Quantum sensing and metrology have been intensively studied over the last several decades to surpass the fundamental shot-noise limit of classical systems and approach the Heisenberg limit. However, implementation of N00N-state-based quantum sensing has been severely constrained by the limited order N, intrinsically imperfect fringe visibility, and vulnerability to photon loss. Recently, the coherence de Broglie wavelength (CBW) has been proposed as an alternative method for achieving superresolution in a coherently coupled interferometer architecture, whose characteristics resemble those of photonic de Broglie wavelength (PBW) used in quantum sensing. Here, we experimentally demonstrate scalable CBW superresolution up to N=3, with near-perfect fringe visibility that is invariant to photon loss. The observed CBWs have the potential to enable a superresolution sensing platform even if it remains within the shot-noise limit.
Quantum sensing and metrology have been intensively studied over the last several decades to surpass the fundamental shot-noise limit of classical systems and approach the Heisenberg limit. However, implementation of N00N-state-based quantum sensing has been severely constrained by the limited order N, intrinsically imperfect fringe visibility, and vulnerability to photon loss. Recently, the coherence de Broglie wavelength (CBW) has been proposed as an alternative method for achieving superresolution in a coherently coupled interferometer architecture, whose characteristics resemble those of photonic de Broglie wavelength (PBW) used in quantum sensing. Here, we experimentally demonstrate scalable CBW superresolution up to N=3, with near-perfect fringe visibility that is invariant to photon loss. The observed CBWs have the potential to enable a superresolution sensing platform even if it remains within the shot-noise limit.
Abstract Quantum sensing and metrology have been intensively studied over the last several decades to surpass the fundamental shot-noise limit of classical systems and approach the Heisenberg limit. However, implementation of N00N-state-based quantum sensing has been severely constrained by the limited order N , intrinsically imperfect fringe visibility, and vulnerability to photon loss. Recently, the coherence de Broglie wavelength (CBW) has been proposed as an alternative method for achieving superresolution in a coherently coupled interferometer architecture, whose characteristics resemble those of the photonic de Broglie wavelength (PBW) used in quantum sensing. Here, we experimentally demonstrate scalable CBW superresolution up to N =3, with near-perfect fringe visibility that is invariant to photon loss. The observed CBWs have the potential to enable a superresolution sensing platform even if it remains within the shot-noise limit.
A quantum wavemetry scheme based on the coherence de Broglie wavelength (CBW) is proposed using an M coupled Mach Zehnder interferometer (MZI) architecture to achieve superresolution sensing and metrology. Although CBW does not attain the Heisenberg limit, it circumvents the key practical limitations of N00N state based quantum sensing, including restricted photon number N, reduced fringe visibility, and strong susceptibility to photon loss. The CBW approach enables loss tolerant operation with arbitrarily large M, while maintaining near unity fringe visibility. Fully compatible with coherence optics, the CBW scheme can be directly integrated into conventional wavemetry systems, providing both superresolution and enhanced sensitivity. A proof of principle experiment demonstrating CBW based superresolution is implemented using a Sagnac integrated round trip MZI structure for M=2, validating the feasibility of the proposed quantum wavemetry design.
Quantum sensing exploits nonclassical states of light, including multiphoton entangled states and squeezed states, to achieve superresolution and/or super-sensitivity. However, its practical implementation is constrained by state-generation complexity, photon loss, and detection efficiency. Here, we present a quantum-operator analysis of coherence de Broglie wavelength (CBW) in an anti-symmetrically coupled Mach-Zehnder interferometer (MZI) architecture and clarify the origin of its superresolution and enhanced phase sensitivity. The two-mode SU(2) structure of the MZI, represented by Pauli operators, shows that successive basis-realigned transformations produce an Nth-order unitary U^N(phi), yielding N-fold phase accumulation (1+cosNphi). The quantum-operator description is particularly significant at the single-photon level, where even a single photon undergoes the Nth-order unitary evolution through its coherent evolution in the two-mode state space. This differs from entanglement-based quantum sensing based on photonic de Broglie wavelength interferometry, where N-fold phase accumulation is associated with an N-photon entangled state. The same SU(2) transformation also applies to coherent classical fields, establishing a classical-quantum correspondence of the CBW phase evolution. Fisher-information analysis further shows that the architecture-induced phase transformation yields an order-dependent enhancement of phase sensitivity without increasing the photon number or statistical sampling. CBW therefore provides an architecture-controlled route to high-order interferometric superresolution, accompanied by enhanced phase sensitivity, with potential applications to fringe-counting wavemetry and Fourier-transform-based sensing.
Abstract Quantum sensing has drawn considerable attention as a means to overcome the fundamental limitations in classical sensing. In practice, however, quantum sensing has been strongly constrained by the photon loss, the achievable photon number N in N00N states, and by a finite squeezing level in squeezed states. These limitations are particularly critical to photon-loss-sensitive applications such as LiDAR as well as to general sensing platforms that require large effective N, such as ring-laser gyroscopes. Recently, fundamentally different sensing platforms have been reported to overcome both classical and quantum constraints in a practical regime. One such approach exploits the coherence de Broglie wavelength (CBW) realized in an anti-symmetrically coupled Mach-Zehnder interferometer (MZI) architecture. Here, a pure quantum mechanical analysis of the CBW is presented for a loss-free sensing mechanism of superresolution with enhanced sensitivity. A proof-of-principle demonstration of CBW is also presented.
N00N states-maximally path-entangled states of N photons-exhibit spatial interference patterns sharper than any classical interference pattern. This is known as superresolution. However, even given perfectly efficient number-resolving detectors, the detection efficiency of all previous measurements of such interference would decrease exponentially with the number of photons in the N00N state, often leading to the conclusion that N00N states are unsuitable for spatial measurements. A technique known as the "optical centroid measurement" has been proposed to solve this and has been experimentally verified for photon pairs; here we present the first extension beyond two photons, measuring the superresolution fringes of two-, three-, and four-photon N00N states. Moreover, we compare the N00N-state interference to the corresponding classical superresolution interference. Although both provide the same increase in spatial frequency, the visibility of the classical fringes decreases exponentially with the number of detected photons. Our work represents an essential step forward for quantum-enhanced measurements, overcoming what was believed to be a fundamental challenge to quantum metrology.
Although quantum sensing theoretically offers an N-fold fringe enhancement at the Heisenberg limit, its practical realization has been limited by the difficulty of achieving high-order N in N00N states. Furthermore, quantum sensing systems are highly vulnerable to losses, especially in remote target detection applications. To address these challenges, I introduce a novel approach that enables potentially unlimited, N-proportional superresolution for laser-based remote sensing, even in lossy environments. This method builds upon new physics of quantum sensing rooted in the wave nature of photons. In particular, it employs the intensity product of N-divided signals with N phase controls. As a result, this approach opens the door toward achieving unrestricted N-fold superresolution in the macroscopic regime - surpassing both classical sensors constrained by first-order intensity correlations and conventional quantum sensors limited by N00N state requirements.