Physical Review A

We develop a general approach for monitoring and controlling evolution of open quantum systems. In contrast to the master equations describing time evolution of density operators, here, we formulate a dynamical equation for the evolution of the process matrix acting on a system. This equation is app...

We demonstrate how gradient ascent pulse engineering optimal control methods can be implemented on donor-electron-spin qubits in Si semiconductors with an architecture complementary to the original Kane’s proposal. We focus on the high-fidelity-controlled-NOT (CNOT) gate and explicitly find its di...

We give a sufficient criterion that guarantees that a many-body quantum system can be controlled by properly manipulating the (local) Hamiltonian of one of its subsystems. The method can be applied to a wide range of systems: it does not depend on the details of the couplings but only on their assoc...

We report the experimental realization of entanglement localization which restores the polarization entanglement completely redirected after a linear coupling with incoherent and noisy surrounding photon. The method based only on measurements of the surrounding photon after the coupling and on posts...

We propose and theoretically analyze an experimental configuration in which lasers induce three-spin interactions between trapped ions. By properly choosing the intensities and frequencies of the lasers, three-spin couplings may be dominant or comparable to two-spin terms and magnetic fields. In thi...

We suggest a method of entangling significantly the distant ends of a spin chain using minimal control. This entanglement between distant individual spins is brought about solely by exploiting the dynamics of an initial mixed state with Néel order if the lattice features nearest-neighbor XXZ inte...

We study the reduced fidelity between local states of lattice systems exhibiting topological order. By exploiting mappings to spin models with classical order, we are able to analytically extract the scaling behavior of the reduced fidelity at the corresponding quantum phase transitions out of the t...

The 2 ³P₁–2 ³P₂ interval in helium is measured using microwave separated oscillatory fields. Our measured result is 2 291 177.53±0.35 kHz . A disagreement with theory of over 15 kHz indicates a major problem with two-electron QED calculations. If this disagreement is resolved, measu...

A fully relativistic restricted active space configuration-interaction method is employed to compute the P -odd electron-nucleus interaction constant W_A for the ground (²Σ_1/2) state of BaF, which yields the result of W_A=160 Hz . Our present estimated result of the P -odd interaction consta...

Very accurate variational calculations of the fundamental pure vibrational transitions of the ³He ⁴He⁺ and ⁷LiH⁺ ions are performed within the framework that does not assume the Born-Oppenheimer (BO) approximation. The non-BO wave functions expanded in terms of one-center explicitly correlated...

We present a rigorous study of low-temperature collisions of polar molecules and atoms in a microwave laser field. Our calculations show that inelastic relaxation of molecules in a microwave cavity may occur through collision-induced absorption of photons stimulated by the anisotropy of the atom-mol...

We report measurement of the inelastic and elastic collision rates for ⁸⁸Sr atoms in the (5s5p)³P₀ state in a crossed-beam optical dipole trap. Since the (5s5p)³P₀ state is the lowest level of the triplet manifold, large loss rates indicate the importance of principle-quantum-number-changing c...

A Fermi-Fermi mixture of ⁴⁰K and ⁶Li does not exhibit the Efimov effect in a free space, but the Efimov effect can be induced by confining only ⁴⁰K in one dimension. Here the Efimov’s three-body parameter is controlled by the confinement length. We show that the three-body recombination rate...

Considering a Xe atom endohedrally confined in C₆₀ , we predict the formation of another type of atom-fullerene hybrid states. These dimer-type states arise from the near degeneracy of inner levels in contrast to the known overlap-induced hybrid states around the Fermi level of smaller compounds. T...

We demonstrate runaway evaporative cooling directly with a tightly confining optical-dipole trap and achieve fast production of condensates of 1.5×10^{5 87}Rb atoms. Our scheme uses a misaligned crossed-beam far off-resonance optical-dipole trap (MACRO-FORT). It is characterized by independent con...

A method for decelerating a continuous beam of neutral polar molecules is theoretically demonstrated. This method utilizes nonuniform static electric fields and regions of adiabatic population transfer to generate a mechanical force that opposes the molecular beam’s velocity. By coupling this tech...

Ultrafast dynamics of excited molecules is studied through time-resolved two-vacuum-ultraviolet (vuv)-photon ionization using a nonlinear volume autocorrelator unit. The two-vuv-photon process is induced by the intense fifth harmonic radiation of a femtosecond Ti:sapphire laser. In a proof-of-princi...

Impulsive Raman transition on the B ³Î (0_u⁺) state of the iodine molecule is reported. Several rovibrational states in the B state are populated with the second harmonics of a neodymium-doped yttrium lithium fluoride (Nd:YLF) laser ( ≤250 ns , 527 nm). The population alteration with Δv=Â...

We have produced ultracold heteronuclear YbRb^∗ molecules in a combined magneto-optical trap by photoassociation. The formation of electronically excited molecules close to the dissociation limit was observed by the trap loss spectroscopy in mixtures of ⁸⁷Rb with ¹⁷⁴Yb and ¹⁷⁶Yb . The molecu...

Fully classical three-dimensional ensembles are examined under conditions of nonsequential double ionization and are shown to have trajectories in which both electrons apparently ionize only to have one electron bound to the nucleus after the laser pulse. These trajectories feature recollision excit...

We present the experimental demonstration of nondestructive probing of the ¹S₀-³P₀ clock transition probability in an optical lattice clock with ⁸⁷Sr atoms. It is based on the phase shift induced by the atoms on a weak off-resonant laser beam. The method we propose is a differential measurement ...

Nonadiabatic transitions are known to be major loss channels for atoms in magnetic traps but have thus far not been experimentally reported upon for trapped molecules. We have observed and quantified losses due to nonadiabatic transitions for three isotopologues of ammonia in electrostatic traps by ...

We study polarization effects of two-component atomic Fermi gases loaded on three-leg triangular optical lattice by using the density-matrix renormalization-group method. Concentrating on a case in which a Mott phase coexists with metallic ones, we observe plateulike structures in the Mott phase pol...

We show that thermalization and the breakdown of integrability in the one-dimensional Lieb-Liniger model caused by local three-body elastic interactions is suppressed by pairwise quantum correlations when approaching the strongly correlated regime. If the relative momentum k is small compared to t...

We propose an experimental procedure to cool fermionic atoms loaded into an optical lattice. The central idea is to spatially divide the system into entropy-rich and -poor regions by shaping the confining potential profile. Atoms in regions of high entropy per particle are subsequently isolated from...

We study the many-body state of ultracold bosons in a bistable optical lattice potential in an optomechanical resonator in the weak-coupling limit. Interesting physics arises as a result of bistability and discontinuous jumps in the cavity field. Of particular interest is the situation where the opt...

We experimentally studied the evolution of quasieigenmodes as classical dynamics undergoing a transition from being regular to chaotic in open quantum billiards. In a deformation-variable microcavity, we traced all high- Q cavity modes in a wide range of frequency as the cavity deformation increase...

Multi-normal-mode splitting peaks are experimentally observed in a system with Doppler-broadened two-level atoms inside a relatively long optical cavity. In this system, the atom-cavity interaction can reach the “superstrong-coupling” condition with atom-cavity coupling strength gsqrt[N] to b...

This work presents a theory of the frequency-resolved light emission of active two-dimensional dielectric microresonators, which are characterized by a highly nonparaxial mode structure and frequently feature a position-dependent dielectric constant and nonuniform gain. The Lorentzian intensity prof...

Einstein, Podolsky, and Rosen brought up a state with momenta of two particles anticorrelated, which introduced the concept of entanglement and excited many interesting studies. In contrast, we propose an experimental scheme to prepare and identify two-photon momentum positively correlated entanglem...

We develop a general approach for monitoring and controlling evolution of open quantum systems. In contrast to the master equations describing time evolution of density operators, here, we formulate a dynamical equation for the evolution of the process matrix acting on a system. This equation is app...

We present the analytical solution in closed form for the semiclassical limit of the quantum-mechanical Coulomb Green’s function in position space in n dimensions. We utilize a projection method which has its roots in Lambert’s theorem and which allows us to treat the system as an essentially ...

The set of entanglement measures proposed by Hein, Eisert, and Briegel for n -qubit graph states [Phys. Rev. A 69, 062311 (2004)] fails to distinguish between inequivalent classes under local Clifford operations if n≥7 . On the other hand, the set of invariants proposed by van den Nest, Dehaene,...

We have further extended the two-step approach developed by Chung and Chew [N. N. Chung and L. Y. Chew, Phys. Rev. A 76, 032113 (2007)] to the solution of the quantum dynamics of general systems of N -coupled anharmonic oscillators. The idea is to employ an optimized basis set to represent the dyna...

We study the many-body state of ultracold bosons in a bistable optical lattice potential in an optomechanical resonator in the weak-coupling limit. Interesting physics arises as a result of bistability and discontinuous jumps in the cavity field. Of particular interest is the situation where the opt...

We experimentally studied the evolution of quasieigenmodes as classical dynamics undergoing a transition from being regular to chaotic in open quantum billiards. In a deformation-variable microcavity, we traced all high- Q cavity modes in a wide range of frequency as the cavity deformation increase...

The coupled-wave equations of three-wave interactions are generalized into three dimensions. The reciprocal lattice vectors (RLVs) of three-dimensional (3D) nonlinear photonic crystals (NPCs) which show some unique properties are analyzed in detail as compared to those in one- and two-dimensional ca...

The paper continues the analysis of vacuum Rabi oscillations we started in part I [Phys. Rev. A 79, 033836 (2009)]. Here we concentrate on experimental consequences for cavity QED of two different classes of representations of harmonic-oscillator Lie algebras. The zero-temperature master equation, d...

The propagation of probe and coupling optical beams through a four-level coherent media is modeled by two coupled nonlinear Schrödinger equations. The nonlinear susceptibilities exhibited by the four-level media are calculated in the nonperturbative regime, i.e., considering the probe and coupling ...

We report on light slowing down in a rare-earth-metal-ion-doped crystal by persistent spectral hole burning. The absence of motion of the active ions, the large inhomogeneous broadening, the small homogeneous width, and the long lifetime of the hyperfine shelving states make this material convenient...

Soliton pulses in normally dispersive mode-locked lasers are considered using a nonlinear Schrödinger equation, appropriately modified to model power (intensity) and energy saturations. Strongly chirped, localized pulses are obtained when the effects of nonlinearity, dispersion, saturated gain, fil...

Direct measurement of photon bunching ( g₍₂₎ correlation function) in one output arm of a spontaneous-parametric-down-conversion source operated with a continuous pump laser in the single-photon regime is demonstrated. The result is in agreement with the statistics of a thermal field of the same co...

We propose a special cavity design that is constructed by terminating a one-dimensional waveguide with a perfect mirror at one end and doping a two-level atom at the other. We show that this atom plays the intrinsic role of a semitransparent mirror for single-photon transports such that quasinormal ...

The effect of a random-phase diffuser on fluctuations of laser light (scintillations) is studied. Not only spatial but also temporal phase variations introduced by the phase diffuser are analyzed. The explicit dependence of the scintillation index on finite-time phase variations is obtained for long...

A system of coherently coupled nonlinear Schrödinger equations relevant to the polarization of light beams is considered. Modulation instability (MI) of plane waves is studied without approximations and two results were presented: (1) MI will be enhanced for a finite birefringence, thus extending e...

The ground-state fidelity has been introduced recently as a tool to investigate quantum phase transitions. Here, we apply this concept in the context of a crossover problem. Specifically, we calculate the fidelity susceptibility for the BCS ground-state wave function, when the intensity of the fermi...

The situation where the quantum Cramér-Rao inequality for a general measurement becomes equality is analyzed in some detail in the case of a family of pure states. In particular, it turns out that under some natural assumptions, the measurement in question is simple, and the states must have a spec...

We investigate the feasibility of carrying out quantum walks with cold atoms in a double optical lattice. Monte Carlo simulations of time-of-flight (TOF) detection and absorption imaging were carried out, focusing on a specific experimental implementation. These indicate that absorption imaging woul...

We present analytic descriptions of atomic interaction at ultracold temperatures using both single-channel and multichannel quantum-defect theories. In the case of a single channel, addressed in this paper, the expansion of Gao [Phys. Rev. A 58, 4222 (1998)] is generalized to higher orders for angul...

We consider a two-step process that may occur in relativistic ion-atom collisions. In this process, within a single ion-atom collision, an atomic electron is captured by the ion via the radiative and/or nonradiative capture channels, while the colliding nuclei of the atom and ion simultaneously prod...

The quantitative rescattering theory (QRS) for high-order harmonic generation (HHG) by intense laser pulses is presented. According to the QRS, HHG spectra can be expressed as a product of a returning electron wave packet and the photorecombination differential cross section of the laser-free contin...

Full three-dimensional (3D) calculations of small two-component Fermi gases under highly elongated confinement, in which unlike fermions interact through short-range potentials with variable atom-atom s -wave scattering length, are performed using the correlated Gaussian approach. In addition, micr...

We consider a periodic lattice loaded with pairs of bosonic atoms tightly bound to each other via strong attractive on-site interaction that exceeds the intersite tunneling rate. An ensemble of such lattice dimers is accurately described by an effective Hamiltonian of hard-core bosons with strong ne...

The binding energy and fine-structure splittings of the arsenic negative ion (As⁻) have been measured using infrared photodetachment threshold spectroscopy. The relative cross section for neutral atom production was measured with a crossed ion-beam-laser-beam apparatus over selected photon energ...

In this work we present solid state nuclear magnetic resonance (NMR) experiments to study decoherence in the dynamics of many-spin systems. We characterize the global Loschmidt echo (LE) and the distribution of multiple quantum coherence orders during the evolution under dipolar and double quantum Hamiltonians. To study an infinite 1H system and a closed cluster of nuclear spins we use polycrystalline adamantane and the liquid crystal 5CB in the nematic mesophase, respectively as model systems. The infinite or finite nature of the system is clearly manifested through spin counting measurements. Comparison between experimental and numerical results gives insights on the decoherence mechanisms in these systems. Contrastingly, the dominating mechanism in 5CB affects all coherence orders in the same way, while in adamantane higher orders of coherence decay faster than the lower ones.

We show that bipartite entanglement distribution (or entanglement of assistance) in multipartite quantum systems is by nature polygamous. We first provide an analytic upper bound for the concurrence of assistance in bipartite quantum systems, and derive a polygamy inequality of multipartite entanglement in arbitrary dimensional quantum systems.

We propose a continuous time quantum search algorithm using a generalization of the Jaynes-Cummings model. In this model the states of the atom are the elements among which the algorithm realizes the search, exciting resonances between the initial and the searched states. This algorithm behaves like Grover's algorithm; the optimal search time is proportional to the square root of the size of the search set and the probability to find the searched state oscillates periodically in time. In this frame, it is possible to reinterpret the usual Jaynes-Cummings model as a trivial case of the quantum search algorithm.

This paper generalizes and expands upon the work where we introduced a scheme for fault-tolerant holonomic quantum computation (HQC) on stabilizer codes. HQC is an all-geometric strategy based on non-Abelian adiabatic holonomies, which is known to be robust against various types of errors in the control parameters. The scheme we present shows that HQC is a scalable method of computation and opens the possibility for combining the benefits of error correction with the inherent resilience of the holonomic approach. We show that with the Bacon-Shor code the scheme can be implemented using Hamiltonian operators of weight 2 and 3.

In this paper, we propose to use the decoy-state technique to improve the security of the quantum key distribution (QKD) systems based on homodyne detection against the photon number splitting (PNS) attack. The decoy-state technique is a powerful tool that can significantly boost the secure transmission range of the QKD systems. However it has not yet been applied to the systems that use coherent detection. After adapting this theory to the systems based on homodyne detection, we quantify the secure performance and transmission range of the resulting system.

The interacting and the Kohn-Sham static density-density response functions for different one-dimensional two-electron singlet systems are reconstructed numerically. From their inverse we obtain the exact static exchange correlation kernel. This quantity represents the adiabatically exact approximation of the frequency-dependent exchange correlation kernel that is crucial for time-dependent linear density response theory. We investigate its performance for nonlocal perturbations and analyze its sum rule properties. We also compute the adiabatically exact transition energies that follow from the static kernel within linear response theory.

We report on the experimental determination of the palladium L-subshell Coster-Kronig (CK) transition yields via high-resolution measurements of the La1,2 (L3-M4,5) and Lb1 (L2-M4) x-ray emission lines. The L x-ray spectra were recorded by means of curved crystal spectrometers employing energy-tunable synchrotron radiation for fluorescence production. The CK yields were derived from the relative L x-ray intensity jumps at the L-edges by fitting the fluorescence intensities as a function of the photon energy to the photoionization cross sections. The L x-ray intensities were corrected for solid-state effects which were estimated from the comparison of the measured and theoretical Pd L-edge x-ray absorption spectrum. Thanks to high-resolution, the partial CK yield f13L1L3M could be extracted from the intensities of the resolved LaM satellite transitions. For f23, f12 and f13 CK rates, values of 0.1640.033, 0.0470.001 and 0.7300.039 were found, respectively. For the partial CK yields f13L1L3M and f13L1L3N, results of 0.4060.023 and 0.3240.032, respectively, were obtained.

We calculate the relativistic corrections of relative order (Za)2 to the two-photon decay rate of higher excited S and D states in ionic atomic systems, and we also evaluate the leading radiative corrections of relative order a(Za)2 nbsp;ln[(Za)-2]. We thus complete the theory of the two-photon decay rates up to relative order a3 nbsp;ln(a). An approach inspired by nonrelativistic quantum electrodynamics is used. We find that the corrections of relative order (Za)2 to the two-photon decay are given by the zitterbewegung, the spin-orbit coupling and by relativistic corrections to the electron mass, and by quadrupole interactions. We show that all corrections are separately gauge-invariant with respect to a "hybrid" transformation from velocity to length gauge, where the gauge transformation of the wave function is neglected. The corrections are evaluated for the two-photon decay from 2S, 3S, 3D, and 4S states in one-electron (hydrogenlike) systems, with 1S and 2S final states.

The charge transfer in collisions of C sup 2+ ions with the CO molecule and the OH radical have been studied theoretically by means of ab-initio quantum chemistry molecular methods followed by a semiclassical dynamical treatment in the keV collision energy range. The comparison of the cross-sections calculated for these two collision systems exhibits interesting features with regard to the anisotropy of these processes and the influence of the vibration of the molecular target.

We show theoretically that a vacuum-clad silica-core fiber can focus a perpendicularly incident light onto one or several lines parallel to the fiber axis. We demonstrate numerically that such a focusing action of the fiber can be used to trap and guide atoms along the fiber with a red- or blue-detuned incident light.

The multiphoton dissociation branching ratios for H2+ and D2+ as a function of laser peak intensity and pulse length are investigated by solving the time-dependent Schr#246;dinger equation in the Born-Oppenheimer approximation, neglecting nuclear rotation. An 800nbsp;nm laser pulse with peak intensities from 8times;109nbsp;W/cm2 to 1014nbsp;W/cm2 and pulse lengths from 5nbsp;fs to 7.5nbsp;fs is used. We also investigate the viability of identifying zero-, one-, two-, and three-photon processes based only on the nuclear kinetic energy release spectrum, and check these identifications with a rigorous Floquet-like method.

We investigate the coherent control of a single particle held in a quartic double-well with a symmetric or asymmetric driving and exhibit time-evolutions of relative probability of the particle in one of the double-well wells. It is shown analytically and numerically that the coherent destruction of tunneling could occur only for the symmetric intense driving, and application of the asymmetric sawtooth driving leads to increase of the tunneling rate. The results agree with the recent experimental data reported by E. Kierig et al. [Phys. Rev. Lett. 100, 190405(2008)]. We also exhibit the effect of multiple photon resonances on the tunneling, through a dc field. Finally, we demonstrate a connection between the classically chaotic barrier-crossing and quantum tunneling numerically.

The time-dependent multi-configuration Hartree method is optimized for intense laser dynamics and applied to nonsequential double ionization in a two electron diatomic model molecule with two dimensions per electron. The efficiency of our method brings these calculations from the realm of large scale computation facilities to single processor machines. The resulting two-electron spectrum exhibits pronounced signatures from which the ionic bound states involved in nonsequential double ionization are retrieved with the help of a semi-classical model. A mechanism for the ionization dynamics is suggested.

We propose to use a quantized version of coherent two-color photoassociation to realize a hybrid device for quantum control of light. The dynamical features of this system are exhibited, including the slowing down or storage of light and the molecular matter-wave solitons. This may indicate a hybrid atom-molecule quantum device for storage and retrieve of optical information.

Strong 1D lattices usually lead to unconnected two-dimensional gases. The long-range character of the dipole-dipole interactions leads to a novel scenario where non-overlapping gases at different sites may interact significantly. We show that the excitations of non-overlapping condensates in 1D optical lattices acquire a band-like character, being collectively shared by different sites. In particular, the hybridization of the modes significantly enhances the rotonization of the excitations, and may induce roton-instability. We discuss the observability of this effect in on-going experiments.

We consider the manipulation of Bose-Einstein condensate vortices by optical potentials generated by focused laser beams. It is shown that for appropriate choices of the laser strength and width it is possible to successfully transport vortices to various positions inside the trap confining the condensate atoms. Furthermore, the full bifurcation structure of possible stationary single-charge vortex solutions in a harmonic potential with this type of impurity is elucidated. The case when a moving vortex is captured by a stationary laser beam is also studied, as well as the possibility of dragging the vortex by means of periodic optical lattices.

We investigate the spatially dependent relative phase evolution of an elongated two-component Bose-Einstein condensate. The pseudo-spin-\tfrac12 system is comprised of the and hyperfine ground states of , which we magnetically trap and interrogate with radio-frequency and microwave fields. We probe the relative phase evolution with Ramsey interferometry and observe a temporal decay of the interferometric contrast well described by a mean-field formalism. Inhomogeneity of the collective relative phase dominates the loss of interferometric contrast, rather than decoherence or phase diffusion. We demonstrate a technique to simultaneously image each state, yielding sub percent variations in the measured relative number whilst preserving the spatial mode of each component. In addition we propose a spatially sensitive interferometric technique to image the relative phase.

We study a trapped system of fermions with a zero-range two-body interaction using the Shell-Model Monte Carlo method, providing ab initio results for the low particle number limit where mean-field theory is not applicable. We present results for the N-body energies as function of interaction strength, particle number, and temperature. The subtle question of renormalization in a finite model space is addressed and the convergence of our method and its applicability across the BCS-BEC crossover is discussed. Our findings indicate that very good quantitative results can be obtained on the BCS side, whereas at unitarity and in the BEC regime the convergence is less clear. Comparison to N=2 analytics at zero and finite temperature, and to other calculations in the literature for N > 2 show very good agreement.

Relativistic optical rectification is analyzed by utilizing the analytical solutions of the three-dimensional collective electron motion driven by a high-intensity pulsed Gaussian beam. Under the paraxial expansion the slowly varying components in the nonlinear oscillation of electron density and electric current are extracted from the solutions first, then they are used in the Maxwell equations as the source terms to calculate the terahertz electromagnetic fields as functions of the spatiotemporal amplitude of the pulsed Gaussian beam. The analysis compares well with available experimental data and computer simulations, and demonstrates the general scheme of paraxial expansion for the analysis of relativistic nonlinear optical interactions.

We examine the quantum correlations at steady state in a three-mode quantum-beat laser that operates well above threshold. The analysis is presented by employing the dressed-atom combination-mode picture, in which only one combination mode of three cavity fields is coupled to the active medium, while the other two combination modes are decoupled. For suitable operating conditions, the coupled mode has the intensity fluctuations below the shot noise, while the two decoupled modes retain in their vacuum states. This determines that all of the original modes exhibit sub-Poissonian statistics. When the system operates well above threshold, the van Loock-Furusawa inequality is satisfied, concluding that the genuine tripartite entanglement among three sub-Poissonian fields is established. Physically, the responsible mechanism is the combined effect of atomic coherence controlled correlated-spontaneous emission and intrinsic feedback.

We propose a technique capable of imaging a distinct physical object with sub-Rayleigh resolution in an ordinary far-field imaging setup using single-photon sources and linear optical tools only. We exemplify our method for the case of a rectangular aperture and two or four single-photon emitters obtaining a resolution enhanced by a factor of two or four, respectively.

We introduce an effective numerical method of density matrix determination of fiber coupled single photon generated in process of spontaneous parametric down conversion in type I non-collinear configuration. The presented theory has been successfully applied in case of source utilized to demonstrate the experimental characterization of spectral state of single photon, what was reported in Phys. Rev. Lett. 99, 123601 (2007).

We discuss stationary light created by a pair of counter-propagating control fields in L-type atomic gases with electromagnetically induced transparency for the case of negligible Doppler broadening. In this case the secular approximation used in the discussion of stationary light in hot vapors is no longer valid. We discuss the quality of the effective light-trapping system and show that in contrast to previous claims it is finite even for vanishing ground-state dephasing. The dynamics of the photon loss is in general non exponential and can be faster or slower than in hot gases.

We study the properties of two-color nonlinear localized modes which may exist at the interfaces separating two different periodic photonic lattices in quadratic media, focussing on the impact of phase mismatch of the photonic lattices on the properties, stability, and threshold power requirements for the generation of interface localized modes. We employ both an effective discrete model and continuum model with periodic potential and find good qualitative agreement between both models. Dynamics excitation of interface modes shows that, a two-color interface twisted mode splits into two beams with different escaping angles and carrying different energies when entering a uniform medium from the quadratic photonic lattice. The output position and energy contents of each two-color interface solitons can be controlled by judicious tuning of the lattice parameters.

We quantify noise-induced phase deviations of dispersion-managed solitons (DMS) in optical fiber communications and femtosecond lasers. We first develop a perturbation theory for the dispersion-managed nonlinear Schr#246;dinger equation (DMNLSE) in order to compute the noise-induced mean and variance of the soliton parameters. We then use the analytical results to guide importance-sampled Monte-Carlo simulations of the noise-driven DMNLSE. Comparison of these results with those from the original, un-averaged, governing equations confirm the validity of the DMNLSE as a model for many dispersion-managed systems, and quantify the increased robustness of DMS with respect to noise-induced phase jitter.