Light-Pulsed Atom Interferometry (LPAI)

• LPAI is a technique that employs pulsed light fields to coherently split, redirect, and recombine atomic wave packets, enabling precise measurements of inertial forces.
• It utilizes well-defined pulse sequences, such as Mach–Zehnder and Ramsey schemes, to translate gravitational and inertial effects into measurable phase shifts.
• Advancements in large-momentum-transfer methods and integrated photonic control enhance sensitivity and pave the way for compact, high-precision sensors.

Searching arXiv for recent and foundational work on light-pulse atom interferometry to ground the article. Light-pulsed atom interferometry (LPAI) is a class of matter-wave interferometry in which pulsed light fields coherently split, redirect, and recombine atomic wave packets, typically by Raman, Bragg, Kapitza–Dirac, or single-photon clock transitions. In its standard form, a sequence of laser pulses acts as beam splitters and mirrors for the atomic center-of-mass motion, while simultaneously imprinting laser phases and momentum kicks that map inertial, gravitational, and relativistic effects onto measurable output populations or spatial fringes. Across current implementations, the canonical phase scaling under uniform acceleration is $$\Delta\phi = \mathbf k_{\rm eff}\!\cdot\!\mathbf g\,T^2$$, with $\mathbf k_{\rm eff}$ set by the diffraction mechanism and $T$ the pulse separation time (Hamilton et al., 2014, Hamilton et al., 2013). Contemporary LPAI encompasses large-momentum-transfer (LMT) beam splitters, cavity-enhanced atom optics, point-source and multi-axis interferometers, single-photon clock-transition devices, and formalisms that incorporate gravity gradients, rotations, finite-speed-of-light effects, perturbing potentials, and quantization of the light field itself (Béguin et al., 2023, Kleinert et al., 2015, Niehof et al., 5 May 2025, Asano et al., 2022, Soukup et al., 2021).

1. Operating principle and canonical pulse sequences

LPAI proceeds by manipulating the external and, in many implementations, internal degrees of freedom of atoms with pulsed optical fields. In the standard Mach–Zehnder geometry, a $\pi/2$ pulse creates a coherent superposition of momentum states, a $\pi$ pulse redirects the two branches after a free-evolution interval $T$, and a final $\pi/2$ pulse recombines them after a second interval $T$ (Hamilton et al., 2014, Hamilton et al., 2013). In Raman realizations, the counter-propagating light fields typically impart $\pm 2\hbar k$ momentum transfer and couple two hyperfine ground states; in Bragg implementations, momentum is transferred without changing the internal state; in single-photon clock implementations, each pulse combines an internal-state flip with a recoil $\pm \hbar k$ (Hamilton et al., 2014, Roura, 2024).

For a three-pulse Mach–Zehnder under uniform gravitational acceleration, the leading phase is

$\mathbf k_{\rm eff}$0

or $\mathbf k_{\rm eff}$1 for an $\mathbf k_{\rm eff}$2-photon or multiphoton LMT beam splitter (Hamilton et al., 2014). In a Bragg or Raman gravimeter this phase appears in the population of one output port, while in point-source interferometry it can be spatially resolved across an expanding cloud, allowing simultaneous readout of acceleration and rotation through fringe offsets and gradients (Dickerson et al., 2013).

Beyond the canonical Mach–Zehnder, LPAI includes Ramsey–Raman and Ramsey–Bordé sequences, multi-loop geometries such as butterfly interferometers, and multidimensional pulse networks. In an optical cavity, velocity-insensitive co-propagating Raman $\mathbf k_{\rm eff}$3 pulses realize Ramsey–Raman fringes with period $\mathbf k_{\rm eff}$4, while counter-propagating Raman pulses realize a cavity-based Mach–Zehnder (Hamilton et al., 2014). A four-pulse Ramsey–Bordé interferometer driven by picosecond frequency-comb pulses has also been demonstrated for free-falling $\mathbf k_{\rm eff}$5Rb, where each effective $\mathbf k_{\rm eff}$6 pulse is itself a train of picosecond pulses (Solaro et al., 2022).

A central feature of LPAI is that the pulse sequence determines not only the momentum splitting but also the interferometer geometry in space-time. This suggests treating the device as a programmable sequence of atom-optical elements rather than a single fixed architecture. In large-momentum-transfer Bragg interferometry, for example, a beam splitter may be implemented as $\mathbf k_{\rm eff}$7, followed by a mirror $\mathbf k_{\rm eff}$8, and a final $\mathbf k_{\rm eff}$9, thereby scaling the effective splitting to $T$0 (Béguin et al., 2023).

2. Atom optics, interaction Hamiltonians, and momentum transfer

The atom-optical element in LPAI is generated by the light–matter interaction Hamiltonian. In quasi-Bragg diffraction, each pulse can be modeled as an effective two-level system coupling $T$1, with instantaneous Hamiltonian

$T$2

where $T$3 is the two-photon Rabi frequency, $T$4 the optical phase, and $T$5 the Bragg detuning (Béguin et al., 2023). A resonant $T$6-pulse then acts as a unitary transfer between adjacent momentum states differing by $T$7 (Béguin et al., 2023).

For cavity Raman interferometry, the effective two-photon Rabi frequency is

$T$8

and the intracavity field enhancement scales as $T$9, so that $\pi/2$0 and $\pi/2$1 (Hamilton et al., 2014). In the demonstrated cavity geometry, a finesse $\pi/2$2 and $\pi/2$3 waist provide power enhancement, spatial filtering, and precise beam geometry (Hamilton et al., 2014).

Single-photon clock-transition LPAI uses a distinct atom-optical mechanism. A $\pi/2$4 pulse on a clock transition transforms

$\pi/2$5

followed at time $\pi/2$6 by a $\pi/2$7 pulse that exchanges $\pi/2$8 and $\pi/2$9, and a final $\pi$0 pulse at $\pi$1 (Roura, 2024). Because the states are a true clock pair, this platform directly links internal-state evolution and center-of-mass dynamics.

Other diffraction mechanisms extend the atom-optics repertoire. The Born-rule proposal based on a Bose–Einstein condensate uses double-Bragg diffraction to generate a three-path superposition $\pi$2, while single-photon Raman transitions act as selective path-blocking masks (Kanthak et al., 2024). A polarimetric interferometer proposal replaces fluorescence counting by polarization spectroscopy after Kapitza–Dirac diffraction on a two-level condensate (Muradyan, 20 Jun 2025). The antimatter gravimetry proposal employs far-off-resonant Bragg diffraction to avoid resonant lasers and to accommodate species-agnostic operation, including antihydrogen (Hamilton et al., 2013).

The effective wave vector $\pi$3 is itself a nontrivial quantity. In Raman and Bragg devices it is usually approximated by the wave-vector difference or sum of the optical fields, but several works show corrections from beam geometry, gravity, finite light speed, and the transverse confinement imposed by the atomic wave function. A Gaussian atomic transverse profile can project the photon’s transverse state and produce a shift $\pi$4, yielding systematic phase biases in high-precision LPAI (Sun et al., 2018). Likewise, in weak gravity the optical phase satisfies an eikonal equation leading to a position-dependent redshift of the wave vector, and modified momentum transfer contributes to the interferometer phase (Pumpo et al., 2022).

3. Phase, contrast, and general theoretical descriptions

Although $\pi$5 is the canonical result, modern LPAI theory treats phase and visibility in more general operator and phase-space form. A representation-free description models pulses as generalized beam splitters acting on phase-space operators $\pi$6, with arbitrary quadratic Hamiltonians and symplectic propagation between pulses (Kleinert et al., 2015). For an $\pi$7-pulse geometry, the interferometric phase can be written as

$\pi$8

and expanded to include local acceleration $\pi$9, gravity-gradient tensor $T$0, and rotation $T$1 (Kleinert et al., 2015). For a Mach–Zehnder, this recovers the standard acceleration term together with gradient and rotation corrections; for butterfly and higher-loop interferometers, lower-order contributions can be canceled by design (Kleinert et al., 2015).

A complementary perturbative operator approach treats the branch overlap operator $T$2 via Magnus and cumulant expansions. For a closed-path interferometer with small perturbing potential $T$3, the phase up to second order is

$T$4

where the second term is the leading wave-packet correction from the curvature of the perturbing potential (Ufrecht et al., 2020). The corresponding contrast is governed by the centered second cumulant,

$T$5

showing explicitly how spatially varying perturbations reduce visibility even when the mean trajectory remains closed (Ufrecht et al., 2020).

These formal tools have direct experimental relevance. Magnetic-field gradients, black-body-radiation shifts, self-gravity, gravity gradients, and wave-packet expansion can all induce measurable phase and contrast changes in precision LPAI (Ufrecht et al., 2020). In a worked Mach–Zehnder example with homogeneous magnetic-field gradient $T$6, the leading phase shift is $T$7, while the wave-packet curvature term vanishes because $T$8 (Ufrecht et al., 2020).

Several specialized phase mechanisms have also been analyzed. In a four-pulse Ramsey–Bordé Raman interferometer, Morel et al. identify a velocity-dependent phase shift arising from wave-packet displacement during light pulses combined with time-varying laser intensity across Gaussian Raman beams (Morel et al., 2020). For small linear Rabi-frequency drift $T$9, the residual phase scales as $\pi/2$0, and can reach tens of mrad under realistic conditions (Morel et al., 2020). In the reported experiment, a dispersive phase curve of amplitude $\pi/2$1 mrad was observed and then mitigated by laser-power ramps (Morel et al., 2020).

This accumulation of theory clarifies a common misconception: the phase is not determined solely by the classical action along ideal trajectories. Laser phases, momentum-transfer corrections, finite-duration pulse effects, wave-packet structure, and imperfect closure all enter at the precision frontier. The formalism of LPAI has therefore expanded from textbook three-pulse models to full operator-level treatments that preserve phase-space closure, visibility, and systematics on equal footing (Kleinert et al., 2015, Ufrecht et al., 2020).

4. Large-momentum transfer and coherent enhancement

Large-momentum-transfer atom optics is a principal route to increasing LPAI sensitivity because the interferometric phase scales with $\pi/2$2. A notable recent development is the realization of LMT interferometers using sequential quasi-Bragg pulses with coherent enhancement of Bragg pulse sequences (CEBS) (Béguin et al., 2023). In this approach, a $\pi/2$3 beam-splitter sequence imparts a net kick $\pi/2$4, and the full Mach–Zehnder reaches total splitting $\pi/2$5 (Béguin et al., 2023).

The key mechanism is destructive interference of non-adiabatic loss channels from successive diabatic pulses. For short interpulse separation $\pi/2$6, two dominant amplitudes feeding a nearby loss state interfere as

$\pi/2$7

which is strongly suppressed for $\pi/2$8 (Béguin et al., 2023). Experimentally, a numerical model including higher-order paths, finite temperature, and pulse-to-pulse amplitude fluctuations fits the measured per-pulse efficiency and yields an asymptotic $\pi/2$9; without interference, the predicted efficiency would be far lower (Béguin et al., 2023).

The reported implementation used a $T$0Rb BEC with $T$1, one-photon detuning $T$2, pulse duration $T$3, and peak Rabi frequency $T$4 (Béguin et al., 2023). Momentum splitting up to $T$5 was demonstrated at $T$6, described as the largest so far with sequential quasi-Bragg pulses (Béguin et al., 2023). For splittings $T$7, operation at $T$8 preserved visibility at $T$9–$\pm 2\hbar k$0 out to $\pm 2\hbar k$1, with detected atoms at $\pm 2\hbar k$2 of the initial population; an example fringe at $\pm 2\hbar k$3 had $\pm 2\hbar k$4 (Béguin et al., 2023).

The same work characterizes parasitic interferometers generated by the multi-port structure of quasi-Bragg pulses. Residual population in neighboring momentum orders can form closed or open unwanted loops that also respond to a scanned lattice phase, thereby biasing visibility when their path separation remains within the coherence length (Béguin et al., 2023). The measured visibility as a function of $\pm 2\hbar k$5 for small $\pm 2\hbar k$6 was fitted to

$\pm 2\hbar k$7

from which a damping time $\pm 2\hbar k$8 was extracted (Béguin et al., 2023). Since path separation grows with $\pm 2\hbar k$9, parasitic loops are suppressed for $\pm \hbar k$0 even as $\pm \hbar k$1 (Béguin et al., 2023).

The total space-time area of the LMT interferometer relative to the three-pulse baseline obeys

$\pm \hbar k$2

so short $\pm \hbar k$3 and $\pm \hbar k$4 maximize net gain per pulse (Béguin et al., 2023). The authors explicitly state that with $\pm \hbar k$5 they foresee sub-ms $\pm \hbar k$6 beam splitters, and numerical simulations in the CEBS regime suggest a path toward $\pm \hbar k$7 provided $\pm \hbar k$8 and $\pm \hbar k$9 (Béguin et al., 2023).

This suggests that the traditional compromise between adiabatic, velocity-selective pulses and high-bandwidth short pulses can be partially relaxed when successive loss channels interfere destructively. The significance is not merely larger momentum splitting, but a revised design principle for LMT atom optics in which diabaticity is exploited rather than simply tolerated (Béguin et al., 2023).

5. Experimental platforms and architectures

LPAI has diversified into a broad set of experimental architectures, each emphasizing a different combination of power handling, compactness, species compatibility, baseline, readout strategy, and systematic suppression.

An optical-cavity architecture uses intracavity Raman pulses as beam splitters and mirrors. The cavity provides power enhancement, spatial filtering, and precise beam geometry, enabling low-power beam splitters $\mathbf k_{\rm eff}$00, large-momentum-transfer beam splitters with modest power, and self-aligned interferometer geometries using transverse cavity modes (Hamilton et al., 2014). In the demonstrated cesium system, the cavity length was $\mathbf k_{\rm eff}$01, the finesse $\mathbf k_{\rm eff}$02, the linewidth $\mathbf k_{\rm eff}$03, and up to $\mathbf k_{\rm eff}$04 atoms were loaded into the intracavity lattice, with $\mathbf k_{\rm eff}$05 participating in the interferometer (Hamilton et al., 2014). Ramsey–Raman contrast exceeded $\mathbf k_{\rm eff}$06, Mach–Zehnder contrast at $\mathbf k_{\rm eff}$07 was $\mathbf k_{\rm eff}$08, and the gravity sensitivity reached $\mathbf k_{\rm eff}$09 at $\mathbf k_{\rm eff}$10 (Hamilton et al., 2014).

Long-baseline point-source interferometry extends interrogation time and enables multi-axis inertial sensing by mapping initial velocity onto final position through ballistic expansion. In the Stanford 10 m tower experiment, a three-pulse Raman interferometer on free-falling $\mathbf k_{\rm eff}$11Rb achieved $\mathbf k_{\rm eff}$12, wave-packet separation $\mathbf k_{\rm eff}$13, inferred per-shot acceleration sensitivity $\mathbf k_{\rm eff}$14, and Earth-rotation measurement with $\mathbf k_{\rm eff}$15 precision (Dickerson et al., 2013). Here the spatial phase gradient across the cloud encodes two orthogonal rotation components, while the mean phase gives the acceleration along $\mathbf k_{\rm eff}$16 (Dickerson et al., 2013).

Multidimensional atom optics push this idea further by creating simultaneous coherent superpositions along three spatial axes. Orthogonal Raman pairs define a four-level effective dynamics in which a 3D $\mathbf k_{\rm eff}$17 pulse diffracts $\mathbf k_{\rm eff}$18 into equal-amplitude superpositions along $\mathbf k_{\rm eff}$19, $\mathbf k_{\rm eff}$20, and $\mathbf k_{\rm eff}$21, and a 3D interferometer yields simultaneous 2D Mach–Zehnder loops in the $\mathbf k_{\rm eff}$22, $\mathbf k_{\rm eff}$23, and $\mathbf k_{\rm eff}$24 planes (Barrett et al., 2019). The derived phase

$\mathbf k_{\rm eff}$25

makes explicit how one-shot measurement of the full acceleration and rotation vectors can be constructed by suitable linear combinations of area-reversed interferometers (Barrett et al., 2019).

Frequency-comb-driven LPAI constitutes another distinct platform. In the demonstrated system, two counter-propagating trains of picosecond pulses drive stimulated Raman transitions between the $\mathbf k_{\rm eff}$26Rb hyperfine states, with central wavelength $\mathbf k_{\rm eff}$27, detuning $\mathbf k_{\rm eff}$28, repetition rate $\mathbf k_{\rm eff}$29, and pulse duration $\mathbf k_{\rm eff}$30–$\mathbf k_{\rm eff}$31 (Solaro et al., 2022). Clear Ramsey–Bordé fringes with $\mathbf k_{\rm eff}$32 contrast were observed at $\mathbf k_{\rm eff}$33, and the contrast dependence on pulse length and interrogation time was reproduced by a numerical model based on the overlap of the pulse trains with the atomic cloud (Solaro et al., 2022).

Integrated photonic control has also entered the field. A silicon-photonic suppressed-carrier single-sideband modulator at $\mathbf k_{\rm eff}$34 has been used to generate the laser frequencies required for cold-atom preparation, state-selective detection, and Raman interferometry in $\mathbf k_{\rm eff}$35Rb (Kodigala et al., 2022). Reported performance includes $\mathbf k_{\rm eff}$36 carrier suppression, $\mathbf k_{\rm eff}$37 sideband suppression at peak conversion efficiency $\mathbf k_{\rm eff}$38 ($\mathbf k_{\rm eff}$39), and proof-of-principle gravimetry yielding $\mathbf k_{\rm eff}$40 (Kodigala et al., 2022). This is significant as an enabling technology rather than a new interferometer geometry: the complexity of LPAI often resides in the laser system, and photonic integration directly targets miniaturization and ruggedization (Kodigala et al., 2022).

Species-specific and unconventional platforms broaden the scope further. A Bragg-based antimatter interferometer proposal aims at antihydrogen gravimetry with magnetic confinement and atom recycling, projecting initial accuracy better than $\mathbf k_{\rm eff}$41 for the free-fall acceleration and improvement to the part-per-million level (Hamilton et al., 2013). A BEC-based multipath interferometer has been proposed for a Born-rule test with realistic statistical uncertainty $\mathbf k_{\rm eff}$42 and $\mathbf k_{\rm eff}$43 (Kanthak et al., 2024). A single-light-pulse, weak-measurement-based compact interferometer proposal claims an effective momentum-offset amplification of order $\mathbf k_{\rm eff}$44 in simulation using cesium atoms, although this is a proposal published after the present date and should therefore be treated as future literature rather than established experimental practice (Jiang et al., 30 Oct 2025).

6. Quantum-optical, relativistic, and systematic effects

At current precision levels, LPAI must account for effects that are negligible in elementary treatments. One class of effects concerns the quantization of the light fields themselves. In models where the pulses are quantized traveling-wave modes, the beam-splitter and mirror operators become operator-valued in photon number, and low photon number can encode which-way information into the light, reducing fringe visibility (Soukup et al., 2021). Soukup et al. show that while the diffraction pattern for a Fock-state pulse can match the classical result, the full Mach–Zehnder interference differs sharply: if one pulse is in a pure Fock state, the cross term vanishes and the visibility is zero; coherent states recover the classical limit only as the mean photon number becomes large (Soukup et al., 2021). Asano et al. extend this by demonstrating that entanglement among the three light pulses can partially erase which-path information, with $\mathbf k_{\rm eff}$45 for a GHZ-like Fock-state choice and $\mathbf k_{\rm eff}$46 when suitable single-mode superpositions are added (Asano et al., 2022).

A second class concerns relativistic and propagation effects. In single-photon clock-transition interferometers, the total phase difference between arms can be expressed as the internal-state action difference plus pulse phases, and in the comoving Fermi–Walker frame one obtains

$\mathbf k_{\rm eff}$47

so the device directly measures proper-time differences accumulated by freely falling atoms (Roura, 2024). The proposal is aimed at MAGIS-100 and 10 m prototypes and uses forward/reverse beam directions together with gradiometric differencing to suppress Doppler, gradient, and rotation terms (Roura, 2024).

Finite-speed-of-light (FSL) effects become important as arm separation grows. A 2025 analysis develops a theory in which the eikonal phase of chirped light in a Rindler metric and the atomic Hamiltonian including mass defect yield explicit $\mathbf k_{\rm eff}$48 phase perturbations (Niehof et al., 5 May 2025). For a standard Mach–Zehnder, the unperturbed phase is $\mathbf k_{\rm eff}$49, and the leading FSL, Doppler, chirp-induced, and atomic time-dilation terms can be separated (Niehof et al., 5 May 2025). A central result is that for resonant two-photon Bragg or Raman diffraction, the terms proportional to the mean velocity at the mirror pulse cancel, so the phase is free of dependence on that velocity to $\mathbf k_{\rm eff}$50; in contrast, single-photon transitions retain a large clock-type shift even on resonance (Niehof et al., 5 May 2025). The paper further proposes a recoilless E1–M1 experiment to test this prediction and mitigation strategies such as chirp tuning, timing offsets, and resonant Bragg operation (Niehof et al., 5 May 2025).

Dilaton and modified-gravity analyses add another layer. In a weak Newtonian metric plus light scalar field, the electromagnetic phase obeys the usual eikonal equation, so no additional dilaton-dependent phase enters through light propagation at leading order, even though the light amplitude is modulated (Pumpo et al., 2022). Gravity, however, does modify the effective momentum transfer and finite-speed-of-light delay, contributing corrections that must be included once sensitivities reach the $\mathbf k_{\rm eff}$51–$\mathbf k_{\rm eff}$52 regime (Pumpo et al., 2022).

Systematic effects tied to finite beam size and cloud geometry are equally important. Morel et al. showed experimentally that Gaussian-beam intensity variation across moving atoms causes an imperfect cancellation of light-pulse displacement phases, yielding the velocity-dependent phase shift already noted (Morel et al., 2020). Zheng et al. argued that the finite transverse size of the atom wave function itself shifts the effective wave vector of the absorbed photon and thereby the interferometric phase (Sun et al., 2018). These results address a recurrent misconception that $\mathbf k_{\rm eff}$53 is purely a laser-defined parameter independent of the atomic spatial state. In precision LPAI, beam geometry, optical mode structure, and atomic transverse distribution jointly determine the actual momentum transfer (Sun et al., 2018, Morel et al., 2020).

7. Applications, performance scaling, and outlook

The principal applications of LPAI are gravimetry, gradiometry, inertial navigation, gyroscopy, measurements of fundamental constants, tests of the equivalence principle, relativistic time-dilation measurements, and proposed searches for dark matter and gravitational waves (Kleinert et al., 2015, Roura, 2024, Pumpo et al., 2022). The generic sensitivity scaling $\mathbf k_{\rm eff}$54 motivates three broad development paths: larger momentum transfer, longer interrogation time, and better atom-optical fidelity (Béguin et al., 2023).

Large-momentum transfer directly boosts $\mathbf k_{\rm eff}$55, as emphasized by coherent enhancement of Bragg pulse sequences (Béguin et al., 2023). Long-baseline devices exploit large $\mathbf k_{\rm eff}$56, as in the 10 m point-source interferometer with $\mathbf k_{\rm eff}$57 (Dickerson et al., 2013). Optical cavities enable compact geometries with low optical power, stable wavefronts, and potential self-aligned multi-axis configurations via transverse modes (Hamilton et al., 2014). Multidimensional interferometers seek vector readout of all acceleration and rotation components in a single shot (Barrett et al., 2019). Single-photon clock-transition devices aim to couple interferometric readout to proper-time differences and mid-band gravitational-wave or ultralight dark-matter searches (Roura, 2024).

Several works also target readout and platform engineering. Silicon photonic modulation addresses the complexity of the laser system and points to portable, integrated cold-atom sensors (Kodigala et al., 2022). Polarimetric detection proposes non-destructive or single-shot alternatives to fluorescence counting, although the cited work is a proposal and its performance claims remain prospective (Muradyan, 20 Jun 2025). Frequency-comb operation extends LPAI to spectral regions not easily reached by continuous-wave laser systems and may enable work with species requiring UV, VUV, or XUV transitions (Solaro et al., 2022).

There are, however, clear limits and controversies in the broader research landscape. First, many performance projections rely on idealized assumptions about pulse fidelity, beam quality, or environmental control. For example, the path from demonstrated $\mathbf k_{\rm eff}$58 Bragg splitting to $\mathbf k_{\rm eff}$59–$\mathbf k_{\rm eff}$60 rests on numerical simulations in specific CEBS regimes rather than present experimental demonstration (Béguin et al., 2023). Second, certain architectures address narrow regimes: cavity interferometers offer superb mode control but impose constraints from cavity length noise, mirror vibrations, sideband balance, and mode volume (Hamilton et al., 2014); point-source interferometers gain long $\mathbf k_{\rm eff}$61 but demand large facilities (Dickerson et al., 2013); single-photon clock-transition designs promise direct time-dilation sensitivity but require stringent control of chirp, gradients, Zeeman shifts, and black-body gradients (Roura, 2024).

A plausible implication is that LPAI will continue to diversify rather than converge to a single canonical architecture. High-sensitivity terrestrial gravimeters, compact cavity-based inertial sensors, long-baseline relativistic detectors, and quantum-optical testbeds with quantized or entangled light address different operating points in the design space. What unifies them is the same underlying principle: laser pulses define coherent atom-optical elements whose momentum transfer, phase imprint, and space-time placement generate an interferometric observable. The continued refinement of those elements—through better theory, higher-fidelity diffraction, integrated photonics, and tailored geometries—defines the modern trajectory of light-pulsed atom interferometry (Kleinert et al., 2015, Béguin et al., 2023, Hamilton et al., 2014).