Matter-wave Interference Research Articles

Determination of principal axes orientation in an ion trap using matter-wave interference

We have developed a method for determining the orientations of the principal axes of an ion trap using an ion matter-wave interferometer. By examining the ion matter-wave interference signal induced by spin-dependent momentum kicks originating from stimulated Raman transitions, we can accurately ascertain the angles between the directions of these momentum kicks and the trap principal axes. The application of direct–current voltage to the ground electrodes, a common method adopted to finely tune trap frequencies in ion traps, leads to the trap principal axes rotating, a phenomenon that is yet to be reported quantatively. Our measurements successfully captured the rotation of the trap axes depending on the applied offset voltages. The findings of this study offer valuable insights into the functioning of ion traps for diverse quantum science and technology applications.

Gravitationally induced entanglement in a harmonic trap

Recent work has shown that it may be possible to detect gravitationally induced entanglement in tabletop experiments in the not-too-distant future. However, there are at present no thoroughly developed models for this type of experiment where the entangled particles are treated more fundamentally as excitations of a relativistic quantum field, and with the measurements modeled using expectation values of field observables. Here we propose a thought experiment where two particles are initially prepared in a superposition of coherent states within a common three-dimensional (3D) harmonic trap. The particles then develop entanglement through their mutual gravitational interaction, which can be probed through particle position detection probabilities. The present work gives a nonrelativistic quantum mechanical analysis of the gravitationally induced entanglement of this system, which we term the ``gravitational harmonium'' due to its similarity to the harmonium model of approximate electron interactions in a helium atom; the entanglement is operationally determined through the matter wave interference visibility. The present work serves as the basis for a subsequent investigation, which models this system using quantum field theory, providing further insights into the quantum nature of gravitationally induced entanglement through relativistic corrections, together with an operational procedure to quantify the entanglement.

An apparatus for in-vacuum loading of nanoparticles into an optical trap.

We describe the design, construction, and operation of an apparatus that utilizes a piezoelectric transducer for in-vacuum loading of nanoparticles into an optical trap for use in levitated optomechanics experiments. In contrast to commonly used nebulizer-based trap-loading methods that generate aerosolized liquid droplets containing nanoparticles, the method produces dry aerosols of both spherical and high-aspect ratio particles ranging in size by approximately two orders of magnitude. The device has been shown to generate accelerations of order 107g, which is sufficient to overcome stiction forces between glass nanoparticles and a glass substrate for particles as small as 170nm in diameter. Particles with sizes ranging from 170nm to ∼10μm have been successfully loaded into optical traps at pressures ranging from 1bar to 0.6mbar. We report the velocity distribution of the particles launched from the substrate, and our results indicate promise for direct loading into ultra-high-vacuum with sufficient laser feedback cooling. This loading technique could be useful for the development of compact fieldable sensors based on optically levitated nanoparticles as well as matter-wave interference experiments with ultra-cold nano-objects, which rely on multiple repeated free-fall measurements and thus require rapid trap re-loading in high vacuum conditions.

Nanoscale Magnetism Probed in a Matter-Wave Interferometer.

We explore a wide range of fundamental magnetic phenomena by measuring the dephasing of matter-wave interference fringes upon application of a variable magnetic gradient. The versatility of our interferometric Stern-Gerlach technique enables us to study the magnetic properties of alkali atoms, organic radicals, and fullerenes in the same device, with magnetic moments ranging from a Bohr magneton to less than a nuclear magneton. We find evidence for magnetization of a supersonic beam of organic radicals and, most notably, observe a strong magnetic response of a thermal C_{60} beam consistent with high-temperature atomlike deflection of rotational magnetic moments.

Interference fringe fitting of atom gravimeter based on fitness particle swarm optimization

In the atom gravimeter, three Raman pulses are utilized to realize the interference of atom matter waves, and atom interference fringes are obtained by scanning the chirp rate of the Raman laser during the interference time. Previously, fringe data analysis methods used LS (Least Squares) to fit the cosine function of each interference fringe data to minimize the standard deviation between the estimated value and the observed value of each group of fringe data or the EKF (Extended Kalman Filter) method to obtain the estimation of the gravity value. In this paper, we propose a new method applied to the interference fringe fitting of the atom gravimeter, namely, through the FPSO (Fitness Particle Swarm Optimization) method to estimate the parameters of the interference fringe atom and then estimate the gravity value. First, the theoretical analysis and proof are carried out by using simulation data. On this basis, we carried out a gravity measurement experiment in the ship-mounted mooring state, which further verified the feasibility and effectiveness of the algorithm. The simulation and experimental results show that, compared with LS and EKF methods, the FPSO method can search the relatively optimal fitting parameters of atom interference fringes quickly and accurately and improve the accuracy and stability of the atom gravimeter measurement. It is feasible and effective to apply the FPSO method to fitting atom interference fringes. The FPSO method proposed in this paper can be used as a new method for fitting atom interference fringes, which provides a new idea and choice for accurate gravity measurement in a dynamic environment.

Phase-locking matter-wave interferometer of vortex states

Matter-wave interferometer of ultracold atoms with different linear momenta has been extensively studied in theory and experiment. The vortex matter-wave interferometer with different angular momenta is applicable as a quantum sensor for measuring the magnetic field, rotation, geometric phase, etc. Here we report the experimental realization of a vortex matter-wave interferometer by coherently transferring the optical angular momentum to an ultracold Bose condensate. We use the angular interference technique to measure the relative phase of two vortex states. For a lossless interferometer with atoms only populating two spin states, the difference between the relative phases in the two spin states is locked to π. We also prove the robustness of this out-of-phase relation, not sensitive to the angular-momentum difference between two vortex states, constituent of Raman optical fields and expansion of the condensate. The experimental results agree well with the calculation from the unitary evolution of wave packet in quantum mechanics. This work opens a new way to build a quantum sensor based on the vortex matter-wave interference.

Coherent atomic orbital polarization probes the geometric phase in photodissociation of polyatomic molecules

AbstractQuantum interference between multiple pathways in molecular photodissociation often results in angular momentum polarization of atomic products and this can give deep insight into fundamental physical processes. For dissociation of diatomic molecules, the resulting orbital polarization is fully understood and consistent with quantum mechanical theory. For polyatomic molecules, however, coherent photofragment orbital polarization is frequently observed but so far has eluded theoretical explanation, and physical insight is lacking. Here, we present a model of these effects for ozone photodissociation that reveals the importance of a novel manifestation of the geometric phase. We show this geometric phase effect permits the existence of coherent polarization in cases where it would otherwise vanish, and cancels it in some cases where it might otherwise exist. The model accounts for measurements in ozone that have hitherto defied explanation, and represents a step toward a deeper understanding of coherent electronic excitation in polyatomic molecules and a new role of the geometric phase.Key Points Coherent photofragment atomic orbital polarization reveals matter wave interference in dissociation along multiple paths. In diatomic molecules, this is well‐understood, but in polyatomic molecules, large effects are seen but these have defied a rigorous explanation. A model is developed describing these phenomena in the UV dissociation of ozone that accounts for a number of conflicting observations and reveals a new manifestation of the geometric phase in molecular physics.

A roadmap for universal high-mass matter-wave interferometry

Creating quantum superposition states of bodies with increasing mass and complexity is an exciting and important challenge. Demonstrating such superpositions is vital for understanding how classical observations arise from the underlying quantum physics. Here, we discuss how recent progress in macromolecule interferometry can be combined with the state of the art in cluster physics to push the mass record for matter-wave interference with wide state separation by 3 to 4 orders of magnitude. We show how near-field interferometers in different configurations can achieve this goal for a wide range of particle materials with strongly varying properties. This universality will become important in advanced tests of wave function collapse and of other modifications of quantum mechanics, as well as in the search for light dark matter and in tests of gravity with composite quantum systems.

Using atom interferometry to measure gravity

The interference of matter waves is a direct consequence of wave-particle duality and lies at the heart of quantum mechanics. Today, with the validity of quantum theory being widely ascertained, we are beyond proof-of-principle demonstrations and are transforming this phenomenon into a measurement tool for practical applications via the development of quantum technologies. Atom interferometry is a special type of quantum technology, which is particularly suitable for the detection of gravity. Its potential for absolute, low-drift measurements with options for noise suppression could bring wide-ranging benefits for applications that are important across economies. This journey from the laboratory into the real world of applications requires the understanding and mitigation of the effects of external influences on the system.

Schrödinger cat states of a macroscopic charged particle co-trapped with an ion

We investigate the feasibility of observing matter-wave interference of a micron-sized charged particle by putting it into a quantum superposition of states with a distinguishable separation. In the proposed method, an atomic ion is confined in a linear Paul trap along with the massive charged particle so that we can make use of the extensive toolbox of experimental techniques developed to control quantum states of trapped ions, and to manipulate their motions with high fidelity operations. This approach provides a stringent test of the predictions of dynamical reduction models of delocalised quantum superpositions of a particle, reaching macroscopicities of up to $\mathcal{M}=17$.

Three-Dimensional Matter-Wave Interferometry of a Trapped Single Ion.

We report on a demonstration of Ramsey interferometry by three-dimensional motion with a trapped ^{171}Yb^{+} ion. We applied a momentum kick to the ion in a direction diagonal to the trap axes to initiate three-dimensional motion using a mode-locked pulse laser. The interference signal was analyzed theoretically to demonstrate three-dimensional matter-wave interference. This work paves the way to realizing matter-wave interferometry using trapped ions.

Experimental studies on photoabsorption by endohedral fullerene ions with a focus on Xe@C60 + confinement resonances

A brief overview on the status of experimental investigations into photoionization and fragmentation of fullerenes and endohedral fullerenes by absorption of a single short-wavelength photon is presented. The focus of this paper is on the endohedral Xe@C60 + molecular ion in which a xenon atom is centrally encapsulated inside a fullerene cage. Confinement resonances that result from the interference of Xe photoelectron matter waves emerging from the cavity were studied by exposing Xe@C60 + ions to synchrotron radiation of 60 to 150 eV energy which is the region of the well-known giant atomic Xe excitation resonance. Photoions Xe@C n q+ (with final charge states of the product ions and numbers of carbon atoms left in the cage) were recorded as a function of photon energy and cross sections for the individual reaction channels were determined. In addition to previous work, new final channels ( and ) were observed, and thus, about 70% of the oscillator strength expected for the encapsulated Xe atom in the investigated energy range could be recovered. The present results establish the first and, so far, only conclusive experimental observation of confinement resonances in an endohedral fullerene. The data are in remarkable agreement with relativistic R-matrix calculations that accompanied the previous experimental work.

All possible paths: bringing quantum electrodynamics to classrooms

Quantum electrodynamics was described by Feynman as the ‘jewel of physics’ [1985 QED: The Strange Theory of Light and Matter (Alix G. Mautner Memorial Lectures) (Princeton, NJ: Princeton University Press)] because of its ability to precisely describe the interaction of light and matter. It embodies the key concepts of quantum physics and yet also describes classical optics. It is normally considered to be too advanced for use in schools. Here we show that through the use of novel learning tools called phasor wheels, it is possible to make quantum electrodynamics accessible to students from middle school and higher. Our graphical approach is based on the summation of all possible paths (formally known as Feynman path integrals). It uses graphical vector addition, and gives students a deep understanding of vectors. It offers insights into the quantum world in which observations represent quantum probability density, while correctly describing the laws of classical optics. The phasor wheel is a tactile tool that allows students to compute the probability of photons arriving at a point in space and to explore phenomena such as matter–wave interference, diffraction, and reflection without any distinction between quantum or classical. To make it accessible, we combine the phasor tool with real-life analogies, and videos of single quanta interference. Needing only elementary mathematics, the approach is suitable for middle/upper secondary schools as well early undergraduate students.

Polariton spin jets through optical control

We demonstrate spin polarized jets in extended systems of ballistic exciton-polariton condensates in semiconductor microcavities using optical non-resonant excitation geometries. The structure of the spin jets is determined by the digitally reprogrammable, spatially non-uniform, degree of circular polarization of the excitation laser. The presence of the laser excitation, strong particle interactions, and spin-relaxation leads to a tunable spin-dependent potential landscape for polaritons, with the appearance of intricate polarization patterns due to coherent matter-wave interference. Our work realizes polarization-structured coherent light sources in the absence of gauge fields.

Single-pixel neutron imaging with artificial intelligence: Breaking the barrier in multi-parameter imaging, sensitivity, and spatial resolution

Different from X-rays, neutrons mainly interact with atomic nuclei and magnetic moments in materials. This makes neutron imaging a complementary contrast mechanism to X-ray imaging. Neutron imaging aims to infer the internal material information of the object by measuring the changes in neutron beam parameters, such as the intensity attenuation, polarization, scattering, and matter wave interference. It has a wide range of applications in industry such as the inspection of batteries, magnetic structure analysis, and strain mapping in alloys.

On-demand generation of dark soliton trains in Bose-Einstein condensates

Matter-wave interference mechanisms in one-dimensional Bose-Einstein condensates that allow for the controlled generation of dark soliton trains upon choosing suitable box-type initial configurations are described. First, the direct scattering problem for the defocusing nonlinear Schr\"odinger equation with nonzero boundary conditions and general box-type initial configurations is discussed, and expressions for the discrete spectrum corresponding to the dark soliton excitations generated by the dynamics are obtained. It is found that the size of the initial box directly affects the number, size and velocity of the solitons, while the initial phase determines the parity of the solutions. The analytical results are compared to those of numerical simulations of the Gross-Pitaevskii equation, both in the absence and in the presence of a harmonic trap. The numerical results bear out the analytical results with excellent agreement.

Irrealism from fringe visibility in matter-wave double-slit interference with initial contractive states

The elements of reality coined by Einstein, Podoslky, and Rosen promoted a series of fundamental discussions involving the notion of quantum correlations and physical realism. The superposition principle applied in the double-slit experiment with matter waves highlights the need for a critical review of the adoption of physical realism in the quantum realm. In this work, we employ a measure of physical irrealism and consider an initial contractive state in the double-slit setup for which position and momentum variables of a single particle are initially correlated. We investigate how the behavior of the irrealism can help us to obtain information about the interference pattern, wavelike, and particle-like properties in the double-slit setup with matter waves. We find that there is a time of propagation that minimizes the irrealism, and around this point the state at the detection screen is squeezed in position and momentum in comparison with the standard Gaussian superposition. Interestingly, we show that the maximum visibility and the number of interference fringes are related to the minimum of the irrealism. Moreover, we demonstrate a monotonic relation between the irrealism and visibility around the time of minimum. Then, we argue how to use these results to indirectly measure the irrealism for position variable from the fringe visibility.

Effect of interactions in the interference pattern of Bose-Einstein condensates

Understanding the effect of interactions in the phase evolution of expanding atomic Bose Einstein condensates is fundamental to describe the basic phenomenon of matter wave interference. Many theoretical and experimental works tackled this problem, always with the implicit assumption that the mutual interaction between two expanding condensates rigidly modifies the phase evolution through an effective force. In this paper, we present a combined experimental and theoretical investigation of the interference profile of expanding $^{87}$Rb condensates, with a specific focus on the effect of interactions. We come to the different conclusion that the mutual interaction produces local modifications of the condensate phase only in the region where the wavepackets overlap.

Coherent splitting of two-dimensional Bose gases in magnetic potentials

Investigating out-of-equilibrium dynamics with two-dimensional (2D) systems is of widespread theoretical interest, as these systems are strongly influenced by fluctuations and there exists a superfluid phase transition at a finite temperature. In this work, we realise matter-wave interference for degenerate Bose gases, including the first demonstration of coherent splitting of 2D Bose gases using magnetic trapping potentials. We improve the fringe contrast by imaging only a thin slice of the expanded atom clouds, which will be necessary for subsequent studies on the relaxation of the gas following a quantum quench.

All-order momentum correlations of three ultracold bosonic atoms confined in triple-well traps: Signatures of emergent many-body quantum phase transitions and analogies with three-photon quantum-optics interference

All-order momentum correlation functions associated with the time-of-flight spectroscopy of three spinless ultracold bosonic interacting neutral atoms confined in a linear three-well optical trap are presented. The underlying Hamiltonian employed for the interacting atoms is an augmented three-site Hubbard model. Our investigations target matter-wave interference of massive particles, aiming at the establishment of experimental protocols for characterizing the quantum states of trapped attractively or repulsively interacting ultracold particles, with variable interaction strength. The manifested advantages and deep physical insights that can be gained through the employment of the results of our study for a comprehensive understanding of the nature of the quantum states of interacting many-particle systems, via analysis of the all-order (that is 1st, 2nd and 3rd) momentum correlation functions for three bosonic atoms in a three well confinement, are illustrated and discussed in the context of time-of-flight inteferometric interrogations of the interaction-strength-induced emergent quantum phase transition from the Mott insulating phase to the superfluid one. Furthermore, we discuss that our inteferometric interrogations establish strong analogies with the quantum-optics interference of three photons, including the aspects of genuine three-photon interference, which are focal to explorations targeting the development and implementation of quantum information applications and quantum computing.