Raymond Ooi | University of Malaya, Malaysia (original) (raw)

Papers by Raymond Ooi

Applied Physics B, 2013

We study the propagation and second harmonic generation of ultrashort pulse in nonlinear photonic... more We study the propagation and second harmonic generation of ultrashort pulse in nonlinear photonic crystal using a combination of Fourier transform and transfer matrix method. The focus is on the reflected and transmitted output of fundamental pump pulse and second harmonic pulse in frequency and time domains, the temperature dependence of the reflection and transmission spectra where the superconducting transition frequency is close to the magnetic resonance. Interesting features include output pump and second harmonic pulses that can be strongly modulated with the transmitted pulses being delayed by slow light effect.

We study the quantum dynamics of the center-of-mass momentum distribution for the populations of ... more We study the quantum dynamics of the center-of-mass momentum distribution for the populations of a cold gas with two-level system undergoing spontaneous decay and coupled to a Markovian thermal reservoir at arbitrary temperature. We derive the momentum-convolutionless coupled equations for momentum Fourier transform of the populations which can be easily solved numerically and analytically for a specific internal scheme and for zero-temperature cases. The time and momentum evolutions of the populations are obtained by inverse Fourier transform. The momentum spread and the center-of-mass entropy across one momentum dimension are computed and compared for different internal schemes, between zero-temperature and finite-temperature cases and between and transitions. For initial subrecoil momentum width, the transition displays a two-peak feature. Our results well describe the momentum spread dynamics of cold gas in thermal radiation at early time and complement the results based on Fokker-Planck equation.

The operator solution of a completely quantum mechanical Hamiltonian of the Raman processes is us... more The operator solution of a completely quantum mechanical Hamiltonian of the Raman processes is used here to investigate the possibility of obtaining intermodal entanglement between different modes involved in the Raman processes [e.g., pump mode, Stokes mode, vibration (phonon) mode and anti-Stokes mode]. Intermodal entanglement is reported between (a) pump mode and anti-Stokes mode, (b) pump mode and vibration (phonon) mode, (c) Stokes mode and vibration phonon mode, and (d) Stokes mode and anti-Stokes mode in the stimulated Raman processes for variation of the phase angle of complex eigenvalue alpha(1) of pump mode a. Some incidents of intermodal entanglement in the spontaneous and the partially spontaneous Raman processes are also reported. Further, it is shown that the specific choice of coupling constants may produce genuine entanglement among Stokes mode, anti-Stokes mode, and vibration-phonon mode. It is also shown that the two-mode entanglement not identified by Duan's criterion may be identified by Hillery-Zubairy criteria. It is further shown that intermodal entanglement, intermodal antibunching, and intermodal squeezing are independent phenomena. DOI: 10.1103/PhysRevA.87.022325

Exact solutions are obtained for a collective model of two identical two-level atoms interacting ... more Exact solutions are obtained for a collective model of two identical two-level atoms interacting with a quantized bimodal field with intensity-dependent coupling terms in a lossless cavity. A unitary transformation method is used to solve the time-dependent problem that also gives the eigensolutions of the interaction Hamiltonian. The atomic population dynamics and the dynamics of the photon statistics of the two cavity modes are studied. We present evidence of cooperative effects.

A surface magnon-polariton can be excited by both p- and s-polarized light if at least one of the... more A surface magnon-polariton can be excited by both p- and s-polarized light if at least one of the layers is a magnetic material. We present general expressions of the tangential wave vectors of s- and p-polarized light at an interface of two media. Analysis reveals additional new regimes of surface polariton resonances with magnetic materials for s- and p-polarized light. The tangential wave vectors are found to be equal in magnitude to the normal wave vectors at surface polariton resonances. The spatial distributions of the fields at resonant enhancement and the spectra of the tangential wave vectors are studied for different dielectric permittivities and magnetic permeabilities of the two media. If one of the media has dispersive dielectric function and permeability function, additional surface polariton resonance peaks appear for both s- and p polarizations. For a medium with a superconductor, the tangential component increases asymptotically at lower frequencies, providing subwavelength capability at the terahertz regime. (c) 2012 Optical Society of America

The Casimir force between two plates can be controlled using combinations of dispersive metamater... more The Casimir force between two plates can be controlled using combinations of dispersive metamaterials and nonlinear materials with the optical Kerr effect. The force can be significantly varied and switched between positive and negative values by changing the intensity of a laser pulse. The switching sensitivity increases for small separation between the plates, providing new possibilities of integrating optical devices into nanoelectromechanical systems. DOI: 10.1103/PhysRevA.86.062509

We study the characteristics of ionization rates of an atom by an intense laser field using an ex... more We study the characteristics of ionization rates of an atom by an intense laser field using an extension of Keldysh theory. High-order semianalytical expressions are obtained for linear, circular, and elliptically polarized fields. We compare the features of the new rates with Keldysh analytical results as functions of frequency and electric field strength. The directionality of photoelectron emissions is compared for elliptical, circular, and linearly polarized cases. Laser polarization has significant effects on the ionization spectra and directionality of photoelectron emission.

We study the quantum correlation of photon pairs from a double Raman particle driven by laser fie... more We study the quantum correlation of photon pairs from a double Raman particle driven by laser fields in a modified photon density of states such as a cavity or a defect in a photonic crystal. We obtain an exact semianalytical expression for the photon correlation, which is characterized by two complex decay functions associated with the levels splitting (effective Rabi frequencies) that depend on the control laser field. The position and width of the cavity density of state with respect to the anti-Stokes transition determine the features in the two-photon correlation profile.

Recently, Gerry et al. [Phys. Rev. A 79, 022111 (2009)] studied the violation of the Bell-Clauser... more Recently, Gerry et al. [Phys. Rev. A 79, 022111 (2009)] studied the violation of the Bell-Clauser-Horne-Shimony-Holt inequality for two-spin systems, prepared in an entanglement of spin-coherent states, the so-called entangled spin-coherent states (ESCSs), and found maximal violations for a large class of states. In this paper, using the Holstein-Primakoff realization (HPR) of angular momentum algebra, we present an improved phase estimation scheme employing ESCSs and demonstrate that increasing the spin number gives the smallest variance in the phase parameter in comparison to NOON states under perfect and lossy conditions. The phase sensitivity of this interferometric scheme with parity detection on one of the output states is discussed.

Some years ago Katriel and Solomon [1] described applications to the characterization of the phot... more Some years ago Katriel and Solomon [1] described applications to the characterization of the photon statistics of nonideal lasers, nonclassical light, and deformed photon states using f-deformed coherent states. In this letter, we study the effect of a beam splitter on these nonlinear coherent states. We find that these states are useful for generating quantum entanglement as the deformation parameter gets farther form the unity and for strong input field regimes. The results are confirmed through the Werhl entropy.

We have studied optical pulse propagation in a Raman fiber amplifier doped with a three-level med... more We have studied optical pulse propagation in a Raman fiber amplifier doped with a three-level medium and driven by a control laser pulse. We analyze the spatial-temporal dynamics of pulse propagation for different atomic initial conditions. The propagation of an optical pulse through the amplifier can be sustained by a control laser that induces transparency via quantum coherence, which is useful for extending the distance between optical repeaters. Under certain conditions, amplification is achieved without population inversion. The results could be useful for laser control of optical pulses in amplifiers and waveguides.

We show that it is possible to obtain large field transmission through a periodic structure at fr... more We show that it is possible to obtain large field transmission through a periodic structure at frequencies where the field is lossy in a finite temperature superconductor. The feat is accomplished by using thin superconducting layers. This makes the superconductor photonic crystal useful for transmitting signals over larger distances at higher temperature. Narrow transmission resonances due to surface plasmon effect are damped more quickly with increasing temperature than broader transmission bands. The temperature dependence is useful, particularly for developing optothermal sensors in terahertz and far infrared regimes. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3639288]

Nonlinear optical processes have been used for sensitive detection of chemicals, optical imaging ... more Nonlinear optical processes have been used for sensitive detection of chemicals, optical imaging and spectral analysis of small particles. We have developed an exact theoretical framework to study the angular dependence of coherent anti-Stokes Raman scattering (CARS) intensity in the near field and far field for nanoparticle and microparticle. We obtain exact analytical solution for the CARS signal valid for arbitrary detection distance. Interesting angular dependence is found for nanoparticle, especially with near field detection. The study includes the erects of focused lasers and particle size on the CARS intensity distribution. We find that the detection distance and particle size do not affect the spectroscopic peaks of CARS. However, interference of reflected waves in nanoparticle can produce a dip in the backscattered spectrum.

It is shown that thermal energy from a heat source can be converted to useful work in the form of... more It is shown that thermal energy from a heat source can be converted to useful work in the form of maser-laser light by using a combination of a Stern-Gerlach device and stimulated emissions of excited particles in a maser-laser cavity. We analyze the populations of atoms or quantum dots exiting the cavity, the photon statistics, and the internal entropy as a function of atomic transit time, using the quantum theory of masers and lasers. The power of the laser light is estimated to be sufficiently high for device applications. The thermodynamics of the heat converter is analyzed as a heat engine operating between two reservoirs of different temperature but is generalized to include the change of internal quantum states. The von Neumann entropies for the internal degree are obtained. The sum of the internal and external entropies increases after each cycle and the second law is not violated, even if the photon entropy due to finite photon number distribution is not included. An expression for efficiency relating to the Carnot efficiency is obtained. We resolve the subtle paradox on the reduction of the internal entropy with regards to the path separation after the Stern-Gerlach device.

We present a full quantum theory to study the transient evolution of photon pairs. We introduce a... more We present a full quantum theory to study the transient evolution of photon pairs. We introduce a method which gives exact time-dependent solutions of the coupled quantum Langevin equations for a multilevel quantum particle driven by arbitrary time-dependent laser fields. The analytical solutions are used to develop a numerical code for computing exact time evolution of the two-photon correlation function. We analyze the effects of laser pulses sequence, pulse duration, chirping, and initial internal quantum states on the nonclassicality of the photon correlation through the violation of the Cauchy-Schwarz inequality. The results provide a promising possibility of controlling the generation of highly correlated photon pairs using tailored short laser pulses.

The effect of Kerr nonlinearity on a Lorentz beam is investigated by using the nonlinear Schrodin... more The effect of Kerr nonlinearity on a Lorentz beam is investigated by using the nonlinear Schrodinger (NLS) equation. Based on the variational method, the evolution of a Lorentz beam in a Kerr medium is demonstrated and the critical collapse powers of the Lorentz beam are derived. Numerical simulations of the propagation of a Lorentz beam in a Kerr medium show that the beam becomes quasi-circular in a very short distance. Although the beam width of the Lorentz beam broadens, the central part of the beam give rise to a partial collapse.

The Wigner distribution function (WDF) of a vortex Airy beam is calculated analytically. The WDF ... more The Wigner distribution function (WDF) of a vortex Airy beam is calculated analytically. The WDF provides intuitive pictures of the intriguing features of vorticity in phase space. The nonclassical property of the vortex Airy beam and the Airy beam is analyzed through the negative parts of the WDF. The study shows that destructive interference of certain classical waves can mimic nonclassical lights such as those due to quantum effects.

The propagation of an off-resonant, single-photon pulse in and into a medium of two-level atoms i... more The propagation of an off-resonant, single-photon pulse in and into a medium of two-level atoms is considered. When the pulse is launched from within the medium, there are two propagation speeds, neither of which is the normal group velocity. For densities as small as 10(11) atoms/cm(3) and detunings of order 10(11) s(-1), both propagation speeds approach one half the speed of light in vacuum. Moreover, rather remarkably, there are Rabi oscillations between the field and atomic excitation, even for this single-photon pulse. In contrast, for a pulse sent into the medium, the atom-field system remains adiabatically in a dressed state that propagates with the normal group velocity. In the limit that the index of refraction is approximately equal to unity, we obtain the Fresnel equations for the reflection and transmission coefficients based on this microscopic model. The transmission coefficient differs from the conventional result owing to the fact that we quantize the field in free space.

Extremely intense laser field that makes nonlinear quantum vacuum can be generated by coherent su... more Extremely intense laser field that makes nonlinear quantum vacuum can be generated by coherent superposition of multiple lasers in circular configuration that incorporates optical fibers synchronization scheme and piecewise mirrors in circular array operating below typical damage threshold. Coherent amplification and large laser beams can produce intensity reaching nonlinear quantum vacuum regime. The effects of phase jitter and envelope timing of the pulses due to imperfect synchronization are simulated and analyzed for both linear and circularly polarized pulses. We obtain simple analytical expressions that well describe the envelope jitter and phase jitter. Several practical aspects are discussed, including implications of scaling the laser dimension and pulse duration, with possibility for giant laser facility.

We study the spatial interference pattern of two-photon correlation function for a coherently pha... more We study the spatial interference pattern of two-photon correlation function for a coherently phased linear array of N emitters with a double-Raman scheme, each producing nonclassically correlated photon pairs. The N(2) dependence in the two-photon correlation serves as a coherent amplification method for producing intense nonclassical light. The spatial distribution of the correlation can be controlled by lasers, and depends on the detection configuration. For two coincident detectors, the nonclassical correlation displays the spatial Talbot pattern, but modulated by quantum interference effect. The image revival distance is found to be twice the usual Talbot length. For symmetrically located detectors (X(1) = -X(2)), the correlation displays a distorted Talbot pattern with intricate features and lack of symmetry.

Applied Physics B, 2013

We study the propagation and second harmonic generation of ultrashort pulse in nonlinear photonic... more We study the propagation and second harmonic generation of ultrashort pulse in nonlinear photonic crystal using a combination of Fourier transform and transfer matrix method. The focus is on the reflected and transmitted output of fundamental pump pulse and second harmonic pulse in frequency and time domains, the temperature dependence of the reflection and transmission spectra where the superconducting transition frequency is close to the magnetic resonance. Interesting features include output pump and second harmonic pulses that can be strongly modulated with the transmitted pulses being delayed by slow light effect.

We study the quantum dynamics of the center-of-mass momentum distribution for the populations of ... more We study the quantum dynamics of the center-of-mass momentum distribution for the populations of a cold gas with two-level system undergoing spontaneous decay and coupled to a Markovian thermal reservoir at arbitrary temperature. We derive the momentum-convolutionless coupled equations for momentum Fourier transform of the populations which can be easily solved numerically and analytically for a specific internal scheme and for zero-temperature cases. The time and momentum evolutions of the populations are obtained by inverse Fourier transform. The momentum spread and the center-of-mass entropy across one momentum dimension are computed and compared for different internal schemes, between zero-temperature and finite-temperature cases and between and transitions. For initial subrecoil momentum width, the transition displays a two-peak feature. Our results well describe the momentum spread dynamics of cold gas in thermal radiation at early time and complement the results based on Fokker-Planck equation.

The operator solution of a completely quantum mechanical Hamiltonian of the Raman processes is us... more The operator solution of a completely quantum mechanical Hamiltonian of the Raman processes is used here to investigate the possibility of obtaining intermodal entanglement between different modes involved in the Raman processes [e.g., pump mode, Stokes mode, vibration (phonon) mode and anti-Stokes mode]. Intermodal entanglement is reported between (a) pump mode and anti-Stokes mode, (b) pump mode and vibration (phonon) mode, (c) Stokes mode and vibration phonon mode, and (d) Stokes mode and anti-Stokes mode in the stimulated Raman processes for variation of the phase angle of complex eigenvalue alpha(1) of pump mode a. Some incidents of intermodal entanglement in the spontaneous and the partially spontaneous Raman processes are also reported. Further, it is shown that the specific choice of coupling constants may produce genuine entanglement among Stokes mode, anti-Stokes mode, and vibration-phonon mode. It is also shown that the two-mode entanglement not identified by Duan's criterion may be identified by Hillery-Zubairy criteria. It is further shown that intermodal entanglement, intermodal antibunching, and intermodal squeezing are independent phenomena. DOI: 10.1103/PhysRevA.87.022325

Exact solutions are obtained for a collective model of two identical two-level atoms interacting ... more Exact solutions are obtained for a collective model of two identical two-level atoms interacting with a quantized bimodal field with intensity-dependent coupling terms in a lossless cavity. A unitary transformation method is used to solve the time-dependent problem that also gives the eigensolutions of the interaction Hamiltonian. The atomic population dynamics and the dynamics of the photon statistics of the two cavity modes are studied. We present evidence of cooperative effects.

A surface magnon-polariton can be excited by both p- and s-polarized light if at least one of the... more A surface magnon-polariton can be excited by both p- and s-polarized light if at least one of the layers is a magnetic material. We present general expressions of the tangential wave vectors of s- and p-polarized light at an interface of two media. Analysis reveals additional new regimes of surface polariton resonances with magnetic materials for s- and p-polarized light. The tangential wave vectors are found to be equal in magnitude to the normal wave vectors at surface polariton resonances. The spatial distributions of the fields at resonant enhancement and the spectra of the tangential wave vectors are studied for different dielectric permittivities and magnetic permeabilities of the two media. If one of the media has dispersive dielectric function and permeability function, additional surface polariton resonance peaks appear for both s- and p polarizations. For a medium with a superconductor, the tangential component increases asymptotically at lower frequencies, providing subwavelength capability at the terahertz regime. (c) 2012 Optical Society of America

The Casimir force between two plates can be controlled using combinations of dispersive metamater... more The Casimir force between two plates can be controlled using combinations of dispersive metamaterials and nonlinear materials with the optical Kerr effect. The force can be significantly varied and switched between positive and negative values by changing the intensity of a laser pulse. The switching sensitivity increases for small separation between the plates, providing new possibilities of integrating optical devices into nanoelectromechanical systems. DOI: 10.1103/PhysRevA.86.062509

We study the characteristics of ionization rates of an atom by an intense laser field using an ex... more We study the characteristics of ionization rates of an atom by an intense laser field using an extension of Keldysh theory. High-order semianalytical expressions are obtained for linear, circular, and elliptically polarized fields. We compare the features of the new rates with Keldysh analytical results as functions of frequency and electric field strength. The directionality of photoelectron emissions is compared for elliptical, circular, and linearly polarized cases. Laser polarization has significant effects on the ionization spectra and directionality of photoelectron emission.

We study the quantum correlation of photon pairs from a double Raman particle driven by laser fie... more We study the quantum correlation of photon pairs from a double Raman particle driven by laser fields in a modified photon density of states such as a cavity or a defect in a photonic crystal. We obtain an exact semianalytical expression for the photon correlation, which is characterized by two complex decay functions associated with the levels splitting (effective Rabi frequencies) that depend on the control laser field. The position and width of the cavity density of state with respect to the anti-Stokes transition determine the features in the two-photon correlation profile.

Recently, Gerry et al. [Phys. Rev. A 79, 022111 (2009)] studied the violation of the Bell-Clauser... more Recently, Gerry et al. [Phys. Rev. A 79, 022111 (2009)] studied the violation of the Bell-Clauser-Horne-Shimony-Holt inequality for two-spin systems, prepared in an entanglement of spin-coherent states, the so-called entangled spin-coherent states (ESCSs), and found maximal violations for a large class of states. In this paper, using the Holstein-Primakoff realization (HPR) of angular momentum algebra, we present an improved phase estimation scheme employing ESCSs and demonstrate that increasing the spin number gives the smallest variance in the phase parameter in comparison to NOON states under perfect and lossy conditions. The phase sensitivity of this interferometric scheme with parity detection on one of the output states is discussed.

Some years ago Katriel and Solomon [1] described applications to the characterization of the phot... more Some years ago Katriel and Solomon [1] described applications to the characterization of the photon statistics of nonideal lasers, nonclassical light, and deformed photon states using f-deformed coherent states. In this letter, we study the effect of a beam splitter on these nonlinear coherent states. We find that these states are useful for generating quantum entanglement as the deformation parameter gets farther form the unity and for strong input field regimes. The results are confirmed through the Werhl entropy.

We have studied optical pulse propagation in a Raman fiber amplifier doped with a three-level med... more We have studied optical pulse propagation in a Raman fiber amplifier doped with a three-level medium and driven by a control laser pulse. We analyze the spatial-temporal dynamics of pulse propagation for different atomic initial conditions. The propagation of an optical pulse through the amplifier can be sustained by a control laser that induces transparency via quantum coherence, which is useful for extending the distance between optical repeaters. Under certain conditions, amplification is achieved without population inversion. The results could be useful for laser control of optical pulses in amplifiers and waveguides.

We show that it is possible to obtain large field transmission through a periodic structure at fr... more We show that it is possible to obtain large field transmission through a periodic structure at frequencies where the field is lossy in a finite temperature superconductor. The feat is accomplished by using thin superconducting layers. This makes the superconductor photonic crystal useful for transmitting signals over larger distances at higher temperature. Narrow transmission resonances due to surface plasmon effect are damped more quickly with increasing temperature than broader transmission bands. The temperature dependence is useful, particularly for developing optothermal sensors in terahertz and far infrared regimes. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3639288]

Nonlinear optical processes have been used for sensitive detection of chemicals, optical imaging ... more Nonlinear optical processes have been used for sensitive detection of chemicals, optical imaging and spectral analysis of small particles. We have developed an exact theoretical framework to study the angular dependence of coherent anti-Stokes Raman scattering (CARS) intensity in the near field and far field for nanoparticle and microparticle. We obtain exact analytical solution for the CARS signal valid for arbitrary detection distance. Interesting angular dependence is found for nanoparticle, especially with near field detection. The study includes the erects of focused lasers and particle size on the CARS intensity distribution. We find that the detection distance and particle size do not affect the spectroscopic peaks of CARS. However, interference of reflected waves in nanoparticle can produce a dip in the backscattered spectrum.

It is shown that thermal energy from a heat source can be converted to useful work in the form of... more It is shown that thermal energy from a heat source can be converted to useful work in the form of maser-laser light by using a combination of a Stern-Gerlach device and stimulated emissions of excited particles in a maser-laser cavity. We analyze the populations of atoms or quantum dots exiting the cavity, the photon statistics, and the internal entropy as a function of atomic transit time, using the quantum theory of masers and lasers. The power of the laser light is estimated to be sufficiently high for device applications. The thermodynamics of the heat converter is analyzed as a heat engine operating between two reservoirs of different temperature but is generalized to include the change of internal quantum states. The von Neumann entropies for the internal degree are obtained. The sum of the internal and external entropies increases after each cycle and the second law is not violated, even if the photon entropy due to finite photon number distribution is not included. An expression for efficiency relating to the Carnot efficiency is obtained. We resolve the subtle paradox on the reduction of the internal entropy with regards to the path separation after the Stern-Gerlach device.

We present a full quantum theory to study the transient evolution of photon pairs. We introduce a... more We present a full quantum theory to study the transient evolution of photon pairs. We introduce a method which gives exact time-dependent solutions of the coupled quantum Langevin equations for a multilevel quantum particle driven by arbitrary time-dependent laser fields. The analytical solutions are used to develop a numerical code for computing exact time evolution of the two-photon correlation function. We analyze the effects of laser pulses sequence, pulse duration, chirping, and initial internal quantum states on the nonclassicality of the photon correlation through the violation of the Cauchy-Schwarz inequality. The results provide a promising possibility of controlling the generation of highly correlated photon pairs using tailored short laser pulses.

The effect of Kerr nonlinearity on a Lorentz beam is investigated by using the nonlinear Schrodin... more The effect of Kerr nonlinearity on a Lorentz beam is investigated by using the nonlinear Schrodinger (NLS) equation. Based on the variational method, the evolution of a Lorentz beam in a Kerr medium is demonstrated and the critical collapse powers of the Lorentz beam are derived. Numerical simulations of the propagation of a Lorentz beam in a Kerr medium show that the beam becomes quasi-circular in a very short distance. Although the beam width of the Lorentz beam broadens, the central part of the beam give rise to a partial collapse.

The Wigner distribution function (WDF) of a vortex Airy beam is calculated analytically. The WDF ... more The Wigner distribution function (WDF) of a vortex Airy beam is calculated analytically. The WDF provides intuitive pictures of the intriguing features of vorticity in phase space. The nonclassical property of the vortex Airy beam and the Airy beam is analyzed through the negative parts of the WDF. The study shows that destructive interference of certain classical waves can mimic nonclassical lights such as those due to quantum effects.

The propagation of an off-resonant, single-photon pulse in and into a medium of two-level atoms i... more The propagation of an off-resonant, single-photon pulse in and into a medium of two-level atoms is considered. When the pulse is launched from within the medium, there are two propagation speeds, neither of which is the normal group velocity. For densities as small as 10(11) atoms/cm(3) and detunings of order 10(11) s(-1), both propagation speeds approach one half the speed of light in vacuum. Moreover, rather remarkably, there are Rabi oscillations between the field and atomic excitation, even for this single-photon pulse. In contrast, for a pulse sent into the medium, the atom-field system remains adiabatically in a dressed state that propagates with the normal group velocity. In the limit that the index of refraction is approximately equal to unity, we obtain the Fresnel equations for the reflection and transmission coefficients based on this microscopic model. The transmission coefficient differs from the conventional result owing to the fact that we quantize the field in free space.

Extremely intense laser field that makes nonlinear quantum vacuum can be generated by coherent su... more Extremely intense laser field that makes nonlinear quantum vacuum can be generated by coherent superposition of multiple lasers in circular configuration that incorporates optical fibers synchronization scheme and piecewise mirrors in circular array operating below typical damage threshold. Coherent amplification and large laser beams can produce intensity reaching nonlinear quantum vacuum regime. The effects of phase jitter and envelope timing of the pulses due to imperfect synchronization are simulated and analyzed for both linear and circularly polarized pulses. We obtain simple analytical expressions that well describe the envelope jitter and phase jitter. Several practical aspects are discussed, including implications of scaling the laser dimension and pulse duration, with possibility for giant laser facility.

We study the spatial interference pattern of two-photon correlation function for a coherently pha... more We study the spatial interference pattern of two-photon correlation function for a coherently phased linear array of N emitters with a double-Raman scheme, each producing nonclassically correlated photon pairs. The N(2) dependence in the two-photon correlation serves as a coherent amplification method for producing intense nonclassical light. The spatial distribution of the correlation can be controlled by lasers, and depends on the detection configuration. For two coincident detectors, the nonclassical correlation displays the spatial Talbot pattern, but modulated by quantum interference effect. The image revival distance is found to be twice the usual Talbot length. For symmetrically located detectors (X(1) = -X(2)), the correlation displays a distorted Talbot pattern with intricate features and lack of symmetry.