Multiphoton Interaction Research Articles

Genuine non-Gaussian entanglement of light and quantum coherence for an atom from noisy multiphoton spin-boson interactions

Harnessing entanglement and quantum coherence plays a central role in advancing quantum technologies. In quantum optical light-atom platforms, these two fundamental resources are often associated with a Jaynes-Cummings model description describing the coherent exchange of a photon between an optical resonator mode and a two-level spin. In a generic nonlinear spin-boson system, more photons and more modes will take part in the interactions. Here we consider such a generalization: the two-mode multiphoton Jaynes-Cummings (MPJC) model. We demonstrate how entanglement and quantum coherence can be optimally generated and subsequently manipulated in experimentally accessible parameter regimes. A detailed comparative analysis of this model reveals that nonlinearities within the MPJC interactions produce genuinely non-Gaussian entanglement, devoid of Gaussian contributions, from noisy resources. More specifically, strong coherent sources may be replaced by weaker, incoherent ones, significantly reducing the resource overhead, though at the expense of reduced efficiency. At the same time, increasing the multiphoton order of the MPJC interactions expedites the entanglement generation process, thus rendering the whole generation scheme again more efficient and robust. We further explore the use of additional dispersive spin-boson interactions and Kerr nonlinearities in order to create spin coherence solely from incoherent sources and to enhance the quantum correlations, respectively. As for the latter, somewhat unexpectedly, there is not necessarily an increase in quantum correlations due to the augmented nonlinearity. Towards possible applications of the MPJC model, we show how, with appropriately chosen experimental parameters, we can engineer arbitrary NOON states as well as the tripartite W state. Published by the American Physical Society 2024

Coherent Quantum Network of Superconducting Qubits as a Highly Sensitive Detector of Microwave Photons for Searching of Galactic Axions

We propose a novel approach to detect a low power microwave signal with a frequency of the order of several GHz based on a coherent collective response of quantum states occurring in a superconducting qubits network (SQN). An SQN composes of a large number of superconducting qubits embedded in a low-dissipative superconducting resonator. Our theory predicts that an SQN interacting with the off-resonance microwave radiation, demonstrates the collective alternating current Stark effect that can be measured even in the limit of single photon counting. A design of the layout of three terminals SQN detectors containing 10 flux qubits weakly coupled to a low-dissipative R-resonator and T-transmission line was developed. The samples were fabricated by Al-based technology with Nb resonator. The SQN detector was tested in terms of microwave measurements of scattering parameters and two-tone spectroscopy. A substantial shift of the frequency position of the transmission coefficient drop induced by a second tone pump signal was observed, and this effect clearly manifests a nonlinear multiphoton interaction between the second-tone microwave pump signal and an array of qubits.

The effect of intrinsic decoherence on the dynamics of an Ξ-type qutrit system interacting with a coherent field

This paper solves milburn’s intrinsic noise (IN) model for a 3-level atom of an Ξ-type interacting with a coherent cavity field via multiphoton transitions. Therefore, the effects of the intrinsic noise and the multi-photon interactions are investigated for some quantum phenomena, such as total correlation, entanglement, and atomic inversion. In general, we found that the collapse-revival phenomenon occurs during the oscillatory behaviour of atomic population dynamics. In addition, the birth-death phenomenon is observed in the negativity dynamics. Entropy, negativity, and mutual information have various dynamics. It is found that, as the entropy increases, the negativity and mutual information diminish to stationary levels. When intrinsic noise is considered, all the phenomena of atomic inversion, entropies, negativity and mutual information exhibit high sensitivity to high intrinsic noise values, except the mutual information dynamics, which is more resistant than that of the other quantifiers.

Laser-induced Coulomb explosion imaging of alkali-metal dimers on helium nanodroplets

Alkali dimers, $\mathrm{Ak}_2$, residing on the surface of He nanodroplets are doubly ionized due to multiphoton absorption from an intense, 50-fs laser pulse leading to fragmentation into a pair of alkali cations. Based on the measured kinetic energy distributions, $P(E_{\text{kin}})$, of the $\mathrm{Ak}^+$ fragment ions, we retrieve the distribution of internuclear distances, $P(R)$, via the $\mathrm{Ak}_2^{2+}$ potential curve. Results are obtained for $\mathrm{{Na}_2}$, $\mathrm{K}_2$, $\mathrm{Rb}_2$, and $\mathrm{Cs}_2$ in both the 1 $^1\Sigma_{g}^+$ ground state and in the lowest-lying triplet state 1 $^3\Sigma_{u}^+$, and for $\mathrm{Li}_2$ in the 1 $^3\Sigma_{u}^+$ state. For $\mathrm{Li}_2$, $\mathrm{K}_2$, and $\mathrm{Rb}_2$, the center of the measured $P(R)$'s is close to the center of the wave function, $\Psi(R)$, of the vibrational ground state in the 1 $^1\Sigma_{g}^+$ and 1 $^3\Sigma_{u}^+$ states, whereas for $\mathrm{{Na}_2}$ and $\mathrm{{Cs}_2}$ small shifts are observed. For all the $\mathrm{{Ak}_2}$, the width of the measured $P(R)$ is broader than $|\Psi(R)|^2$ by a factor of 2-4. We discuss that resonance effects in the multiphoton ionization and interaction of the $\mathrm{Ak}^+$ ion with the He droplet give rise to the observed deviations of $P(R)$ from $|\Psi(R)|^2$. Despite these deviations, we deem that timed Coulomb explosion will allow imaging of vibrational wave packets in alkali dimers on He droplets surfaces.

A Framework for Biosensors Assisted by Multiphoton Effects and Machine Learning.

The ability to interpret information through automatic sensors is one of the most important pillars of modern technology. In particular, the potential of biosensors has been used to evaluate biological information of living organisms, and to detect danger or predict urgent situations in a battlefield, as in the invasion of SARS-CoV-2 in this era. This work is devoted to describing a panoramic overview of optical biosensors that can be improved by the assistance of nonlinear optics and machine learning methods. Optical biosensors have demonstrated their effectiveness in detecting a diverse range of viruses. Specifically, the SARS-CoV-2 virus has generated disturbance all over the world, and biosensors have emerged as a key for providing an analysis based on physical and chemical phenomena. In this perspective, we highlight how multiphoton interactions can be responsible for an enhancement in sensibility exhibited by biosensors. The nonlinear optical effects open up a series of options to expand the applications of optical biosensors. Nonlinearities together with computer tools are suitable for the identification of complex low-dimensional agents. Machine learning methods can approximate functions to reveal patterns in the detection of dynamic objects in the human body and determine viruses, harmful entities, or strange kinetics in cells.

A comparative Study of Atomic Entanglement in Single Mode Jaynes Cummings Model with Multiphoton Interaction

A comparative Study of Atomic Entanglement in Single Mode Jaynes Cummings Model with Multiphoton Interaction

Coherent manipulation of trapped Rb atoms by overlapping frequency-chirped laser pulses: theory and experiment

We present results of experimental and theoretical studies of coherent momentum transfer to rubidium atoms in a magneto-optical trap by pairs of counter-propagating frequency-modulated (chirped) laser pulses. The counter-propagating pulse pairs partially overlap each other leading to multiphoton interaction processes. We show experimentally that the mechanical momentum transferred to atoms in this scheme of interaction is larger than in the case of non-overlapping pulse pairs acting separately on the atoms. Results of numerical simulations that take into account all relevant hyperfine energy states of Rb along with the influence of relaxation and re-pumping processes are in good agreement with obtained experimental results.Graphical abstract

High Harmonic Generation in Triangular Graphene Quantum Dots

Higher harmonic generation in plane graphene quantum dots initiated by intense coherent radiation is investigated using dynamical Hartree–Fock mean-field theory. A microscopic theory describing the extreme nonlinear optical response of plane graphene quantum dots is developed. The closed set of differential equations for the single-particle density matrix at the multiphoton interaction of graphene quantum dots and strong laser field is solved numerically. The obtained solutions indicate the significance of the type of edge and lateral size and the band gap and laser field strength in the process of high harmonic generation in the triangular graphene quantum dot.

Laser Direct Writing of Graphene Quantum Dots inside a Transparent Polymer.

Graphene quantum dots (GQDs) have emerged as a promising new class of environmentally friendly quantum dots with unique properties. However, the limitations of synthesis and patterning methods have hindered GQDs from displaying their true potentials to date. Here, we demonstrate the simultaneous synthesis and patterning of GQDs for the first time inside a transparent polymer, polydimethylsiloxane (PDMS), using femtosecond laser pulses. By focusing and scanning femtosecond laser pulses, arbitrary fluorescent patterns such as a concealed fluorescent QR code can be readily patterned without pre- and/or post-treatment. In addition, the proposed method is applied to the fabrication of fluorescent three-dimensional structures inside a transparent polymer via multiphoton interactions. The proposed method realizes single-stepped and spatially selective patterning of GQDs directly inside polymer substrates and expands the possibilities of GQDs for applications in novel flexible three-dimensional optoelectrical devices.

Microwave two-photon spectroscopy of cesium Rydberg atoms

We present a two-photon microwave spectra of cesium Rydberg atoms in the room-temperature vapor cell. The three-level atom including a ground state 6S1/2 (F = 4), an excited state 6P3/2 (F′ = 5) and Rydberg state consists of Rydberg electromagnetically induced transparency (Rydberg-EIT), that is employed to detect the microwave two-photon spectra. The microwave field with frequency ν DD = 11.42865 GHz couples the transition of Rydberg energy level |68D5/2〉 → |69D5/2〉, measured two-photon spectra display a rich of information including the microwave ac Stark shifts and two-photon Autler-Townes (AT) splitting. In the strong microwave field, the two-photon spectroscopy shows the state mixture between |68D5/2〉 and |68D3/2〉 Stark lines. The microwave two-photon spectra of the |69S1/2〉 → |70S1/2〉 transition coupled with frequency ν SS = 11.73503 GHz are also presented. The Floquet theory is employed to simulate the two-photon microwave spectra, showing the good agreement with the measurements. The work suggests the new method that may be used to investigate the multi-photon field-atom interaction and as an atom-based technique for precision field measurements.

Multiphoton interaction phase shifts in attosecond science

Ab initio simulations of a range of interferometric experiments are used to identify a strong dependence on multiphoton phase shifts in above-threshold ionization. A simple rule of thumb for interaction phase shifts is derived to explain both the conservation of photoelectron yield and its absolute CEP-dependence. For instance, it is found that interferometric above-threshold ionization experiments are shifted by $\pi/4$ relative to RABBIT experiments, and that there is no RABBIT-term in a laser-assisted photoionization experiment with odd and even harmonics. Thus, our work helps to resolve the issues of interpretation of quantum dynamics in attosecond and free-electron laser sciences.

Intensity-dependent and multi-photon Hamiltonian of two two-level atoms and two-mode field in a Kerr medium solved by virtue of supersymmetric unitary transformation

We consider a generalized multi-photon interaction of two collectively two-level atoms with two-mode of electromagnetic field in the presence of Kerr medium and intensity-dependent coupling. We show that this atomic system possesses supersymmetric structure. We solved this system by virtue of supersymmetric unitary transformation. The supersymmetric generators of this atomic system are constructed. The diagonalization of the corresponding Hamiltonian is performed by introducing a supersymmetric unitary transformation. Accordingly, the eigenvalues and eigenfunctions of the Hamiltonian of the atomic system are obtained. The time evolution of the atom–field wave functions is derived in an exact form for two cases of the initial states of the atoms and the field modes. Some quantum effects such as the second-order correlation function, cross-correlation, purity and Husimi Q-function are investigated. The effects of the Kerr medium, detuning parameter, intensity-dependent coupling and multi-photon transition on the evolution of these quantum effects are examined. We conclude that the supersymmetric unitary transformation method is very simple and can be applied to a variety of atomic systems which possess a supersymmetric structure.

On the extreme nonlinear optics of graphene nanoribbons in the strong coherent radiation fields

The generation of high-order harmonics in quasi-one-dimensional graphene nanoribbons (GNRs) initiated by intense coherent radiation is investigated. A microscopic theory describing the extreme nonlinear optical response of GNRs is developed. The closed set of differential equations for the single-particle density matrix at the GNR-strong laser field multiphoton interaction is solved numerically. The obtained solutions indicate the significance of the bandgap width and Fermi energy level on the high-order harmonic generation process in GNRs.

Enhancing atom-field interaction in the reduced multiphoton Tavis-Cummings model

We propose a scheme to enhance the light-matter coupling in a cavity QED system where two $\mathrm{\ensuremath{\Lambda}}$ atoms are weakly coupled to a single-mode cavity via multiphoton interaction. By introducing a second-order nonlinear (parametric) driving of the cavity, the original $N$-photon exchanges between the atoms, and the cavity can be reduced to either an effective single- or two-photon transition depending on the odevity of $N$, with the effective atom-field interaction strength being significantly enhanced. This results in an $N$-dependent effective coupling strength on top of the exponential enhancement induced only by the parametric driving. As an example, we demonstrate that our proposal can be exploited for the preparation of high-fidelity steady-state entanglement. The proposed scheme could provide a feasible alternative for diverse applications in quantum technologies.

Selective interactions in the quantum Rabi model

We demonstrate the emergence of selective $k$-photon interactions in the strong and ultrastrong coupling regimes of the quantum Rabi model with a Stark coupling term. In particular, we show that the interplay between the rotating and counter-rotating terms produces multi-photon interactions whose resonance frequencies depend, due to the Stark term, on the state of the bosonic mode. We develop an analytical framework to explain these $k$-photon interactions by using time-dependent perturbation theory. Finally, we propose a method to achieve the quantum simulation of the quantum Rabi model with a Stark term by using the internal and vibrational degrees of freedom of a trapped ion, and demonstrate its performance with numerical simulations considering realistic physical parameters.

Off-Resonance Control and All-Optical Switching: Expanded Dimensions in Nonlinear Optics

The theory of non-resonant optical processes with intrinsic optical nonlinearity, such as harmonic generation, has been widely understood since the advent of the laser. In general, such effects involve multiphoton interactions that change the population of each input optical mode or modes. However, nonlinear effects can also arise through the input of an off-resonant laser beam that itself emerges unchanged. Many such effects have been largely overlooked. Using a quantum electrodynamical framework, this review provides detail on such optically nonlinear mechanisms that allow for a controlled increase or decrease in the intensity of linear absorption and fluorescence and in the efficiency of resonance energy transfer. The rate modifications responsible for these effects were achieved by the simultaneous application of an off-resonant beam with a moderate intensity, acting in a sense as an optical catalyst, conferring a new dimension of optical nonlinearity upon photoactive materials. It is shown that, in certain configurations, these mechanisms provide the basis for all-optical switching, i.e., the control of light-by-light, including an optical transistor scheme. The conclusion outlines other recently proposed all-optical switching systems.

Spin-Boson Model as A Simulator of Non-Markovian Multiphoton Jaynes-Cummings Models

The paradigmatic spin-boson model considers a spin degree of freedom interacting with an environment typically constituted by a continuum of bosonic modes. This ubiquitous model is of relevance in a number of physical systems where, in general, one has neither control over the bosonic modes, nor the ability to tune distinct interaction mechanisms. Despite this apparent lack of control, we present a suitable transformation that approximately maps the spin-boson dynamics into that of a tunable multiphoton Jaynes-Cummings model undergoing dissipation. Interestingly, the latter model describes the coherent interaction between a spin and a single bosonic mode via the simultaneous exchange of n bosons per spin excitation. Resorting to the so-called reaction coordinate method, we identify a relevant collective bosonic mode in the environment, which is then used to generate multiphoton interactions following the proposed theoretical framework. Moreover, we show that spin-boson models featuring structured environments can lead to non-Markovian multiphoton Jaynes-Cummings dynamics. We discuss the validity of the proposed method depending on the parameters and analyse its performance, which is supported by numerical simulations. In this manner, the spin-boson model serves as a good analogue quantum simulator for the inspection and realization of multiphoton Jaynes-Cummings models, as well as the interplay of non-Markovian effects and, thus, as a simulator of light-matter systems with tunable interaction mechanisms.

Ablation of silicon and ultrathin fibers using single femtosecond pulse

We exploit the nonlinear multiphoton interaction of a few-cycle femtosecond (fs) pulse with viscoelastic microfibers in order to produce nanoscale grooves on its surface. The single fs pulse has been extracted from 1 kHz pulse train by double-shutter gating technique by placing two mechanical shutters in the beamline and simultaneously triggering them with a controlled delay. With adjustment of the time delay between two shutters, a small transmission window has been created to cleanly extract a single or desired number of pulses. We found that the single-pulse ablation threshold for microfiber is $$1 \hbox { J}/\hbox {cm }^2$$ while for absorbing surfaces like crystalline Si is $$0.01 \hbox { J}/\hbox {cm}^2$$. Precise diffraction unlimited ablation of materials opens a route to process nanoscale waveguides, microfluidic devices to isolate cells or macro-molecules.

Atom‐Interferometry Measurement of the Fine Structure Constant

AbstractUsing an atom interferometer to measure the quotient of the reduced Planck's constant and the mass of a cesium‐133 atom , the most accurate measurement of the fine structure constant is recorded, at an accuracy of 0.20 parts per billion (ppb). Using multiphoton interactions (Bragg diffraction and Bloch oscillations), the largest phase (12 million radians) of any Ramsey–Bordé interferometer and controlled systematic effects at a level of 0.12 ppb are demonstrated. Comparing the Penning trap measurements with the Standard Model prediction of the electron gyromagnetic anomaly based on the α measurement, a 2.5 tension is observed, rejecting dark photons as the reason for the unexplained part of the muon's gyromagnetic moment discrepancy at a 99% confidence level according to frequentist statistics. Implications for dark‐sector candidates (e.g., scalar and pseudoscalar bosons, vector bosons, and axial‐vector bosons) may be a sign of physics beyond the Standard Model. A future upgrade of the cesium fountain atom interferometer is also proposed to increase the accuracy of by 1 to 2 orders of magnitude, which would help resolve the tension.

Multiphoton excitation and high-harmonics generation in topological insulator

Multiphoton interaction of coherent electromagnetic radiation with 2D metallic carriers confined on the surface of the 3D topological insulator is considered. A microscopic theory describing the nonlinear interaction of a strong wave and metallic carriers with many-body Coulomb interaction is developed. The set of integrodifferential equations for the interband polarization and carrier occupation distribution is solved numerically. Multiphoton excitation of Fermi–Dirac sea of 2D massless carriers is considered for a THz pump wave. It is shown that in the moderately strong pump wave field along with multiphoton interband/intraband transitions the intense radiation of high harmonics takes place.