Nai-Hang Kwong

Collective terahertz fluctuation modes in a polariton laser

arXiv (Cornell University), Feb 2, 2023

Metamorphosis of Goldstone and soft fluctuation modes in polariton lasers

Physical Review B

For a driven-dissipative quantum many-body system prepared in a spontaneous broken-symmetry stead... more For a driven-dissipative quantum many-body system prepared in a spontaneous broken-symmetry steady state, in addition to the Goldstone mode the soft fluctuation modes provide important insight into the system's dynamics. Using a microscopic polariton laser theory, we find a rich transformation behavior of discrete and continuum soft modes in a two parameter (pump density and cavity dissipation rate) space. In addition to finding exceptional-point Goldstone companion modes, our theory yields a unified picture of a variety of seemingly disconnected physical concepts including Mott transition, Mollow spectra or relaxation oscillations, and polaritonic Bardeen-Cooper-Schrieffer gaps.

Download

Double γ decay in 40 Ca and 90 Zr

On a Response Function and Two-Body Density Matrix of Nuclear Matter

HNPS Proceedings, 2020

We present a summary of on-going calculations that address the static and dynamic structure of nu... more We present a summary of on-going calculations that address the static and dynamic structure of nuclear matter. Specific projects include (i) evaluation of the density-density response function and corresponding dynamic structure factor, based on the correlated random-phase approximation (CRPA_I) and generalizations of this method, and (ii) low-order variational calculation of the reduced two-body density matrix and corresponding generalized momentum distribution. The numerical applications involve the model interaction V2.

Download

The energy dependence of nuclear reaction cross sections

Physics Letters B, 1984

... of anp satlutelzaa -un aui aze sanlen paleina[sa aul ut szeq zozza auZ -1iam Xiqeuoseaz aazRu... more

Theory of optical refrigeration in p-doped semiconductors

2007 Quantum Electronics and Laser Science Conference, 2007

ABSTRACT We present a microscopic theory for luminescence of doped GaAs and its application to a ... more

A Tale of Two Systems: Resonator Structures and Coupled Quantum Wells

Frontiers in Optics, 2005

ABSTRACT

Polariton amplification in a multiple-quantum-well resonant photonic crystal

Based on a microscopic many-particle theory we study the amplification of polaritons in a multipl... more Based on a microscopic many-particle theory we study the amplification of polaritons in a multiple-quantum-well resonant photonic crystal. For the Bragg-spaced multiple quantum wells under investigation we predict that in a typical pump-probe setup four-wave mixing processes can lead to an unstable energy transfer from the pump into the probe and the background-free four-wave mixing directions. We find that under certain excitation conditions this phase-conjugate oscillation induced instability can lead to a large amplification of the weak probe pulse.

Download

Theory of optical gain from four-wave mixing instabilities in quantum wells

2007 Quantum Electronics and Laser Science Conference, 2007

ABSTRACT We predict that in a typical pump-probe setup four-wave mixing instabilities associated ... more

Theory of ultrafast optical gain in the nonlinear reflectivity of semiconductor Bragg structures

2006 Conference on Lasers and Electro-Optics and 2006 Quantum Electronics and Laser Science Conference, 2006

We present a microscopic theory for the nonlinear reflection of semiconductor Bragg structures. O... more

Polarization-Dependence of Ultrafast Optical Nonlinearities of Bragg-Spaced Quantum Wells

2007 Conference on Lasers and Electro-Optics (CLEO), 2007

We present a microscopic theory for the polarization dependence of the nonlinear reflection of Br... more

Evidence of nonperturbative exciton-exciton scattering in four-wave-mixing signals in quantum well microcavities

Summary form only given. The role of exciton-exciton scattering in the nonlinear optical response... more Summary form only given. The role of exciton-exciton scattering in the nonlinear optical response of semiconductor quantum wells is well established. However, an interesting question arising from the system's dimensionality has so far not been addressed. In the quantum theory of scattering in two dimensions, the scattering amplitude behaves non-smoothly and non-perturbatively at low energies. While the exact scattering amplitude vanishes as 1/ln (energy) as energy ↓0, the second Born approximation diverges logarithmically. These properties result from the system's dimensionality and hold for any short-range well-behaved potential. One may ask whether the second Born approximation also fails for exciton-exciton scattering in two-dimensional structures and how this breakdown may be experimentally detected. In this contribution, we address this question within a microscopic theory of frequency-degenerate four-wave-mixing signals from a quantum-well microcavity. Analyzing an e...

Random walk analysis of quantum chaos

Physics Letters A, 1985

... Volume 107A, number 4 PHYSICS LETTERS 28 January 1985 RANDOM WALK ANALYSIS OF QUANTUM CHAOS E... more ... Volume 107A, number 4 PHYSICS LETTERS 28 January 1985 RANDOM WALK ANALYSIS OF QUANTUM CHAOS EG LANZA 1, NH KWONG 2 and RH IBARRA 3 MaxPlanckInstitutfr Kemphysik ... T Rm(t) = Re T fl Am (t&#x27;)Am(t&#x27; + t) dt&#x27; 0 T 2 T j Am(t) dt&#x27;) 0 TX (T f JAm(tl )J2 dt&#x27; 0 ITT 1 ...

Distortionless light pulse delay in quantum-well Bragg structures

Optics Letters, 2005

We describe a reflection scheme that allows Bragg-spaced semiconductor quantum wells to be used t... more We describe a reflection scheme that allows Bragg-spaced semiconductor quantum wells to be used to trap, store, and release light. We study the temporal and spectral distortion of delayed light pulses and show that this geometry allows multibit delays and offers a high degree of distortion compensation.

Download

A Fortran code for solving the Kadanoff–Baym equations for a homogeneous fermion system

Computer Physics Communications, 1999

Abstract A Fortran code for solving the KadanoffBaym equations for a homogeneous fermion system ... more

Control of transverse optical patterns in semiconductor quantum well microcavities

Control of transverse optical patterns in semiconductor quantum well microcavities 1 M.H. LUK, Y.C.

Download

A low-dimensional population-competition model for analyzing transverse optical patterns

Under favorable conditions, laser beams passing through a nonlinear medium (e.g. atomic vapors) c... more Under favorable conditions, laser beams passing through a nonlinear medium (e.g. atomic vapors) can undergo directional instabilities, generating transverse optical patterns in the far field. In particular, a low intensity all-optical switching scheme using these transverse patterns in semiconductor quantum well microcavities was numerically demonstrated. Trying to understand the switching mechanism through the simulation results has turned out to be a complicated task. In this Contribution, we present a low-dimensional "population-competition' model that (i) exhibits nearly all the pattern selection and switching behaviors and (ii) is simple enough to allow a comprehensive analysis of its solution structure in the relevant region of parameter space. We will explain the relation between this simple model and the realistic theory. Using elementary methods in Catastrophe Theory, we analyze the "phase diagrams" of our model's steady state solutions in parameter space, with the help of which we construct an organized picture of the behaviors of the realistic simulation results.

Download

Theory of optically controlled anisotropic polariton transport in semiconductor double microcavities

Journal of the Optical Society of America B, 2017

Exciton polaritons in semiconductor microcavities exhibit many fundamental physical effects, with... more Exciton polaritons in semiconductor microcavities exhibit many fundamental physical effects, with some of them amenable to being controlled by external fields. The polariton transport is affected by the polaritonic spin-orbit interaction, which is caused by the splitting of transverseelectric and transverse-magnetic (TE-TM) modes. This is the basis for a polaritonic Hall effect, called optical spin Hall effect (OSHE), which is related to the formation of spin/polarization textures in momentum space, determining anisotropic ballistic transport, as well as related textures in real space. Owing to Coulombic interactions between the excitonic components of the polaritons, optical excitation of polaritons can affect the OSHE. We present a theoretical analysis of the OSHE and its optical control in semiconductor double microcavities, i.e. two optically coupled cavities, which are particularly well suited for the creation of polaritonic reservoirs that affect the spin-texture-forming polaritons. The theory is formulated in terms of a set of double-cavity spinorpolariton Gross-Pitaevskii equations. Numerical solutions feature, among other things, a controlled rotation of the spin texture in momentum space. The theory also allows for an identification of the effective magnetic field component that determines the optical control in phenomenological pseudo-spin models in terms of exciton interactions and the polariton density in the second lower polariton branch.

Download

Comparison of the collision delay and displacements within realistic potentials

We calculate the nonlocal shifts required in the extended Boltzmann (BUU) equation for different ... more We calculate the nonlocal shifts required in the extended Boltzmann (BUU) equation for different realistic potentials. The nonlocal shifts are interpreted in terms of the kinetic scattering events. Since the nonlocal shifts are given by off-shell derivatives of the scattering T-matrix we are able to compare the slight off-shell behavior of the different potentials by this way. While the Bonn one-Boson-exchange (A-C) and Paris potentials yield very close results, the separable Paris potential is found to provide different values from the others

Effects of intervalence band coherences on the coherently coupled heavy-hole–light-hole Stark shift in semiconductor quantum wells

Physical Review B, 2002

A theoretical study of the coherently coupled heavy-hole-light-hole optical Stark effect in semic... more A theoretical study of the coherently coupled heavy-hole-light-hole optical Stark effect in semiconductor quantum wells is presented. Based on a detailed investigation of the various many-body contributions to the Stark shifts, we identify a parameter regime in which the existence of intervalence band coherences ͑analogous to the nonradiative Raman coherence in three-level atoms͒ can be inferred from the coherently coupled heavy-hole-light-hole excitonic optical Stark shift. The analysis is performed for the third-order nonlinear optical regime ( 3 regime͒, and is based on the dynamics-controlled truncation ͑DCT͒ formalism. It includes the relevant optical selection rules, excitonic and two-exciton-correlation ͑e.g., biexcitonic͒ effects.

Download

Uploads

Papers by Nai-Hang Kwong

Log In