arXiv subjects

Jia-Qi Wang

Publications and source records attributed to Jia-Qi Wang.

At least 37 records · Page 2Linked to original sources

arXiv2025

Chip-integrated Brillouin Saser Gyroscope

On-chip Brillouin laser gyroscopes harnessing opto-acoustic interaction are an emerging approach to detect rotation, due to their small footprint, excellent stability and low power consumption. However, previous implementations rely solely on optical readout, leaving the simultaneously generated saser (sound amplification by stimulated emission) undetected due to the lack of capability to access the acoustic output. Here, we propose a gyroscope based on saser detection using a suspension-free chip platform that supports low-loss confinement of both optical and acoustic modes. With experimental feasible parameter with optical and acoustic quality factors of 10^5 and 5000, respectively, sasers show significantly suppressed thermal and frequency noises, leading to gyroscope performance that outperforms its optical counterparts. We predict an angle random walk ~0.1 deg/sqrt(h) by saser gyroscope, while a conventional Brillouin laser gyroscope requires significantly higher pump power and optical quality factor to achieve comparable performance. Our work establishes the foundation for active phononic integrated circuits with Brillouin gain, opening avenues in inertial sensing, quantum transduction, and RF signal processing.

physics.optics↗

arXiv2025

Hardware-Efficient Bosonic Module for Entangling Superconducting Quantum Processors via Optical Networks

Scaling superconducting quantum processors beyond single dilution refrigerators requires efficient optical interconnects, yet integrating microwave-to-optical (M2O) transducers poses challenges due to frequency mismatches and qubit decoherence. We propose a modular architecture using SNAIL-based parametric coupling to interface Brillouin M2O transducers with long-lived 3D cavities, while maintaining plug-and-play compatibility. Through numerical simulations incorporating realistic noises, including laser heating, propagation losses, and detection inefficiency, we demonstrate raw entangled bit fidelities of F~0.8 at kHz-level rates over 30 km using the Duan-Lukin-Cirac-Zoller (DLCZ) protocol. Implementing asymmetric entanglement pumping tailored to amplitude damping errors, we achieve purified fidelities F~0.94 at 0.2 kHz rates. Our cavity-based approach outperforms transmon schemes, providing a practical pathway for distributed superconducting quantum computing.

quant-ph↗

arXiv2025

Compact and high-resolution spectrometer via Brillouin integrated circuits

Optical spectrometers are indispensable tools across various fields, from chemical and biological sensing to astronomical observations and quantum technologies. However, the integration of spectrometers onto photonic chips has been hindered by the low spectral resolution or large device footprint with complex multiple channel operations. Here, we introduce a novel chip-integrated spectrometer by leveraging the acoustically-stimulated Brillouin scattering in a hybrid photonic-phononic chip. The Brillouin interaction provides a dynamic reflection grating with a high reflectivity up to 50% and a fast switching time on the microsecond scale, achieving an unprecedented spectral resolution of 0.56 nm over a 110 nm bandwidth using just a single 1 mm-long straight waveguide. This remarkable performance approaches the fundamental limit of resolution for a given device size, validating the potential of the hybrid photonic-phononic device for efficient and dynamically-reconfigurable spectral analysis, and thus opens up new avenues for advanced optical signal processing and sensing applications.

physics.optics↗

arXiv2025

Large-scale programmable phononic integrated circuits

Electronic and photonic chips revolutionized information technology through massive integration of functional elements, yet phonons as fundamental information carriers in solids remain underestimated. Here, we demonstrate large-scale programmable phononic integrated circuits (PnICs) for complex signal processing. We developed a comprehensive library of gigahertz-frequency phononic building blocks that control acoustic wave propagation, polarization, and dispersion. Combining these elements, we demonstrate an ultra-compact 1$\times$128 on-chip acoustic power splitter with unprecedented integration density of 3,000/cm$^2$, a 21-port acoustic frequency demultiplexer with 3.8~MHz resolution, and a four-channel reconfigurable frequency synthesizer. This work establishes scalable phononic integration as the third pillar of information processing alongside electronics and photonics, enabling hybrid chips that combine all three domains for advanced signal processing and quantum information applications.

physics.app-ph↗

arXiv2025

Suspension-Free Integrated Cavity Brillouin Optomechanics on a Chip

Cavity optomechanical systems enable coherent photon-phonon interactions essential for quantum technologies, yet high-performance devices have been limited to suspended structures. Here, we overcome this limitation by demonstrating cavity Brillouin optomechanics in a suspension-free racetrack microring resonator on a lithium-niobate-on-sapphire chip, a platform that merits high stability and scalability. We demonstrate coherent coupling between telecom-band optical modes and a 9.6-GHz phonon mode, achieving a maximum cooperativity of $0.41$ and a phonon quality-factor-frequency product of $10^{13}\,\mathrm{Hz}$. The momentum-matching condition inherent to traveling-wave Brillouin interactions establishes a one-to-one mapping between optical wavelength and phonon frequency, enabling multi-channel parallel operations across nearly $300\,\mathrm{MHz}$ in phonon frequency and $40\,\mathrm{nm}$ in optical wavelength. Our suspension-free architecture provides a coherent photon-phonon interface compatible with wafer-scale integration, opening pathways toward hybrid quantum circuits that unite photonic, phononic, and superconducting components on a single chip.

physics.optics↗

arXiv2025

Proposal for Forward Brillouin Inter-Modal Scattering in Non-suspended Lithium Niobate Waveguides at Visible Wavelengths

Thin-film lithium niobate on sapphire provides an excellent platform for simultaneously confining acoustic and optical modes without suspended structures, enabling efficient acousto-optic modulation through strong piezoelectric coupling. Here, we identify the challenges in realizing the forward Brillouin interaction at visible wavelengths, and overcome the limitation by introducing a quasi-phase-matching scheme through periodic waveguide width modulation. We predict a complete inter-modal optical conversion over 1.1 mm using only 1 mW acoustic power. Our study paves the way for high-performance visible-wavelength acousto-optic devices on integrated platforms.

physics.optics↗

arXiv2025

Fiber-to-chip grating couplers for Lithium Niobate on Sapphire

Lithium Niobate on Sapphire (LNOS) is an emerging platform for photonic integrated circuits, offering unique properties such as a wide transparency window, high nonlinearity, and strong electro-optic, nonlinear, and acousto-optic effects. Efficient light coupling between optical fibers and on-chip waveguides is crucial for practical applications. We present the design, simulation, and experimental demonstration of high-efficiency fiber-to-chip grating couplers for LNOS. The grating coupler design employs a self-imaging approach with a fixed period and linearly diminished filling factor, enabling a negative diffracted angle to match the fiber array and suppress higher-order diffraction. Numerical simulations predict a coupling efficiency of 42% at 1550 nm wavelength. The grating couplers are fabricated on an X-cut, 400 nm thick LN film with a 220 nm etching depth using electron beam lithography and inductively coupled plasma etching. Experimental characterization using a fiber array and a 6-axis displacement stage reveals a single-end coupling efficiency exceeding 20%, confirming the effectiveness of the design. The demonstrated grating couplers pave the way for efficient light coupling in LN-on-Sapphire photonic circuits, enabling diverse applications in classical and quantum information processing, sensing, and nonlinear optics.

physics.optics↗

arXiv2025

Piezomechanical scattering loss in electro-optics quantum transducers

Quantum transduction between microwave and optical photons is essential for building scalable quantum networks, with electro-optics conversion emerging as a promising approach. Recent experiments, however, observe significant quality factor degradation in superconducting microwave cavities when realizing the electro optics transducers. Here, we identify the piezomechanical scattering, where microwave photon loss through phonon radiation into substrate, as a universal dissipation mechanism in these hybrid quantum devices. By establishing a direct analogy to Rayleigh scattering theory, we derive universal scaling laws governing phononic dissipation process. Our analysis reveals a fundamental trade-off that optimizing coherent transduction coupling inevitably increases dissipation, regardless of the configurations of microwave and optical cavities. We propose potential strategies to overcome this challenge. These findings establish piezomechanical scattering as a critical design constraint for quantum transducers and provide insights to optimize their performances toward practical quantum networking.

quant-ph↗

arXiv2025

Proposal of cavity quantum acoustodynamics platform based on Lithium Niobate-on-Sapphire chip

A scalable hybrid cavity quantum acoustodynamics (QAD) platform is proposed. The architecture integrates superconducting transmon qubits with phononic integrated circuits on a single chip made by lithium niobate-on-sapphire substrate. The platform supports tightly confined and guided phononic modes in unsuspended waveguides and microring structures, while the superconducting qubits reside on the sapphire substrate. Efficient piezoelectric coupling between the phononic modes and transmon qubits can be achieved using interdigital transducers as part of the qubit's shunt capacitance. Numerical calculations demonstrate the feasibility of achieving strong coupling between the phononic microring resonator and the transmon qubit. This hybrid cavity QAD platform opens up new opportunities for quantum information processing and the study of novel quantum acoustic phenomena.

quant-ph↗

arXiv2025

Multi-Channel Microwave-to-Optics Conversion Utilizing a Hybrid Photonic-Phononic Waveguide

Efficient and coherent conversion between microwave and optical signals is crucial for a wide range of applications, from quantum information processing to microwave photonics and radar systems. However, existing conversion techniques rely on cavity-enhanced interactions, which limit the bandwidth and calability. Here, we demonstrate the first multi-channel microwave-to-optics conversion by introducing a traveling-wave architecture that leverages a hybrid photonic-phononic waveguide on thin-film lithium niobate (TFLN). Our approach exploits continuous phase-matching rather than discrete resonances, enabling unprecedented operational bandwidths exceeding 40 nm in the optical domain and 250 MHz in the microwave domain. By harnessing the strong piezoelectric and photoelastic effects of TFLN, we achieve coherent conversion between 9 GHz microwave photons and 1550 nm telecom photons via traveling phonons, with an internal efficiency of 2.2% (system efficiency 2.4 *10^-4 ) at room temperature. Remarkably, we demonstrate simultaneous operation of nine conversion channels in a single device. Our converter opens up new opportunities for seamless integration of microwave and photonic technologies, enabling the quantum interface for distributed quantum computing with superconducting quantum processors, high efficient microwave signal processing, and advanced radar applications.

physics.optics↗

arXiv2024

On-chip 7 GHz acousto-optic modulators for visible wavelengths

A chip-integrated acousto-optic phase modulator tailored for visible optical wavelengths has been developed. Utilizing the lithium niobate on sapphire platform, the modulator employs a 7 GHz surface acoustic wave, excited by an interdigital transducer and aligned perpendicular to the waveguide. This design achieves efficient phase modulation of visible light within a compact device length of merely 200 microns, while holds the advantages of easy fabrication and high stability due to simple unsuspended structure. Remarkably, in this high-frequency acoustic regime, the acoustic wavelength becomes comparable to the optical wavelength, resulting in a notable single-sideband modulation behavior. This observation underscores the phase delay effects in the acousto-optics interactions, and opens up new aspects for realizing functional visible photonic devices and its integration with atom- and ion-based quantum platforms.

physics.optics↗

arXiv2024

Variational optimization of the amplitude of neural-network quantum many-body ground states

Neural-network quantum states (NQSs), variationally optimized by combining traditional methods and deep learning techniques, is a new way to find quantum many-body ground states and gradually becomes a competitor of traditional variational methods. However, there are still some difficulties in the optimization of NQSs, such as local minima, slow convergence, and sign structure optimization. Here, we split a quantum many-body variational wave function into a multiplication of a real-valued amplitude neural network and a sign structure, and focus on the optimization of the amplitude network while keeping the sign structure fixed. The amplitude network is a convolutional neural network (CNN) with residual blocks, namely a ResNet. Our method is tested on three typical quantum many-body systems. The obtained ground state energies are lower than or comparable to those from traditional variational Monte Carlo (VMC) methods and density matrix renormalization group (DMRG). Surprisingly, for the frustrated Heisenberg $J_1$-$J_2$ model, our results are better than those of the complex-valued CNN in the literature, implying that the sign structure of the complex-valued NQS is difficult to be optimized. We will study the optimization of the sign structure of NQSs in the future.

cond-mat.str-el↗

arXiv2023

Confirmation of a Sub-Saturn-size transiting exoplanet orbiting a G dwarf: TOI-1194 b and a very low mass companion star: TOI-1251 B from TESS

We report the confirmation of a sub-Saturn-size exoplanet, TOI-1194 b with a mass about $0.456_{-0.051}^{+0.055}$ $M_{J}$, and a very low mass companion star with a mass of about $96.5\pm1.5$ $M_J$, TOI-1251 B. Exoplanet candidates provided by the Transiting Exoplanet Survey Satellite (TESS) are suitable for further follow-up observations by ground-based telescopes with small and medium apertures. The analysis is performed based on data from several telescopes worldwide, including telescopes in the Sino-German multiband photometric campaign, which aimed at confirming TESS Objects of Interest (TOIs) using ground-based small-aperture and medium-aperture telescopes, especially for long-period targets. TOI-1194 b is confirmed based on the consistent periodic transits depths from the multiband photometric data. We measure an orbital period of $2.310644\pm0.000001$ d, and radius is $0.767_{-0.041}^{+0.045}$ $R_J$, and amplitude of RV curve is $69.4_{-7.3}^{+7.9}$ m/s. TOI-1251 B is confirmed based on the multiband photometric and high-resolution spectroscopic data, whose orbiting period is $5.963054_{-0.000001}^{+0.000002}$ d, the radius is $0.947_{-0.033}^{+0.035}$ $R_J$, and amplitude of RV curve is $9849_{-40}^{+42}$ m/s.

astro-ph.EP↗

arXiv2023

Optimized detector tomography for photon-number resolving detectors with hundreds of pixels

Photon-number resolving detectors with hundreds of pixels are now readily available, while the characterization of these detectors using detector tomography is computationally intensive. Here, we present a modified detector tomography model that reduces the number of variables that need optimization. To evaluate the effectiveness and accuracy of our model, we reconstruct the photon number distribution of optical coherent and thermal states using the expectation-maximization-entropy algorithm. Our results indicate that the fidelity of the reconstructed states remains above 99%, and the second and third-order correlations agree well with the theoretical values for a mean number of photons up to 100. We also investigate the computational resources required for detector tomography and find out that our approach reduces the solving time by around a half compared to the standard detector tomography approach, and the required memory resources are the main obstacle for detector tomography of a large number of pixels. Our results suggest that detector tomography is viable on a supercomputer with 1~TB RAM for detectors with up to 340 pixels.

quant-ph↗

arXiv2022

Nonlinear optical radiation of a lithium niobate microcavity

The nonlinear optical radiation of an integrated lithium niobate microcavity is demonstrated, which has been neglected in previous studies of nonlinear photonic devices. We find that the nonlinear coupling between confined optical modes on the chip and continuum modes in free space can be greatly enhanced on the platform of integrated microcavity, with feasible relaxation of the phase-matching condition. With an infrared pump laser, we observe the vertical radiation of second-harmonic wave at the visible band, which indicates a robust phase-matching-free chip-to-free-space frequency converter and also unveils an extra energy dissipation channel for integrated devices. Such an unexpected coherent nonlinear interaction between the free-space beam and the confined mode is also validated by the different frequency generation. Furthermore, based on the phase-matching-free nature of the nonlinear radiation, we build an integrated atomic gas sensor to characterize Rb isotopes with a single telecom laser. The unveiled mechanism of nonlinear optical radiation is universal for all dielectric photonic integrated devices, and provides a simple and robust chip-to-free-space as well as visible-to-telecom interface.

physics.optics↗

arXiv2022

Synthetic five-wave mixing in an integrated microcavity for visible-telecom entanglement generation

Nonlinear optics processes lie at the heart of photonics and quantum optics for their indispensable role in light sources and information processing. During the past decades, the three- and four-wave mixing ($χ^{(2)}$ and $χ^{(3)}$) effects have been extensively studied, especially in the micro-/nano-structures by which the photon-photon interaction strength is greatly enhanced. So far, the high-order nonlinearity beyond the $χ^{(3)}$ has rarely been studied in dielectric materials due to their weak intrinsic nonlinear susceptibility, even in high-quality microcavities. Here, an effective five-wave mixing process ($χ^{(4)}$) is synthesized for the first time, by incorporating $χ^{(2)}$ and $χ^{(3)}$ processes in a single microcavity. The coherence of the synthetic $χ^{(4)}$ is verified by generating time-energy entangled visible-telecom photon-pairs, which requires only one drive laser at the telecom waveband. The photon pair generation rate from the synthetic process shows an enhancement factor over $500$ times upon intrinsic five-wave mixing. Our work demonstrates a universal approach of nonlinear synthesis via photonic structure engineering at the mesoscopic scale rather than material engineering, and thus opens a new avenue for realizing high-order optical nonlinearities and exploring novel functional photonic devices.

quant-ph↗

arXiv2022

High-frequency traveling-wave phononic cavity with sub-micron wavelength

Thin-film gallium nitride (GaN) as a proven piezoelectric material is a promising platform for the phononic integrated circuits, which hold great potential for scalable information processing processors. Here, an unsuspended traveling phononic resonator based on high-acoustic-index-contrast mechanism is realized in GaN-on-Sapphire with a frequency up to 5 GHz, which matches the typical superconducting qubit frequency. A sixfold increment in quality factor was found when temperature decreases from room temperature ($Q=5000$) to $7\,\mathrm{K}$ ($Q=30000$) and thus a frequency-quality factor product of $1.5\times10^{14}$ is obtained. Higher quality factors are available when the fabrication process is further optimized. Our system shows great potential in hybrid quantum devices via circuit quantum acoustodynamics.

physics.app-ph↗

arXiv2020

Efficient frequency conversion in a degenerate $χ^{(2)}$ microresonator

Microresonators on a photonic chip could enhance nonlinear optics effects, thus are promising for realizing scalable high-efficiency frequency conversion devices. However, fulfilling phase matching conditions among multiple wavelengths remains a significant challenge. Here, we present a feasible scheme for degenerate sum-frequency conversion that only requires the two-mode phase matching condition. When the drive and the signal are both near resonance to the same telecom mode, an efficient on-chip photon-number conversion efficiency upto 42% was achieved, showing a broad tuning bandwidth over 250GHz. Furthermore, cascaded Pockels and Kerr nonlinear optical effects are observed, enabling the parametric amplification of the optical signal to a distinct wavelength in a single device. The scheme demonstrated in this work provides an alternative approach to realizing high-efficiency frequency conversion and is promising for future studies on communications, atom clocks, sensing, and imaging.

physics.optics↗