arXiv subjects

Chuanlong Ma

Publications and source records attributed to Chuanlong Ma.

8 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

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↗

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

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

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

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↗