arXiv subjects

Yiyu Zhou

Publications and source records attributed to Yiyu Zhou.

At least 19 recordsLinked to original sources

arXiv2026

Energy-Energy Correlators in $Z$-Tagged Jets in $pp$ Collisions

We present predictions for the collinear energy-energy correlator (EEC) measured inside $Z$-tagged jets in proton-proton collisions across the confinement transition. Our framework combines transverse-momentum-dependent factorization for back-to-back $Z+$jet production with an exclusive differential EEC jet function incorporating perturbative evolution and flavor-dependent non-perturbative fragmentation. The EEC jet function is evaluated at $\mathrm{NLL}^{\prime}$ accuracy, with separate quark and gluon non-perturbative scales constrained by existing $e^+e^-$ and inclusive-jet data. We provide predictions for forward $Z+$jet production at $\sqrt{s}=8~\mathrm{TeV}$ and $13~\mathrm{TeV}$ in the jet transverse-momentum intervals $(20, 30)$, $(30, 50)$ and $(50, 100) \, \mathrm{GeV}$. The EEC distributions as functions of $z_χ$ exhibit finite plateaus at small $z_χ$, while the corresponding angular distributions display the characteristic turnover associated with the confinement transition. A flavor decomposition shows that this transition becomes increasingly dominated by quark-initiated jets as the jet transverse momentum increases. Forward $Z$-tagged jets therefore provide a clean probe of non-perturbative quark fragmentation and offer a direct test of whether the characteristic confinement scale extracted from $e^+e^-$ collisions remains universal in a hadronic environment.

hep-ph↗

arXiv2026

Polarized jet anisotropy at the Electron-Ion Collider

Jets provide a powerful probe of the three-dimensional spin structure of the nucleon, a central goal of the Electron-Ion Collider. Yet the observed jet defines an axis that breaks the azimuthal isotropy of soft-gluon radiation, thereby reshaping the very asymmetries used to extract that structure. Using transverse-momentum-dependent (TMD) QCD factorization, we show for the first time that this jet-induced anisotropy imposes a parity selection rule on polarized asymmetries. Expanding the transversely polarized structure functions in harmonics $\cos(nϕ_{qJ})$, where $ϕ_{qJ}$ is the angle between the jet and the lepton-jet momentum imbalance, makes this rule explicit: the symmetry of each harmonic is fixed by the parity of $n$, independently of the magnitudes of the harmonic coefficients. For the Sivers function, the canonical left-right asymmetry about the proton spin survives for even $n$ but is replaced by a counterintuitive left-right symmetry for odd $n$. The worm-gear function retains its up-down asymmetry at every harmonic while being left-right symmetric for even $n$ and asymmetric for odd $n$. At EIC kinematics, the higher harmonics studied here are predicted to be individually measurable, providing new observables for the azimuthal dynamics of soft radiation and an essential ingredient in precision extractions of nucleon structure.

hep-ph↗

arXiv2026

Transition from classical to ultimate melting

Melting is omnipresent in nature and technology, with applications ranging from metallurgy, biology, food science, and latent thermal energy storage to oceanography, geophysics, and climate science, and occurring on all scales from sub-millimeter to global scales. The key objective is to understand the rate at which an object melts as a function of its size and of the ambient conditions. To achieve this it is important to be able to extrapolate from small scale experiments and observations to large or even global scales. This is done by scaling laws. However, these are only meaningful if there is no transition from one scaling relation to another one. Here we show, however, that for both fixed and freely-advected melting objects immersed in a turbulent flow a melting transition does exist, namely from slow melting at the small scales to fast melting at the large scales. We do so by controlled melting experiments and corresponding direct numerical simulations, covering four orders of magnitude in scale. The transition corresponds to the transition from a laminar-type boundary layer around the melting object to a turbulent-type boundary layer, i.e., from so-called classical turbulence to ultimate turbulence, with its enhanced transport properties. Our results thus provide a quantitative understanding of the flow physics of the melting process and thereby enable a better extrapolation and prediction of melt rates on large scales such as relevant in geophysics, oceanography, and climate science.

physics.flu-dyn↗

arXiv2026

Quantum entanglement within quarkonium

We investigate quark-antiquark entanglement in heavy quarkonium within a nonperturbative light-front Hamiltonian framework. By tracing over the antiquark degrees of freedom in the hadronic state vector, we construct the reduced density matrix of the quark subsystem and compute the associated von Neumann entropy. For spin-0 quarkonia, we show that this entropy reduces to the Shannon entropy of the unpolarized transverse momentum dependent parton distribution (TMD), up to constant color and spin contributions. For spin-1 quarkonia, we derive the explicit polarization dependence of the entropy and connect it to polarized and tensor-polarized TMDs. Using light-front wave functions obtained via basis light-front quantization (BLFQ), we evaluate the entanglement entropy for charmonium and bottomonium states, revealing a pronounced sensitivity to the polarization of vector mesons. Furthermore, we resolve the infrared parameter by matching the momentum-space entropy to a harmonic-oscillator representation. Ultimately, these results establish entanglement entropy as a novel probe of nonperturbative quarkonium structure, forging a direct link between quantum information measures and partonic observables.

hep-ph↗

arXiv2026

Accessing gluon polarization with high-$P_T$ hadrons in SIDIS

A recent global QCD analysis of jet production and other polarized scattering data has found the presence of negative solutions for the gluon helicity distribution in the proton, $Δg$, along with the traditional $Δg > 0$ solutions. We consider polarized semi-inclusive deep-inelastic scattering for hadrons produced with large transverse momentum as a means of constraining the dependence of $Δg$ on the parton momentum fraction, $x$. Focusing on the double longitudinal spin asymmetry, we identify the kinematics relevant for future experiments at Jefferson Lab and the Electron-Ion Collider which are particularly sensitive to the polarized gluon channel and could discriminate between the different $Δg$ behaviors.

hep-ph↗

arXiv2026

Exploring nuclear modification using one-point energy correlator at the electron-ion collider

We study the one-point energy correlator (OPEC) at both the back-to-back and collinear limits in electron-proton and electron-nucleus collisions. We provide the factorization formalism for the two types of OPEC and present phenomenological predictions in the kinematic region relevant for the future Electron-Ion Collider. Focusing on cold nuclear matter effects in electron-nucleus scattering, we demonstrate that the OPEC serves as a powerful probe of the transverse momentum dependent (TMD) physics and in characterizing the medium-induced transverse momentum broadening in cold nuclear matter.

hep-ph↗

arXiv2026

Quantum entanglement between partons in a strongly coupled quantum field theory

We perform a first-principles, non-perturbative investigation of quantum entanglement between partonic constituents in a strongly coupled 3+1-dimensional scalar Yukawa theory, using light-front Hamiltonian methods with controlled Fock-space truncations. By explicitly constructing reduced density matrices for (mock) nucleon, pion, and anti-nucleon subsystems from light-front wave functions, we compute key entanglement witnesses, including von Neumann entropy, mutual information, and linear entropy, in both quenched (no sea pairs) and unquenched frameworks. We find that the entanglement entropy is closely related to the Shannon entropy of the transverse momentum dependent distribution, establishing a link between quantum information and parton structure. In contrast, the unquenched theory reveals genuinely non-classical correlations: the entanglement entropy cannot be reduced to any Shannon entropy of normalized parton distributions, demonstrating that the full hadronic wave function encodes quantum information beyond classical probabilities. Our findings highlight the role of entanglement as a fundamental probe of non-perturbative dynamics in relativistic quantum field theory and lay the groundwork for extending these concepts to QCD and future collider phenomenology.

hep-ph↗

arXiv2026

A frequency-agile microwave-optical interface for superconducting qubits

Superconducting quantum processors operate at microwave frequencies in millikelvin environments, making it challenging to interconnect distant nodes using conventional microwave wiring. Coherent microwave-to-optical (M2O) transduction enables superconducting quantum networks by interfacing itinerant microwave photons with low-loss optical fiber. However, many state-of-the-art transducers provide efficient conversion only over a narrow frequency span, complicating deployment with heterogeneous superconducting devices that are detuned by gigahertz-scale offsets. Here we demonstrate a frequency-agile microwave-optical interface that overcomes this bandwidth mismatch by cascading an electro-optic M2O transducer with a multimode microwave-to-microwave (M2M) frequency converter, with in situ tunability of the microwave resonances in both stages. Using this architecture, we realize continuous frequency coverage from 5.0 to 8.5 GHz within a single system. As an application relevant to superconducting-qubit networking, we use the cascaded M2M-M2O interface to optically read out a superconducting qubit whose readout resonator is detuned by 1.7 GHz from the native M2O microwave resonance, demonstrating a scalable route toward fiber-linked superconducting quantum nodes.

quant-ph↗

arXiv2025

An epsilon-near-zero-based nonlinear platform for ultrafast re-writable holography

We re-examine real-time holography for all-optical structuring of light and optical computation using a contemporary material: a subwavelength-thick, spatially unstructured film of indium tin oxide (ITO). When excited by spatially structured light at epsilon-near-zero frequencies, the film acts as an efficient and reconfigurable diffractive optical platform for all-optical modulation of light such as spatial structuring and optical computations. We demonstrate a few percent of absolute diffraction efficiency over greater than 300 nm bandwidth around telecom wavelengths using a film four orders of magnitude thinner than and up to six orders of magnitude faster than standard holographic materials. Our findings highlight the potential of using epsilon-near-zero-based nanostructures for efficient modulation of spatially structured light and rapid prototyping without complex nanofabrication processes.

physics.optics↗

arXiv2025

Global analysis of fragmentation functions to light neutral hadrons

Fragmentation functions (FFs) are crucial non-perturbative components in quantum chromodynamics (QCD), playing a vital role in predictions and understanding of the hadronization process. In this paper, we present the FFs for $K_S^0$, $η$, $π^0$ mesons, and $Λ$ baryons in the context of global QCD analysis. The data included in the fit are from single inclusive $e^+ e^-$ annihilation (SIA), semi-inclusive deep-inelastic scattering (SIDIS) and proton-proton collisions, with kinematic cuts carefully applied to ensure validity of collinear factorization and perturbative QCD expansion. For the first time, data from SIDIS and hadron-in-jet production in SIA have been incorporated into the extraction of FFs for light-flavor neutral hadrons. Our analysis reveals that these data play a critical role in constraining the gluon distribution, and in distinguishing between different quark flavors. Pulls from different datasets are also studied by performing alternative fits with systematically subtracting groups of data from the nominal fit. For the quality of the fit, good $χ^2$ values are achieved for most of the datasets, and FFs are generally well constrained within the momentum fraction region $\pqty{0.1, 0.5}$. The extracted $K_S^0$ fragmentation functions, together with the $K_S^0$ FFs constructed from $K^{\pm}$ FFs via isospin symmetry, are used to test isospin symmetry in kaon fragmentation. Although a definitive conclusion cannot be reached yet, these studies have identified several potential measurements that can be performed at existing facilities, which may ultimately help us to arrive at a conclusive answer. With the comprehensive species of FFs extracted within the NPC framework, we are able to perform a test on the momentum sum rule with the light-flavor charged and neutral hadrons.

hep-ph↗

arXiv2025

A kilometer photonic link connecting superconducting circuits in two dilution refrigerators

Superconducting quantum processors are a leading platform for implementing practical quantum computation algorithms. Although superconducting quantum processors with hundreds of qubits have been demonstrated, their further scaling up is constrained by the physical size and cooling power of dilution refrigerators. This constraint can be overcome by constructing a quantum network to interconnect qubits hosted in different refrigerators, which requires microwave-to-optical transducers to enable low-loss signal transmission over long distances. Despite that various designs and demonstrations have achieved high-efficiency and low-added-noise transducers, a coherent photonic link between separate refrigerators has not yet been realized. In this work, we experimentally demonstrate coherent signal transfer between two superconducting circuits housed in separate dilution refrigerators, enabled by a pair of frequency-matched aluminum nitride electro-optic transducers connected via a 1-km telecom optical fiber. With transducers at each node achieving >0.1% efficiency, an overall 80 dB improvement in transduction efficiency over commercial electro-optic modulators is attainable, paving the way towards a fully quantum-enabled link. This work provides critical design guidelines towards scalable superconducting quantum networks interconnected by photonic links.

quant-ph↗

arXiv2025

Transverse Energy-Energy Correlator for Vector Boson-Tagged Hadron Production in $pp$ and $pA$ collisions

We investigate the transverse energy-energy correlator (TEEC) event-shape observable for back-to-back $γ+ h$ and $Z + h$ production in both $pp$ and $pA$ collisions. Our study incorporates nuclear modifications into the transverse-momentum dependent (TMD) factorization framework, with resummation up to next-to-leading logarithmic (NLL) accuracy, for TEEC as a function of the variable $τ= \left(1 + \cosϕ \right)/2$, where $ϕ$ is the azimuthal angle between the vector boson and the final hadron. We analyze the nuclear modification factor $R_{pA}$ in $p\mathrm{Au}$ collisions at RHIC and $p\mathrm{Pb}$ collisions at the LHC. Our results demonstrate that the TEEC observable is a sensitive probe for nuclear modifications in TMD physics. Specifically, the changes in the $τ$-distribution shape provide insights into transverse momentum broadening effects in large nuclei, while measurements at different rapidities allow us to explore nuclear modifications in the collinear component of the TMD parton distribution functions in nuclei.

hep-ph↗

arXiv2025

Relativistic dynamics of charmonia in strong magnetic fields

We investigate the properties of charmonium systems in strong external magnetic fields using a relativistic light-front Hamiltonian approach within the Basis Light-Front Quantization (BLFQ) framework. By solving the eigenvalue problem for the invariant mass squared operator with confinement potentials and one-gluon-exchange interactions, we obtain the mass spectrum and wave functions under varying magnetic fields. Our results reveal significant spectral modifications via the Zeeman effect, including $η_c$-$J/ψ$ mixing and magnetic sublevel splitting. Momentum density analysis demonstrates wave function deformation, with transverse momentum broadening and longitudinal narrowing under strong fields, alongside structural shifts in parton distributions such as double-hump profiles in excited states. Relativistic corrections and center-of-mass coupling critically drive these dynamics, highlighting the necessity of a relativistic framework for QCD bound states in extreme magnetic environments.

hep-ph↗

arXiv2025

Degeneracy-Locked Optical Parametric Oscillator

Optical parametric oscillators (OPOs) are widely utilized in photonics as classical and quantum light sources. Conventional OPOs produce co-propagating signal and idler waves that can be either degenerately or non-degenerately phase-matched. This configuration, however, makes it challenging to separate signal and idler waves and also renders their frequencies highly sensitive to external disturbances. Here, we demonstrate a degeneracy-locked OPO achieved through backward phase matching in a submicron periodically-poled thin-film lithium niobate microresonator. While the backward phase matching establishes frequency degeneracy of the signal and idler, the backscattering in the waveguide further ensures phase-locking between them. Their interplay permits the locking of the OPO's degeneracy over a broad parameter space, resulting in deterministic degenerate OPO initiation and robust operation against both pump detuning and temperature fluctuations. This work thus provides a new approach for synchronized operations in nonlinear photonics and extends the functionality of optical parametric oscillators. With its potential for large-scale integration, it provides a chip-based platform for advanced applications, such as squeezed light generation, coherent optical computing, and investigations of complex nonlinear phenomena.

physics.optics↗

arXiv2025

Broad Spectrum Coherent Frequency Conversion with Kinetic Inductance Superconducting Metastructures

Parametric frequency converters (PFCs) play a critical role in bridging the frequency gap between quantum information carriers. PFCs in the microwave band are particularly important for superconducting quantum processors, but their operating bandwidth is often strongly limited. Here, we present a multimode kinetic metastructure for parametric frequency conversion between broadly spanning frequency modes. This device comprises a chain of asymmetric kinetic inductance grids designed to deliver efficient three-wave mixing nonlinearity. We demonstrate high efficient coherent conversion among broadly distributed modes, and the mode frequency is continuously tunable by controlling the external magnetic field strength, making it ideally suited for quantum computing and communication applications requiring flexible and efficient frequency conversion.

quant-ph↗

arXiv2024

High-efficiency, cryogenic-compatible grating couplers on an AlN-on-sapphire platform through bottom-side coupling

Sapphire is a commonly used substrate for wide-bandgap III-nitride photonic materials. However, its relatively high refractive index results in low transmission efficiency in grating couplers. Here, we propose and demonstrate that the transmission efficiency can be significantly enhanced by bottom-side coupling. A metal reflector is deposited on the top side of the chip, and the fiber array is glued to the bottom side of the substrate. We experimentally achieve a transmission efficiency as high as 42% per coupler on an aluminum nitride (AlN) on sapphire platform at the telecom wavelength. In addition, the grating couplers show a robust performance at a cryogenic temperature as low as 3~K for both transverse-electric (TE) and transverse-magnetic (TM) modes. Our results can be useful to a wide range of sapphire-based applications that require low coupling loss and cryogenic operation.

physics.optics↗

arXiv2024

Integrated photonic Galton board and its application for photon counting

The Galton board is a desktop probability machine traditionally used to visualize the principles of statistical physics with classical particles. Here, we demonstrate a photonic Galton board that enables on-chip observation of single-photon interference. The photonic Galton board, which can be considered as a simplified Boson sampler, consists of a directional coupler matrix terminated by an array of superconducting nanowire detectors to provide spatiotemporal resolution. This design also allows for photon-number-resolving capability, making it suitable for high-speed photon counting. Our results demonstrate the compatibility between single-photon detector array and photonic integrated circuits, paving the way for implementing on-chip large-scale quantum optics experiments and photonic quantum computing.

quant-ph↗

arXiv2024

Heterogeneous sapphire-supported low-loss photonics platform

Sapphire is a promising wideband substrate material for visible photonics. It is a common growth substrate for III-nitride light-emitting diodes and laser structures. Doped sapphires are important gain media foundational to the development of titanium-sapphire and ruby lasers. For lasers operating at visible and near-infrared wavelengths, a photonic platform that minimizes loss while maximizing gain material overlap is crucial. Here, we introduce a novel low-loss waveguiding strategy that establishes high-performance integrated photonics on sapphire substrates. This platform achieves a high intrinsic quality factor of 5.6 million near 780 nm and features direct compatibility with a range of solid-state laser gain media.

physics.optics↗