effective temperatures of the two reservoirs are not equal, a heat flux through the chain can be generated, and moreover the classical and quantum features of the heat flux have been studied. We further show that the heat flux does not obey the Fourier's law in this model. The thermal switching phenomenon could be induced by controlling the on-site vibrational frequency. Finally, we propose to apply the correlation between two mechanical oscillators to measure the heat flux through the chain.