Quantum Superresolution
Quantum Superresolution
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We present a parameter-decoupled superresolution framework for estimating sub-wavelength separations of passive two-point sources without requiring prior knowledge or control of the source. Our theoretical foundation circumvents the need to estimate multiple challenging parameters such as partial coherence, brightness imbalance, random relative phase, and photon statistics. A physics-informed machine learning (ML) model (trained with a standard desktop workstation), synergistically integrating this theory, further addresses practical imperfections including background noise, photon loss, and centroid/orientation misalignment. The physics-informed parameter-decoupling ML model demonstrates significantly superior performance over conventional direct data-driven ML models. It achieves resolution 14 and more times below the diffraction limit (corresponding to ∼ 13.5 nm in optical microscopy) on experimentally generated realistic images with > 82% fidelity, performance rivaling state-of-the-art techniques for actively controllable sources. Critically, our method’s robustness against source parameter variability and source-independent noises enables potential applications in realistic scenarios where source control is infeasible, such as astrophysical imaging, live-cell microscopy, and quantum metrology. This work bridges a critical gap between theoretical superresolution limits and practical implementations for passive systems.
When two point sources are separated by less than the Abbe-Rayleigh limit, conventional resolution methods fail to distinguish whether there is one source or two. Consequently, it becomes nearly impossible to resolve important relative properties of the two sources, such as mutual coherence, relative phase, and brightness contrast. In this regime, the incoming composite quantum signal must be treated as a single entity described by an overall quantum wave function. In this study, we explore the superresolution of such two-point sources by examining a special wave property, i.e., entanglement between spatial degree of freedom (DoF) and remaining DoFs (both internal and external). Remarkably, we find that increasing this inter-DoF entanglement enhances the precision of superresolution, as quantified by the quantum Fisher information (QFI) in single-parameter estimation. Moreover, we show that this entanglement reliably ensures a nonvanishing QFI in two-parameter estimation, highlighting its role as a valuable resource for quantum superresolution.
Quantum Simulation with Classical Optics
Quantum Simulation with Classical Optics
Simulating dynamics of quantum harmonic oscillator with a propagating beam
We investigate the analogies between the time evolution of 2D harmonic oscillator and a propagating light beam. Experimental realizations of coherent state, squeezed state, and Schrodinger's cat state are achieved
Simulation of simplified Shor's factorization algorithm
We propose a novel algorithm that simplifies the Shor's algorithm with minimum required numbers of qubits. Experimental realization is acheived with a 3-qubit system simulated by classically entangled light beam.
Quantum Wave-Particle Duality
Quantum Wave-Particle Duality
We present a systematic framework to quantify the interplay between coherence and wave-particle duality in generic two-path interference systems. Our analysis reveals a closed-form duality ellipse (DE) equality, that rigorously unifies visibility (a traditional waveness measure) and predictability (a particleness measure) with degree of coherence, providing a complete mathematical embodiment of Bohr's complementarity principle. Extending this framework to quantum imaging with undetected photons (QIUP), where both path information and photon interference are inherently linked to spatial object reconstruction, we establish an imaging duality ellipse (IDE) that directly connects wave-particle duality to the object's transmittance profile. This relation enables object characterization through duality measurements alone and remains robust against experimental imperfections such as decoherence and misalignment. Our results advance the fundamental understanding of quantum duality while offering a practical toolkit for optimizing coherence-driven quantum technologies, from imaging to sensing.
Fundamentally contradictory but inescapably joined dual attributes, wave and particle, remain a conceptually unsettling element at the heart of quantum mechanics. It was a career-long unanswered challenge for Bohr to rationalize quantum duality. The conceptual dilemma it presents has remained an open issue, a topic of continued discussion, ever since. Here we report the discovery of an experimentally manageable route to control the weirdness of duality. Ironically, entanglement, the other conceptually challenging weirdness of quantum theory, will be shown to be in control of duality. We establish a simple identity through which entanglement prescribes quantitatively the degree of duality, of combined waveness and particleness, that can be recorded in any one-quantum two-path coherence experiment.
Quantum Magnonics
Quantum Magnonics
We present a systematic analysis of cavity effects on the decay dynamics of an open magnonic system. The Purcell effect on the magnon oscillator decay is thoroughly examined for both driven and nondriven scenarios with realistic parameters and initial conditions. Analytical conditions are determined to distinguish between strong and weak coupling regimes, corresponding to oscillatory and pure decay behaviors, respectively. Additionally, our theory predicts the decay of the photon mode within the cavity-magnonic open system, demonstrating excellent agreement with existing experimental data. Our findings and methodologies provide valuable insights for advancing research in cavity magnonic quantum control, quantum information processing, and the development of magnonic quantum devices.
We investigate dynamical generation of macroscopic nonlocal entanglements between two remote massive magnon–superconducting-circuit hybrid systems. Two fiber-coupled microwave cavities are employed to serve as an interaction channel connecting two sets of macroscopic hybrid units, each containing a magnon (hosted by an yttrium–iron–garnet sphere) and a superconducting-circuit qubit. Surprisingly, it is found that stronger coupling does not necessarily mean faster entanglement generation. The proposed hybrid system allows the existence of an optimal fiber coupling strength that requires the shortest amount of time to generate a systematic maximal entanglement. Our theoretical results are shown to be within the scope of specific parameters that can be achieved with current technology. The noise effects on the implementation of systems are also treated in a general environment, suggesting the robustness of entanglement generation. Our discrete-variable qubit-like entanglement theory of magnons may lead to direct applications in various quantum information tasks.
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