Optics
Calibration-Free Photonic Memory in a Silicon Photonics Platform
Ankur Singh and Akhilesh Jaiswal
We propose a calibration-free photonic
memory bitcell based on nonresonant variable optical attenuators in the GlobalFoundries 45SPCLO platform. The
cell maintains complementary electrical states through electro-optical feedback without cavity-resonance
alignment. Wordline-controlled attenuators enable selective writing through differential optical bitlines, while optical readout shares the holding input and output splitters, avoiding additional read attenuators or a separate
laser source.
Circuit simulations demonstrate writing with $10~\mathrm{ps}$ optical pulses at $2~\mathrm{mW}$ peak power. The
cell retains data as long as optical and electrical power are supplied, with retention simulated for $5~\mathrm{s}$ per logic state. The evaluated transition consumes an incremental write energy of $0.562~\mathrm{pJ}$, including
circuit electrical energy and the
laser contribution at 20% wall-plug efficiency. The bitcell layout occupies $147.92\times219.93~\mu\mathrm{m}^{2}$.
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Optics
Three-Wave Mixing as a High-Throughput Diagnostic Tool for Nonlinear Waveguides
Yi-Yang Liu, Kevin Chen, Kyungduk Kim et al. (+4 more)
The recent development of wavelength-scale nonlinear waveguides highlights the need for new diagnostic methods that characterize both waveguide dispersion and fabrication-induced spatial inhomogeneities. While tightly confining waveguides enable compact and highly efficient nonlinear devices, nanometer-scale waveguide nonuniformities can limit the effective interaction length and conversion efficiency. In this work, we establish a high-throughput diagnostic method for second-order nonlinear waveguides based on near-degenerate three-wave mixing, hereafter referred to as sum-frequency
tomography (SFT). In contrast with conventional diagnostics based on second-harmonic generation, SFT produces two-dimensional transfer functions that allow dispersion orders to be characterized separately from longitudinal phase-mismatch variations. We validate this technique using commercially available PPLN waveguides and show that SFT recovers the group-velocity mismatch between the interacting waves, the group-velocity dispersion of the fundamental, and a low-order
polynomial approximation of the longitudinal phase-mismatch profile. SFT avoids the experimental complexities of phase-sensitive or spatially resolved measurements, enabling the characterization of individual waveguides in seconds.
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All authors Yi-Yang Liu, Kevin Chen, Kyungduk Kim, Ryotatsu Yanagimoto, Edwin Ng, Timothy P. McKenna, Marc Jankowski
Optics
High-power photoconductive THz emitters for fast parallel electro-optic detection
Mohsen Khalili, Robin Löscher, Anna Martinez et al. (+3 more)
The terahertz (THz) region is highly attractive for imaging because it penetrates many optically opaque materials and can distinguish them by composition. Among the various methods that allow us to access this spectral region, THz time-domain spectroscopy (THz-TDS) is uniquely suited to retrieve broadband information, recording the full waveform of the THz electric field to recover both amplitude and phase with high sensitivity. Translating this capability into fast, wide-field imaging has however remained a major challenge, largely because the low average power of conventional TDS sources forces a trade-off between acquisition speed, field of view, and sensitivity. Here we demonstrate a hyperspectral THz camera in which a high-average-power, pulsed broadband THz source, delivering 38.3 mW at a 400 kHz repetition rate, drives parallel electro-optic detection over a wide field of view at high acquisition rates. The system simultaneously records the full THz waveform, in amplitude and phase, across 145,000 pixels over a ~14.5 mm field of view at an acquisition rate of 2 Hz. These results demonstrate the potential of high-average-power THz-TDS for broadband, high-speed imaging, opening applications such as inline material-resolved inspection and the spectroscopic imaging of irreversible, second-timescale processes such as hydration in biologically relevant systems.
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All authors Mohsen Khalili, Robin Löscher, Anna Martinez, Abhishek Singh, Stephan Winnerl, Clara J. Saraceno
Optics · Cross-listed from quant-ph
Negative quasiprobabilities redistribute (and complex ones reduce) the information in unabsorbed photons
Jonte R. Hance
Negative Kirkwood–Dirac quasiprobabilities are credited with the
quantum advantage of interaction-free measurement and postselected metrology. We test that claim on the task interaction-free measurement was designed for: learning about a sample letting it absorb as little light as possible. The Kirkwood–Dirac distribution of path and output gives the linear response to a weak sample: its real part responds to absorption, its imaginary part to a phase. For a pure single
photon passing once through any interferometer, the Fisher information about transmittance per absorbed
photon is the direct-transmission value minus a sum of squared imaginary parts: no interferometer or readout beats direct transmission. Negativity plays no role beyond concentrating information in weakly lit outputs. The imaginary parts of the Kirkwood-Dirac distribution depend on the output basis here, not on the sample, so a basis exists in which every term is real, which is optimal. A single
photon gains information per absorbed
photon only through a phase response, which for an optical line needs a thick or inhomogeneously broadened sample, or through many passes when absorptions go uncounted, as shown by a critically coupled resonator. For detecting a weak absorber, negativity gives a single-shot advantage that does not accumulate over multiple trials; advantage instead accumulates when there are outputs which are dark without the object, a case which needs no negativity.
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Optics · Cross-listed from cond-mat.quant-gas
Krylov complexity of a tilted extended Bose-Hubbard chain with Rydberg-dressed interactions
Yifan Chen, Tianyi Yan, Lu Qin et al. (+1 more)
We investigate Krylov state complexity in a tilted extended Bose-Hubbard chain in which both the on-site interaction $U$ and nearest-neighbor interaction $V$ are present. The tilted extended Bose-Hubbard model can be realized with Rydberg-dressed interactions in optical
lattices. Using exact diagonalization and Lanczos recursion from three physically motivated Fock states, we compute the time-dependent complexity, its long-time saturation value, and the fluctuations of the Lanczos coefficients for an open chain at unit filling. Crucially, we identify a pronounced quasi-chaotic diagonal regime near $U\simeq V$ in which the Krylov complexity saturation exhibits a sharp ridge while the spectral level-spacing statistics remain partially chaotic. This dissociation arises from the competition between the on-site and nearest-neighbor interaction, which generates a dense
manifold of near-resonant many-body configurations that is efficiently coupled by the state-dependent dynamics but retains residual spectral structure. Our results show that Krylov state complexity provides complementary, state-sensitive information about many-body chaos that is not captured by the spectral diagnostics alone, establishing Krylov complexity as a useful diagnostic for studying thermalization and information scrambling in experimentally accessible
quantum simulators.
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All authors Yifan Chen, Tianyi Yan, Lu Qin, Weibin Li
Optics · Cross-listed from physics.chem-ph
Electronic Symmetry and Femtosecond Coherence Dynamics of Renner-Teller-Mixed Neutral Vibronic States in Carbon Dioxide
Eric Liu, Shashank Kumar, Siddhant Pandey et al. (+7 more)
When non-adiabatic coupling mixes electronic states of a molecule, vibronic states of different electronic
symmetry become interleaved across the same spectral region. The
symmetry of these states cannot be accessed in conventional spectroscopy due to orientation averaging. We show that molecular-frame angular signatures, which are preserved even when states with different
symmetry overlap in energy, can be used to resolve them. Using
vacuum-ultraviolet transient absorption spectroscopy of aligned carbon dioxide molecules, we separate two electronically distinct classes of vibronic states ($A^{'}$ and $A^{''}$) that arise from Renner-Teller splitting of the $^1\Delta_u$ state. We reconstruct molecular-frame anisotropy continuously across the vibronic
manifold showing that the anisotropy crosses over from perpendicular to parallel transition character and maps the interleaved electronic
symmetry landscape. By scanning the femtosecond delay between the VUV and a near-infrared pulse through temporal overlap, we measure
symmetry-dependent coherence dephasing times of these states and find that the parallel ($A^{'}$) states dephase faster than the perpendicular ($A^{''}$) states. We attribute this to faster departure of the $A^{'}$ wavepacket from the Franck-Condon region due to the distinct
topology of the $A^{'}$ excited-state surface. These measurements probe
symmetry-resolved ultrafast wavepacket dynamics on the coupled excited-state potential energy surfaces.
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All authors Eric Liu, Shashank Kumar, Siddhant Pandey, Tzu-Hsien Tan, Russell Zimmerman, Kousik Bera, Anthony Fiore, Paul Hockett, Varun Makhija, Niranjan Shivaram
Optics
Design of Mechanically Compliant Membrane Reflectors for Giant Optical Phase Nonlinearity
Lior Michaeli and Harry A. Atwater
Optical nonlinearities arise when the response of a photonic system depends on light intensity. Radiation pressure can create such a nonlinearity by moving a mechanically compliant reflector, thereby shifting the phase of the reflected light. Based on measured properties, we predict a giant phase responsivity of 263 rad W$^{-1}$ and a device-equivalent $n_{2,\mathrm{eff}} = 5.4 \times 10^{-7}$ m$^2$ W$^{-1}$ for a silicon nitride membrane trampoline with serpentine springs. We introduce strength-range-aperture metrics for reflective phase elements. Among reported mechanical resonators compared under a common direct-reflection protocol, this trampoline is an outlier, combining high compliance, practical optical accessibility, and 99.85% retention of its small-signal phase responsivity through a full $2\pi$ reflected-phase shift. Practical implementation requires optical and thermal co-design. Our framework indicates design priorities for future mechano-optical phase elements.
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Optics · Cross-listed from cond-mat.quant-gas
Room-temperature polariton supersolids
Yuanhao Gong, Jingwen Ma, Shuang Zhang et al. (+2 more)
Exploring exotic
quantum phases of matter at room temperature represents a frontier challenge in modern physics. The supersolid phase, uniquely merging crystalline order with frictionless superfluid flow, stands among the most intriguing macroscopic
quantum phenomena. However, all previous demonstrations of supersolidity, whether in ultracold atomic gases or III-V
semiconductor-based polariton systems, have been strictly confined to cryogenic temperatures. Here, we report the observation of room-temperature supersolids in photonic-
crystal polariton condensates. By integrating a room-temperature-stable perovskite
semiconductor with a dispersion-engineered photonic-
crystal waveguide, we create a polariton condensate with multi-mode dispersion landscapes and pronounced parametric nonlinearities. Above a critical condensation density, the interacting condensates spontaneously break continuous translational
symmetry, creating a non-rigid supersolid phase that simultaneously exhibits emergent crystalline order and global
quantum coherence. This work establishes a room-temperature platform for investigating
quantum hydrodynamics and developing coherent
quantum simulation devices.
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All authors Yuanhao Gong, Jingwen Ma, Shuang Zhang, Xiaobo Yin, Xiang Zhang
Optics
Confocal imaging from biphoton correlations
Euan Millar, Emma Pearce, Daniele Faccio et al. (+1 more)
Confocal microscopy provides optical sectioning for three-dimensional imaging but conventionally relies on point-by-point scanning and physical pinholes, limiting imaging speed. Here, we demonstrate that confocal sectioning can instead arise directly from
quantum measurement, using spatial correlations in entangled biphoton states. Spatially resolved coincidence measurements in a widefield imaging system suppress contributions from out-of-focus planes, producing optical sectioning in parallel across the whole field of view without physical pinholes or mechanical scanning. In addition, this
quantum approach obtains an axial response that, as a result of position-momentum
entanglement, is $\sqrt{2}$-times narrower than that of classical confocal imaging. Our work establishes biphoton correlations as a mechanism for improved confocal imaging and enables parallel, pinhole-free optical sectioning without mechanical scanning.
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All authors Euan Millar, Emma Pearce, Daniele Faccio, Miles J. Padgett
Optics
Near-field Ultrafast Nondiffractive Laser Nanoscale Cutting of Glass with Quasi-null Interface Roughness
Rajeev Dwivedi, Anton Rudenko, Guodong Zhang et al. (+5 more)
Generally, ultrafast
laser glass dicing is governed by explosive material removal, which restricts the achievable surface roughness. Here we report single-step dicing of aluminosilicate glass with residual interface roughness below 5 nm, producing optical-quality surfaces without post-processing, using near-field-enhanced 0th-order Bessel-Gauss beams. This exceptional interface quality cannot be explained by a conventional
laser ablation mechanism, such as phase explosion, melt expulsion, or fracture-dominated material removal. Instead, quantitative analysis of local thermal dynamics indicates that material removal is consistent with a Hertz-Knudsen-type evaporation process, enabling layer-by-layer removal with precision approaching a few molecular layers. These results suggest that nanoscale optical confinement fundamentally alters the response of transparent materials to ultrafast
laser irradiation and establish a route toward deterministic
laser processing with near-atomic precision.
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All authors Rajeev Dwivedi, Anton Rudenko, Guodong Zhang, Xxx Sedao, Yaya Lefkir, Ciro D'Amico, Guanghua Cheng, Razvan Stoian
Optics
Non-additive surface and volume backscattering from a rough interface over a correlated random medium
Mariano Franco and Esteban Calzetta
We compute the first-order incoherent backscattering cross-section of a rough surface over a half-space with randomly fluctuating permittivity, when the two random fields are correlated, so that surface and volume scattering are not additive. A non-orthogonal coordinate transformation flattens the rough boundary and turns the
geometric roughness into volume sources of the same Helmholtz equation as the dielectric fluctuations, propagated by the same Green's function: both mechanisms and their interference follow from one calculation, with no equivalent surface currents and no prescription for the field discontinuity. The
geometric part of the amplitude reproduces the small-perturbation kernel exactly, for any incidence angle, permittivity and profile function. The interference term is obtained for both co-polarized channels, with an explicit surface-dielectric correlation coefficient. The departure from additivity reaches twenty percent at full correlation, changes sign with that coefficient, and is governed by a balance condition and a coherence condition on the depth of the correlated layer. It carries no angular signature and shifts the co-polarized ratio by less than a tenth of a decibel, so an additive inversion absorbs it, biasing the retrieved amplitude of the dielectric fluctuations by tens of percent.
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Optics · Cross-listed from quant-ph
Optical measurement is almost quantum: Quantum inspired universal optical bounds
Daniel Ish and Chase T. Ellis
Inspired by results in
quantum information, we report the development of a formalism for optical sensing which abstracts the details of specific optical systems and allows us to form general bounds on measurement based only on the quantity to be measured. We find a universal bound that controls the performance of any passive optical system regardless of the technology used to construct it and that this bound is attained by a unique measurement scheme for each quantity of interest. Shockingly, our optical formalism is nearly identical to the
quantum formalism, with essentially the same notions of the state to be measured and the operation of the measurement, along with an accompanying uncertainty principle.
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Optics · Cross-listed from cond-mat.mtrl-sci
Phonon-mediated closing of topological Floquet gaps in graphene: Non-phenomenological analysis
Royi Ledermann, Rave Hanoch Saadon, Adam Herling et al. (+1 more)
Floquet band engineering has been intensively studied for its potential to control material properties via
laser driving. In particular, Floquet topological states have been measured on the surface of Bi$_2$Se$_3$. Nonetheless, the original prediction of Floquet topological bands in
graphene remains unobserved, with works only measuring non-topological Floquet-Bloch states or indirect features. Here, we theoretically explore
graphene irradiated by circular
lasers with non-phenomenological electron-
phonon (e-ph) coupling. We show that e-ph interactions substantially broaden Floquet bands due to
graphene's large zero-point motion, as expected from phenomenological treatments. However, we further find that larger displacement $\Gamma$ optical
phonons reduce Floquet gaps by about half, even in absence of instrumentation broadening, and can also induce additional features like flat bands. These
phonons "enter the gap" and blur photoemission signatures. Including non-$\Gamma$
phonons closes the gap and greatly reduces visibility. When these modes couple to reasonably expected instrumentation broadening, the effect is significantly exacerbated. Our results shed light on the missing Floquet topological gaps and also lead to possible mitigation strategies: (i) Pre-pumping coherent
phonons to counteract blurring, or (ii), transition to a Dirac system with more favorable
phonon statistics. Moreover, our real-space analysis proposes that Floquet topological physics is alive in localized regions, such that properties of interest like transport should be accessible. We expect this work to impact experimental analysis and lead to set-ups where
graphene Floquet
topology might finally be directly observed.
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All authors Royi Ledermann, Rave Hanoch Saadon, Adam Herling, Ofer Neufeld
Optics
Topological Fermi-polaron Polaritons with Electrically Invertible Topology
Xin Xie, Chenxi Liu, Yuze Liu et al. (+8 more)
Topological polaritons provide a route to engineer optical Chern bands, but realizing large gaps or efficient electrical tunability remains challenging because time-reversal-
symmetry breaking in
semiconductor polariton systems is typically limited by weak Zeeman splittings. Here, we demonstrate a topological Bose-Fermi mixture — Fermi-polaron polaritons —where large gaps and electrically invertible
topology emerge from the interplay of Fermi-polaron many-body interactions, photonic
symmetry, and strong light–matter coupling. Using a gate-controlled monolayer transition-metal dichalcogenide integrated with a
symmetry-engineered photonic
crystal, we create Fermi-polaron polaritons with topological band structures. The direct coupling between band
topology and gate-tunable many-body interactions provides a mechanism for amplified time-reversal-
symmetry breaking beyond bare Zeeman splitting and enables electrical inversion of topological gaps, Berry
curvature, and Chern numbers. These results establish an electrically reconfigurable platform for interaction-driven topological states and programmable topological photonics.
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All authors Xin Xie, Chenxi Liu, Yuze Liu, Lingxiao Zhou, Chulwon Lee, Yuhan Zhang, Nathanial Lydick, Kenji Watanabe, Takashi Taniguchi, Kai Sun, Hui Deng
Optics
Phase-resolved wide-field CARS microscopy with speckle illumination
Federico Vernuccio, Pascal Berto, Baptiste Marthy et al. (+5 more)
Coherent anti-Stokes Raman scattering (CARS) microscopy enables label-free chemical imaging of biological samples and materials. Conventionally, CARS is implemented using a point-scanning approach that probes a single vibrational mode at a time. Hyperspectral CARS enhances chemical specificity by sequentially addressing multiple Raman modes. However, the measured CARS intensity is distorted by an undesired non-resonant background, which broadens and shifts the Raman peaks, thereby hindering the interpretability of hyperspectral images. Here, we introduce a phase-sensitive, wide-field hyperspectral CARS microscopy scheme that suppresses the non-resonant background. The proposed approach combines three key components: a high-power picosecond tunable optical parametric amplifier (OPA), speckle illumination, and quantitative phase imaging based on quadriwave lateral shearing interferometry (QLSI). The high-power OPA provides the peak power required for efficient nonlinear excitation. Speckle illumination distributes the optical energy over the objective back pupil and mitigates coherent imaging artifacts. QLSI enables the simultaneous measurement of the amplitude and phase of the CARS field, thereby allowing separation of resonant and non-resonant contributions, without the need for an external reference beam. This unique combination enables practical phase-resolved CARS imaging over a field of view exceeding $60 \times 60~\text{\textmu m}^2$ at a frame rate of 1.4 Hz. We illustrate the approach by acquiring hyperspectral images of microplastics and liver steatosis across the entire CH-stretching region.
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All authors Federico Vernuccio, Pascal Berto, Baptiste Marthy, Guillaume Baffou, Sandro Heuke, Randy Bartels, Pierre Bon, Hervé Rigneault
Optics
How Shaped Waves Propagate in Scattering Media
David Gaspard and Arthur Goetschy
The radiative transport equation provides a powerful framework for describing wave propagation in scattering media. However, it cannot describe coherent waves whose incident wavefront is deliberately tailored. Here we establish a transport theory for wavefront-controlled waves based on a
matrix transport equation. Unlike conventional radiative transport, which propagates a scalar radiance, our theory propagates a complex two-by-two
matrix that retains phase information and obeys a nonlinear transport equation, despite the underlying wave dynamics being linear. We use this
matrix transport equation to derive the spatial profiles of the energy and current densities of transmission eigenchannels, from closed to open channels, in arbitrary diffusive systems. Remarkably, these profiles can be expressed analytically in terms of the solution of the conventional radiative transport equation for a random wave in the same medium. The theory further extends to energy loss, including absorption and leakage into uncontrolled channels, revealing
symmetry breaking of transmission eigenchannels in complex structures. Validated against numerical solutions of the wave equation, we establish
matrix transport as a framework for describing and controlling coherent wave propagation in complex media.
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