Atomic Waveguide Research Articles

The Single-Photon Scattering Properties of Three-Level Giant Atoms under the Interaction of Dissipation and Local Coupling

The coupling of three-level giant atoms with one-dimensional waveguides can show interesting phenomena of transmission and reflection. Since the non-waveguide mode can cause the dissipation of external atoms, we consider the effect of the dissipation rate on the scattering of single photons in the system with giant atom–waveguide coupling. We find that as the dissipation rate of giant atoms increases, the transmission rate of a single photon increases and the reflection rate decreases. In addition, by varying the phase difference and decay rate, the giant atoms are able to achieve perfect transmission and total reflection over the entire frequency range. We also find and show the conditions for the conversion of the optimal frequency. When the cumulative phase of photons reaches a certain value, the system can achieve perfect transmission, which is independent of frequency. This model of coupling giant atoms with waveguides has a promising application in quantum communication and quantum information processing.

Optical Coupling in Atomic Waveguide for Vertically Integrated Photonics.

Integrated 2-dimensional (2D) photonic devices such as monolayer waveguide has generated exceptional interest because of their ultimate thinness. In particular, they potentially permit stereo photonic architecture through bond-free van der Waals integration. However, little is known about the coupling and controlling of the single-atom guided wave to its photonic environment, which governs the design and application of integrated system. Here, we report the optical coupling of atomically guided waves to other photonic modes. We directly probe the mode beating between evanescent waves in a monolayer 2D waveguide and a silicon photonic waveguide, which constitutes a vertically integrated interferometer. The mode-coupling measures the dispersion relation of the guided wave inside the atomic waveguide and unveils it strongly modifies matter's electronic states, manifesting by the formation of a propagating polariton. We also demonstrated light modulating and spectral detecting in this compact nonplanar interferometer. These findings provide a generalizable and versatile platform toward monolithic 3-dimensional integrated photonics.

Distant entanglement generation and controllable information transfer via magnon–waveguide systems

The generation of entanglement and information distribution among macroscopic systems which are spatially separated are of paramount importance in the realm of quantum networks and quantum communication. In this paper, we propose a scheme that enables the preparation of long-distance entanglement between two magnons and controllable information transfer from a giant atom to either magnon, where the two magnons can be positioned symmetrically or asymmetrically in relation to a giant atom, and all of the magnons and the atom are coupled to a microwave cavity-array waveguide. By considering significant frequency detuning, we can virtually excite photons and establish an indirect interaction between the giant atom and the two magnons. Through the modulation of atom–waveguide coupling rates, we can not only evenly transfer atomic excitation to both magnons, thereby generating maximally entangled states, but also selectively transmit the atomic state to a single magnon. It is our hope that our proposed scheme will prove valuable in the field of quantum communications.

Microwave spectroscopy of positronium atoms in free space

We report measurements of the positronium (Ps) $2^{3}S_{1}\ensuremath{\rightarrow}2^{3}P_{2}$ interval in which atoms traveling in free space were irradiated with microwave radiation generated using a horn antenna. Previous measurements of this transition, performed using atoms in waveguides, exhibited asymmetric and shifted line shapes. In the free-space measurements we report here, much smaller line-shape asymmetry was observed, but with large frequency shifts that varied with the orientation of the horn antenna. Our observations are supported by line-shape simulations and demonstrate that variations in the microwave radiation field distribution can perturb measured line shapes and give rise to apparent frequency shifts without necessarily causing large asymmetries; this effect can explain previous measurements in which an apparent discrepancy with predictions from quantum electrodynamics was ob- served [L. Gurung, T. J. Babij, S. D. Hogan, and D. B. Cassidy, Phys. Rev. Lett. 125, 073002 (2020)].

Optical multi-Fano-like phenomena with giant atom–waveguide systems

Optical multi-Fano-like phenomena with giant atom–waveguide systems

Ultrabright and narrowband intra-fiber biphoton source at ultralow pump power

Nonclassical photon sources of high brightness are key components of quantum communication technologies. We here demonstrate the generation of narrowband, nonclassical photon pairs by employing spontaneous four-wave mixing in an optically-dense ensemble of cold atoms within a hollow-core fiber. The brightness of our source approaches the limit of achievable generated spectral brightness at which successive photon pairs start to overlap in time. For a generated spectral brightness per pump power of up to 2 × 109 pairs/(s MHz mW) we observe nonclassical correlations at pump powers below 100 nW and a narrow bandwidth of 2π × 6.5 MHz. In this regime we demonstrate that our source can be used as a heralded single-photon source. By further increasing the brightness we enter the regime where successive photon pairs start to overlap in time and the cross-correlation approaches a limit corresponding to thermal statistics. Our approach of combining the advantages of atomic ensembles and waveguide environments is an important step toward photonic quantum networks of ensemble-based elements.

Superior dark-state cooling via nonreciprocal couplings in trapped atoms

Cooling the trapped atoms toward their motional ground states is key to applications of quantum simulation and quantum computation. By utilizing nonreciprocal couplings between two atoms, we present an intriguing dark-state cooling scheme in Λ-type three-level structure, which is shown superior than the conventional electromagnetically-induced-transparency cooling in a single atom. The effective nonreciprocal couplings can be facilitated either by an atom–waveguide interface or a free-space photonic quantum link. By tailoring system parameters allowed in dark-state cooling, we identify the parameter regions of better cooling performance with an enhanced cooling rate. We further demonstrate a mapping to the dark-state sideband cooling under asymmetric laser driving fields, which shows a distinct heat transfer and promises an outperforming dark-state sideband cooling assisted by collective spin–exchange interactions.

Atomic-Void van der Waals Channel Waveguides

Layered van der Waals materials allow creating unique atomic-void channels with subnanometer dimensions. Coupling light into these channels may further advance sensing, quantum information, and single molecule chemistries. Here, we examine theoretically limits of light guiding in atomic-void channels and show that van der Waals materials exhibiting strong resonances, excitonic and polaritonic, are ideally suited for deeply subwavelength light guiding. We predict that excitonic transition metal dichalcogenides can squeeze >70% of optical power in just <λ/100 thick channel in the visible and near-infrared. We also show that polariton resonances of hexagonal boron nitride allow deeply subwavelength (<λ/500) guiding in the mid-infrared. We further reveal effects of natural material anisotropy and discuss the influence of losses. Such van der Waals channel waveguides while offering extreme optical confinement exhibit significantly lower loss compared to plasmonic counterparts, thus paving the way to low-loss and deeply subwavelength optics.

Directional transport along an atomic chain

Motivated by a recent prediction to engineer the dispersion relation of a waveguide constructed from atomic components [arXiv:2104.08121], we explore the possibility to create directional transport in an open, collective quantum system. The optical response of the atomic waveguide is characterized through a scattering-matrix formalism built upon theories of photoelectric detection that allows us to find the required conditions for directional mode-to-mode transmission to occur and be measured in an experimental setting. We find that directional waveguides allow for an efficient outcoupling of light by reducing backscattering channels at the edges. This reduced backscattering is seen to play a major role on the dynamics when disorder is included numerically. A directional waveguide is shown to be more robust to localization, but at the cost of increased radiative losses.

Nanoscale atomic suspended waveguides for improved vapour coherence times and optical frequency referencing

Nanoscale atomic suspended waveguides for improved vapour coherence times and optical frequency referencing

Crossover from a delocalized to localized atomic excitation in an atom–waveguide interface

An atom–waveguide system, which presents one of the quantum interfaces that enable strong couplings between light and atoms, can support tightly-confined guided modes of light. In this distinctive quantum interface, we theoretically investigate the crossover from a delocalized to localized atomic excitation under long-range dipole–dipole interactions and lattice disorders. Both localization lengths of the excitation distributions and power-law scalings of dissipative von Neumann entanglement entropy show signatures of this crossover. We further calculate numerically the level statistics of the underlying non-Hermitian Hamiltonian, from which as the disorder strength increases, the gap ratio decreases and the intrasample variance increases before reaching respective saturated values. The mean gap ratio in the deeply localized regime is close to the one from Poisson statistics along with a relatively large intrasample variance, whereas in the nondisordered regime, a significant level repulsion emerges. Our results provide insights to study the non-ergodic phenomenon in an atom–waveguide interface, which can be potentially applied to photon storage in this interface under dissipations.

Atom–Photon Interactions in Atomic Cladded Waveguides: Bridging Atomic and Telecom Technologies

Accurate and stable frequency sources can be realized by locking lasers to well-known transitions between energy levels in isolated quantum systems such as alkali atoms. Unfortunately, current impl...

Atomic-waveguide quantum electrodynamics

Atom arrays are a new type of quantum light-matter interface. Here, we propose to employ one-dimensional ordered arrays as atomic waveguides. These arrays support optical guided modes that do not decay into free space. We show that these modes can be harnessed to mediate tunable, long-range interactions between additional "impurity qubits" coupled to the chain, without need for photonic structures. The efficient coupling between qubits and atomic waveguides enables the realization of tunable qubit-qubit interactions, which can be short- or long-range, dissipative or coherent, as well as chiral. Moreover, owing to the two-level nature of atoms, these waveguides are intrinsically quantum. In contrast to classical waveguides, where photons do not interact with each other, atomic waveguides display strong non-linearities, which create a tunable dissipative channel for qubit-qubit interactions, and opens the door to the exploration of many-body physics between guided photons. This physics is universal as it only relies on photon interference and can also be observed with other types of quantum emitters, such as those in molecular or solid-state systems.

Towards all-optical atom chips based on optical waveguides

Coherent guiding of atoms in two-colour evanescent light fields of two fundamental modes of suspended optical rib waveguides is investigated theoretically. Special attention is paid to waveguides of widths larger than the wavelength of light, which provide better lateral stability of the surface traps and waveguides, and can be used in coherent Bragg beam splitters for matter waves, based on optical gratings formed by interference of evanescent light waves of two crossed optical waveguides. A single-mode regime for evanescent-wave waveguides for atoms is investigated. The general structure and key elements of all-optical atom chips are discussed.

Controlled Multichannel Surface Plasmon Polaritons Transmission on Atomic Smooth Silver Triangular Waveguide

AbstractThe application of plasmonic devices is considered as one promising solution for overcoming the limitation of traditional electronic devices. The critical challenges of plasmonic transmission devices include the control accuracy of large‐scale signal transmission and energy loss reduction. The 2D plasmonic waveguide provides a good platform on surface plasmon polaritons (SPPs) multimode excitation and emission manipulation. Here, an atomic smooth triangular waveguide with controllable multichannel transmission and relative long 1/e decay length is demonstrated. Corresponding SPPs excitation and propagation process are investigated through far‐field and near‐field distributions both experimentally and numerically. It is found that two different SPPs propagation modes can be selectively excited and supported on the surface of the 2D waveguide, and the propagation path can be controlled by the interference of the SPPs modes. The collimated beams with tunable period are also achieved on this waveguide via utilizing the interference between the reflected SPPs and the SPPs propagating from the other side of the plate through the edge. This work provides high‐performance 2D plasmonic waveguides with a comprehensive analysis of surface plasmon, which may have potential applications in 2D microplate‐based integrated photonic devices.

Energy-Dependent Three-Body Loss in 1D Bose Gases.

We study the loss of atoms in quantum Newton's cradles with a range of average energies and transverse confinements. We find that the three-body collision rate in one-dimension is strongly energy dependent, as predicted by a strictly 1D theory. We adapt the theory to atoms in waveguides, then, using detailed momentum measurements to infer all the collisions that occur, we compare the observed loss to the adapted theory and find that they agree well.

Pure confinement-induced trimer in one-dimensional atomic waveguides

Shallow trimers composed of three bosonic atoms in one-dimensional harmonic waveguides are studied in the vicinity of a Feshbach resonance. It is shown that for arbitrarily large values of the one-dimensional scattering length, an excited trimer branch exists in coexistence with the dimer and the trimer of the Lieb-Liniger model.

Kerr-field-induced tunable optical atomic waveguide

We propose an efficient scheme for the generation of tunable optical waveguide based on atomic vapor in N -type configuration. We exploit both control field induced transparency and Kerr field induced absorption to produce a flexible probe transparency window otherwise not feasible. We employ a suitable spatial profile of control and Kerr beams to create a high contrast refractive in- dex modulation that holds the key to guiding a weak narrow probe beam. Further we numerically demonstrate that high contrast tunable waveguide permits the propagation of different modes of probe beam to several Rayleigh lengths without diffraction. This efficient guiding of narrow opti- cal beam may have important applications in large density image processing, and high resolution imaging.

Tunable axial potentials for atom-chip waveguides

We present a method for generating precise magnetic potentials that can be described by a polynomial series along the axis of a cold atom waveguide near the surface of an atom chip. With a single chip design consisting of several wire pairs, various axial potentials can be created by varying the ratio of the currents in the wires, including double wells, triple wells, and pure harmonic traps with suppression of higher order terms. We use this method to design and fabricate a chip with modest experimental requirements. Finally, we use the chip to demonstrate a double well potential.

On-chip quantum tomography of mechanical nanoscale oscillators with guided Rydberg atoms

Nano-mechanical oscillators as well as Rydberg-atomic waveguides hosted on micro-fabricated chip surfaces hold promise to become pillars of future quantum technologies. In a hybrid platform with both, we show that beams of Rydberg atoms in waveguides can quantum-coherently interrogate and manipulate nanomechanical elements, allowing full quantum state tomography. Central to the tomography are quantum non-demolition measurements using the Rydberg atoms as probes. Quantum coherent displacement of the oscillator is also made possible, by driving the atoms with external fields while they interact with the oscillator. We numerically demonstrate the feasibility of this fully integrated on-chip control and read-out suite for quantum nano-mechanics, taking into account noise and error sources.