arXiv subjects

Weiting Wang

Publications and source records attributed to Weiting Wang.

At least 19 recordsLinked to original sources

arXiv2026

Experimental realization of quantum-computing-enhanced sensing

Quantum algorithms offer computational advantages, yet incorporating them into quantum sensing and converting these advantages into enhanced information acquisition remains challenging. Here, we realize quantum-computing-enhanced sensing in a spin-oscillator architecture, where a microwave cavity provides a high-dimensional quantum register and a coupled superconducting qubit serves as the sensor. The unknown signal directly generates the phase oracle operation, establishing a natural physical interface between quantum computation and sensing. We experimentally demonstrate the first Grover search in a bosonic mode and observe quantum amplitude amplification in a Hilbert space spanning more than 128 photons. For the same number of sensing iterations, our protocol extracts more information and resolves more frequency candidates than classical sequential search. Our results establish signal-driven oracles as a route for harnessing oracle-based quantum algorithms and realizing quantum-computing-enhanced sensing.

quant-ph↗

arXiv2026

Magnetic-free optical mode degeneracy lifting in lithium niobate microring resonators

Breaking time-reversal symmetry in integrated photonics without magnetic fields remains a fundamental challenge. We demonstrate phonon-induced non-reciprocity through direct lifting of forward-backward mode degeneracy in microring resonators. Coherent acousto-optic coupling generates differential AC Stark shifts between counter-propagating fundamental optical modes, eliminating the need for intermodal conversion or complex photonic structures. Simple microwave excitation of integrated piezoelectric transducers provides dynamic control of non-reciprocal response, with experimentally demonstrated mode splitting exceeding twice the optical linewidth. The linear relationship between the splitting and acoustic power enables real-time reconfigurability across a wide range of optical wavelengths. This mechanism requires only simple microring resonators and fundamental optical modes, transforming non-reciprocity from a specialized technique requiring careful modal engineering to a universal, electrically-controlled functionality. Our approach establishes a new paradigm for magnetic-free optical isolation and dynamic topological photonics.

physics.optics↗

arXiv2026

Experimental demonstration of entanglement pumping with bosonic logical qubits

Entanglement is crucial for quantum networks and computation, yet maintaining high-fidelity entangled quantum states is hindered by decoherence and resource-intensive purification methods. Here, we experimentally demonstrate entanglement pumping, utilizing bosonic quantum error correction (QEC) codes as long-coherence-time storage qubits. By repetitively generating entanglement with short-coherence-time qubits and injecting it into error-detectable logical qubits, our approach effectively preserves entanglement. Through error-detection to discard error states and entanglement pumping to mitigate errors within the code space, we extend the existence time of entanglement by nearly 50% compared to the case without entanglement pumping. This entanglement pumping scheme can additionally serve as an erasure detection protocol for the dual-rail code. This work highlights the potential of bosonic logical qubits for scalable quantum networks and introduces a novel paradigm for efficient entanglement management.

quant-ph↗

arXiv2026

Robust and optimal control of open quantum systems

Recent advancements in quantum technologies have highlighted the importance of mitigating system imperfections, including parameter uncertainties and decoherence effects, to improve the performance of experimental platforms. However, most of the previous efforts in quantum control are devoted to the realization of arbitrary unitary operations in a closed quantum system. Here, we improve the algorithm that suppresses system imperfections and noises, providing notably enhanced scalability for robust and optimal control of open quantum systems. Through experimental validation in a superconducting quantum circuit, we demonstrate that our approach outperforms its conventional counterpart for closed quantum systems with an ultra-low infidelity of about $0.60\%$, while the complexity of this algorithm exhibits the same scaling, with only a modest increase in the prefactor. This work represents a notable advancement in quantum optimal control techniques, paving the way for realizing quantum-enhanced technologies in practical applications.

quant-ph↗

arXiv2026

Quantum Confocal Microscopy in Fock Space with a 19 dB Metrological Gain

Quantum metrology promises measurement precision beyond classical limits by exploiting large-scale quantum states, yet realizing this advantage faces two fundamental challenges: the deterministic preparation of non-trivial quantum probes and the efficient extraction of metrological information in high-dimensional Hilbert spaces. Here, we introduce quantum confocal microscopy in Fock space that simultaneously resolves both challenges. Drawing a direct analogy between classical wave optics and quantum state evolution in a bosonic mode, we construct a confocal system with two Fock-space lenses. The first lens deterministically focuses a coherent state into a quantum probe with a tightly concentrated photon-number distribution, while the second lens maps the metrological information back to the vacuum state for efficient readout. Using a superconducting circuit QED platform, we prepare focused probe states with mean photon numbers up to ${N} = 500$, achieving a 21.5$\pm$1.1 dB compression of the photon-number uncertainty relative to a coherent state, with a scalable quantum circuit of $\mathcal{O}(1)$ operational depth. We demonstrate a displacement sensitivity scaling as $N^{-0.416}$, approaching the Heisenberg scaling ($N^{-0.5}$), and achieve a record metrological gain of 19.06$\pm$0.13 dB beyond the standard quantum limit. This work establishes quantum confocal microscopy as a scalable and practical framework for quantum-enhanced precision measurement, readily extendable to other bosonic platforms and high-dimensional quantum many-body systems.

quant-ph↗

arXiv2026

Principles of Optics in the Fock Space: Scalable Manipulation of Giant Quantum States

The manipulation of distinct degrees of freedom of photons plays a critical role in both classical and quantum information processing. While the principles of wave optics provide elegant and scalable control over classical light in spatial and temporal domains, engineering quantum states in Fock space has been largely restricted to few-photon regimes, hindered by the computational and experimental challenges of large Hilbert spaces. Here, we introduce ``Fock-space optics", establishing a conceptual framework of wave propagation in the quantum domain by treating photon number as a synthetic dimension. Using a superconducting microwave resonator, we experimentally demonstrate Fock-space analogues of optical propagation, refraction, lensing, dispersion, and interference with up to 180 photons. These results establish a fundamental correspondence between Schrödinger evolution in a single bosonic mode and classical paraxial wave propagation. By mapping intuitive optical concepts onto high-dimensional quantum state engineering, our work opens a path toward scalable control of large-scale quantum systems with thousands of photons and advanced bosonic information processing.

quant-ph↗

arXiv2025

High-performance quantum interconnect between bosonic modules beyond transmission loss constraints

Distributed quantum computing architectures require high-performance quantum interconnects between quantum information processing units, while previous implementations have been fundamentally limited by transmission line losses. Here, we demonstrate a low-loss interconnect between two superconducting modules using an aluminum coaxial cable, achieving a bus mode quality factor of 1.7e6. By employing SNAIL as couplers, we realize inter-modular state transfer in 0.8 μs via a three-wave mixing process. The state transfer fidelity reaches 98.2% for quantum states encoded in the first two energy levels, achieving a Bell state fidelity of 92.5%. Furthermore, we show the capability to transfer high-dimensional states by successfully transmitting binomially encoded logical states. Systematic characterization reveals that performance constraints have shifted from transmission line losses (contributing merely 0.2% infidelity) to module-channel interface effects and local Kerr nonlinearities. Our work advances the realization of quantum interconnects approaching fundamental capacity limits, paving the way for scalable distributed quantum computing and efficient quantum communications.

quant-ph↗

arXiv2025

All-optical control and multiplexed readout of multiple superconducting qubits

Superconducting quantum circuits operate at millikelvin temperatures, typically requiring independent microwave cables for each qubit for connecting room-temperature control and readout electronics. However, scaling to large-scale processors hosting hundreds of qubits faces a severe input/output (I/O) bottleneck, as the dense cable arrays impose prohibitive constraints on physical footprint, thermal load, wiring complexity, and cost. Here we demonstrate a complete optical I/O architecture for superconducting quantum circuits, in which all control and readout signals are transmitted exclusively via optical photons. Employing a broadband traveling-wave Brillouin microwave-to-optical transducer, we achieve simultaneous frequency-multiplexed optical readout of two qubits. Combined with fiber-integrated photodiode arrays for control signal delivery, this closed-loop optical I/O introduces no measurable degradation to qubit coherence times, with an optically driven single-qubit gate fidelity showing only a 0.19% reduction relative to standard microwave operation. These results establish optical interconnects as a viable path toward large-scale superconducting quantum processors, and open the possibility of networking multiple superconducting quantum computers housed in separate dilution refrigerators through a centralized room-temperature control infrastructure.

quant-ph↗

arXiv2025

Giant-atom quantum acoustodynamics in hybrid superconducting-phononic integrated circuits

We demonstrate a giant atom by coupling a superconducting transmon qubit to a lithium niobate phononic waveguide at two points separated by about 600 acoustic wavelengths, with a propagation delay of 125 ns. The giant atom yields non-Markovian relaxation dynamics characterized by phonon backflow and a frequency-dependent effective decay rate varying four-fold over merely 4 MHz, corresponding to a Purcell factor exceeding 40. Exploiting this frequency-dependent dissipation, we prepare quantum superposition states with high purity. Our results establish phononic integrated circuits as a versatile platform for giant-atom physics, providing highly tunable quantum devices for advanced quantum information processing.

quant-ph↗

arXiv2025

Scalable Optical Links for Controlling Bosonic Quantum Processors

Superconducting quantum computing has the potential to revolutionize computational capabilities. However, scaling up large quantum processors is limited by the cumbersome and heat-conductive electronic cables that connect room-temperature control electronics to quantum processors, leading to significant signal attenuation. Optical fibers provide a promising solution, but their use has been restricted to controlling simple two-level quantum systems over short distances. Here, we demonstrate optical control of a bosonic quantum processor, achieving universal operations on the joint Hilbert space of a transmon qubit and a storage cavity. Using an array of cryogenic fiber-integrated uni-traveling-carrier photodiodes, we prepare Fock states containing up to ten photons. Additionally, remote control of bosonic modes over a transmission distance of 15 km has been achieved, with fidelities exceeding 95%. The combination of high-dimensional quantum control, multi-channel operation, and long-distance transmission addresses the key requirements for scaling superconducting quantum computers and enables architectures for distributed quantum data centers.

quant-ph↗

arXiv2025

Circuit Quantum Acoustodynamics in a Scalable Phononic Integrated Circuit Architecture

Previous demonstrations of quantum acoustic systems have been limited to isolated devices, with limited capability to route phonons and interconnect multi-port acoustic elements for further extension. Here, we demonstrate a scalable architecture for circuit quantum acoustodynamics (cQAD) by integrating superconducting qubits with suspension-free phononic integrated circuits (PnICs). Coherent coupling between tunable transmon qubits and waveguide-integrated phononic cavities, including Fabry-Perot cavities via monolithic integration and microring cavities via flip-chip assembly, has been achieved, producing a pronounced enhancement of phonon emission with a Purcell factor of ~19. These devices represent elementary building blocks for scalable phononic circuits, establishing the foundation for phonon-based quantum information processors and the testbed for novel quantum acoustic phenomena.

quant-ph↗

arXiv2025

Acoustically control of integrated optical microrings: from photonic molecule to Mobius strip

Microring resonators (MRRs) are fundamental building blocks of photonic integrated circuits, yet their dynamic reconfiguration has been limited to tuning refractive index or absorption. Here, we demonstrate acoustic control over optical path topology on a lithium niobate on sapphire platform. By launching gigahertz acoustic waves into a hybrid phononic-photonic waveguide, a dynamic Bragg mirror (DBM) is created within the optical path, coupling forward and backward propagating light. Employing a pair of coupled MRRs, we achieve strong coupling between supermodes of the photonic molecule with only milliwatt-level drive power, yielding a cooperativity of 2.46 per milliwatt. At higher power, DBM reflectivity up to 24% is achieved, revealing breakdowns of both the photonic molecule picture and perturbative coupled mode theory, indicating the transformation toward Mobius strip topology. Our work establishes a new dimension for controlling photonic devices, opening pathways toward fully reconfigurable photonic circuits through acoustic drive.

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

High-Fidelity Controlled-Phase Gate for Binomial Codes via Geometric Phase Engineering

High-fidelity two-logical-qubit gates are essential for realizing fault-tolerant quantum computation with bosonic codes, yet experimentally reported fidelities have rarely exceeded 90\%. Here, we propose a geometric phase engineering approach for implementing controlled-phase gates for binomially encoded logical qubits. This method leverages the structural simplicity of geometric drives to reduce the numerical optimization dimensionality while fully incorporating system nonlinearities, enabling fast and high-fidelity logical operations. As an example, we experimentally demonstrate a process fidelity of 97.4$\pm$0.8\% for a controlled-Z gate between two binomial codes, surpassing all previously reported two-logical-qubit gates in bosonic codes. This work demonstrates that geometric phase engineering provides an effective and experimentally feasible route to fast, high-fidelity logical operations in bosonic quantum processors.

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

Extending coherence time beyond break-even point using only drives and dissipation

Quantum error correction (QEC) aims to mitigate the loss of quantum information to the environment, which is a critical requirement for practical quantum computing. Existing QEC implementations heavily rely on measurement-based feedback, however, constraints on readout fidelity, hardware latency, and system complexity often limit both performance and scalability. Autonomous QEC (AQEC) seeks to overcome these obstacles by stabilizing logical codewords using introduced drives that provide coherent control and engineered dissipation. Here, we propose an AQEC protocol, derived from quantum channel simulation, that is applicable to arbitrary error-correcting codes. As a demonstration, we implement the protocol using a binomial code encoded in a long-lived bosonic mode (lifetime > 1ms), and extend the logical qubit coherence time to 1.04 times that of the best physical qubit in the system. This is the first experimental realization of an AQEC-protected bosonic logical qubit beyond the break-even point, proving that coherence time can indeed be extended by introducing only drives and dissipation. Our results highlight the performance and scalability potential of AQEC, marking an important step toward large-scale, universal quantum computing.

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↗