Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Quantum 2.0 Conference and Exhibition

Complexity from genuine non-Gaussian entanglement: quantum correlations beyond Hong-Ou-Mandel

Xiaobin Zhao, Pengcheng Liao, Quntao Zhuang

Published Jan 1, 2025• 0 citations
Publisher

Abstract

Quantum state tomography requires exponential copies due to complex correlations. Generalizing the Hong-Ou-Mandel effect, we establish a resource theory for non-Gaussian entanglement, showing polynomial scaling for learning free states and exponential scaling for resource states. .
DOI
10.1364/quantum.2025.qtu4a.7

Related papers

Certification of genuine non-Gaussian entanglement

Lukáš Lachman, Carlos E. Lopetegui-González, Massimo Frigerio +1 more

Entanglement is a key resource for many quantum applications. Understanding fundamental properties of entangled states is an important step towards their practical exploitation. We characterize entanglement in the context of Gaussian and non-Gaussian processes and identify entangled states that cannot be produced by any Gaussian evolution acting on separable states. This distinction exposes intrinsic limitations of Gaussian operations and highlights the role of non-Gaussian operations as an important resource. We apply this framework to develop a certification method that connects entanglement theory with quantum non-Gaussianity - an advanced quantum feature that is essential for several quantum applications. Our approach tailors the certification to experimentally relevant states that can be produced in current quantum optics experiments. We demonstrate this certification for recognizing the genuine non-Gaussian entanglement of various entangled Fock states and hybrid entangled states.

quant-pharXiv:2604.22295•Apr 27, 2026•0 citations

Complexity of quantum tomography from genuine non-Gaussian entanglement

Xiaobin Zhao, Pengcheng Liao, Francesco Anna Mele +2 more

Quantum state tomography typically requires exponentially many copies of a quantum state, due to the complex correlations present in large systems. We show that, for bosonic systems, the scaling is completely determined by the nature of these correlations. Motivated by the Hong-Ou-Mandel effect and boson sampling, we define Gaussian-entanglable (GE) states, produced by generalized interference between separable bosonic modes. GE states greatly extend the Gaussian family, encompassing separable states, multi-mode Gottesman-Kitaev-Preskill codes, entangled cat states, and boson-sampling outputs-resources for error correction and quantum advantage. We prove that any pure GE state of m modes can be learned efficiently, requiring only poly(m) copies, via a protocol based on Gaussian unitaries, local tomography, and classical post-processing; for boson-sampling states, no Gaussian unitaries are needed. For states outside GE, we define an operational monotone-the minimal number of ancillary modes needed to make them GE-which exactly characterizes the exponential tomography overhead. We also show that deterministic generation of NOON states with N ≥ 3 via two-mode interference is impossible.

arXiv:2411.01609•Nature Communications•Dec 5, 2025•2 citations

Efficient learning of bosonic unitaries beyond the Gaussian class

Xiaobin Zhao, Quntao Zhuang

Multimode quantum processes are generally difficult to learn, due to the large dimensionality and complex entanglement structure beyond the Gaussian class. Here, we show that the fundamental obstruction is not non-Gaussianity itself, but the buildup of irreducible multimode non-Gaussian correlations. We establish a tractability frontier for bosonic unitary learning: a general $m$-mode unitary with input energy at most $E$ per mode requires at least $Ω(E^{2m})$ channel uses, whereas two broad non-Gaussian families---$t$-doped Gaussian unitaries and Gaussian-entanglable unitaries---can be learned with resources polynomial in $m$. The latter can exhibit both extensive non-Gaussianity and strong multimode entanglement. Our forward-only protocols use coherent-state probes, Gaussian operations, local heterodyne detection, and classical post-processing to identify the global Gaussian mixing and reduce the remaining task to single- or few-mode learning. The analysis also yields a multimode quantum Darmois--Skitovich theorem showing that mode-spreading passive networks preserve product structure only for Gaussian input states, an almost-sure activation theorem for non-Gaussian processes showing that non-Gaussian unitaries yield non-Gaussian outputs for almost all coherent input states, and a method for learning unitaries from uncalibrated coherent probes. Our results identify that complexity of learning arises from irreducible mixing of non-Gaussianity and entanglement, rather than either resource alone.

quant-pharXiv:2607.27534•Jul 31, 2026•0 citations

Quantum Nonlocally Correlated Observables for Non-Gaussian States

Hongrong Li, Fuli Li, Shi-Yao Zhu

Quantum nonlocally correlated observables of the squeezed Bell-like states are investigated. We find that the higher amount of the entanglement does not always mean the stronger correlation of positions and momentums in the non-Gaussian states such as the photon-added states and the squeezed number states. Quantum nonlocal correlations of the amplitude-squared operators signal the entanglement existence of all the squeezed Bell-like states.

Chinese Physics Letters•May 1, 2011•1 citation

Universal entanglement-inspired correlations

Elizabeth Agudelo, Laura Ares, Jan Sperling

Quantum correlations, crucial for the advantage and advancement of quantum science and technology, arise from the impossibility of expressing a quantum state as a tensor product over a given set of parties. In this work, a generalized notion of correlations via arbitrary products is formulated. Remarkably, as a universal property, the connection between such general products and tensor products is established, allowing one to relate generic non-product states to the common notion of entangled states. We construct the set of free operations for general types of products by extending the local-operation-and-classical-communication paradigm, familiar from standard entanglement theory, thereby establishing a resource theory of correlations for general products. A generalization is provided beyond two factors that can be universally related to multipartite entanglement. Applications that highlight the usefulness of the approach are discussed, such as the factorization of fermionic states, the non-local factorization of multi-photon states into single-photon states, and the interesting possibility of understanding prime numbers as a form of single-party entanglement.

quant-pharXiv:2602.15520•Feb 18, 2026•0 citations

Quantum Entanglement States: A Non-Local Theory

Jincheng Zhang

Quantum entanglement, a cornerstone of quantum mechanics, presents a profound challenge to classical intuition. This paper explores the potential of extending this peculiar phenomenon to encompass non-local correlations, proposing a novel framework termed "Entanglement Non-Locality" (ENL). The core claim is to establish a theoretical foundation for this non-locality, leveraging the inherent properties of entangled states to simulate quantum information transfer and associate it with classical information transfer. We hypothesize that by embedding entanglement within a non-local field theory, we can achieve enhanced quantum information processing and communication capabilities. This research delves into the design of such a field theory, examining its potential to overcome limitations imposed by classical physics and unlock new avenues for quantum technologies.

•Sep 7, 2026•0 citations
Entanglement is a key resource for many quantum applications. Understanding fundamental properties of entangled states is an important step towards their practical exploitation. We characterize entanglement in the context of Gaussian and non-Gaussian processes and identify entangled states that cannot be produced by any Gaussian evolution acting on separable states. This distinction exposes intrinsic limitations of Gaussian operations and highlights the role of non-Gaussian operations as an important resource. We apply this framework to develop a certification method that connects entanglement theory with quantum non-Gaussianity - an advanced quantum feature that is essential for several quantum applications. Our approach tailors the certification to experimentally relevant states that can be produced in current quantum optics experiments. We demonstrate this certification for recognizing the genuine non-Gaussian entanglement of various entangled Fock states and hybrid entangled states.
Quantum state tomography typically requires exponentially many copies of a quantum state, due to the complex correlations present in large systems. We show that, for bosonic systems, the scaling is completely determined by the nature of these correlations. Motivated by the Hong-Ou-Mandel effect and boson sampling, we define Gaussian-entanglable (GE) states, produced by generalized interference between separable bosonic modes. GE states greatly extend the Gaussian family, encompassing separable states, multi-mode Gottesman-Kitaev-Preskill codes, entangled cat states, and boson-sampling outputs-resources for error correction and quantum advantage. We prove that any pure GE state of m modes can be learned efficiently, requiring only poly(m) copies, via a protocol based on Gaussian unitaries, local tomography, and classical post-processing; for boson-sampling states, no Gaussian unitaries are needed. For states outside GE, we define an operational monotone-the minimal number of ancillary modes needed to make them GE-which exactly characterizes the exponential tomography overhead. We also show that deterministic generation of NOON states with N ≥ 3 via two-mode interference is impossible.
Multimode quantum processes are generally difficult to learn, due to the large dimensionality and complex entanglement structure beyond the Gaussian class. Here, we show that the fundamental obstruction is not non-Gaussianity itself, but the buildup of irreducible multimode non-Gaussian correlations. We establish a tractability frontier for bosonic unitary learning: a general mmm-mode unitary with input energy at most EEE per mode requires at least Ω(E2m)Ω(E^{2m})Ω(E2m) channel uses, whereas two broad non-Gaussian families---ttt-doped Gaussian unitaries and Gaussian-entanglable unitaries---can be learned with resources polynomial in mmm. The latter can exhibit both extensive non-Gaussianity and strong multimode entanglement. Our forward-only protocols use coherent-state probes, Gaussian operations, local heterodyne detection, and classical post-processing to identify the global Gaussian mixing and reduce the remaining task to single- or few-mode learning. The analysis also yields a multimode quantum Darmois--Skitovich theorem showing that mode-spreading passive networks preserve product structure only for Gaussian input states, an almost-sure activation theorem for non-Gaussian processes showing that non-Gaussian unitaries yield non-Gaussian outputs for almost all coherent input states, and a method for learning unitaries from uncalibrated coherent probes. Our results identify that complexity of learning arises from irreducible mixing of non-Gaussianity and entanglement, rather than either resource alone.
Quantum correlations, crucial for the advantage and advancement of quantum science and technology, arise from the impossibility of expressing a quantum state as a tensor product over a given set of parties. In this work, a generalized notion of correlations via arbitrary products is formulated. Remarkably, as a universal property, the connection between such general products and tensor products is established, allowing one to relate generic non-product states to the common notion of entangled states. We construct the set of free operations for general types of products by extending the local-operation-and-classical-communication paradigm, familiar from standard entanglement theory, thereby establishing a resource theory of correlations for general products. A generalization is provided beyond two factors that can be universally related to multipartite entanglement. Applications that highlight the usefulness of the approach are discussed, such as the factorization of fermionic states, the non-local factorization of multi-photon states into single-photon states, and the interesting possibility of understanding prime numbers as a form of single-party entanglement.
Quantum entanglement, a cornerstone of quantum mechanics, presents a profound challenge to classical intuition. This paper explores the potential of extending this peculiar phenomenon to encompass non-local correlations, proposing a novel framework termed "Entanglement Non-Locality" (ENL). The core claim is to establish a theoretical foundation for this non-locality, leveraging the inherent properties of entangled states to simulate quantum information transfer and associate it with classical information transfer. We hypothesize that by embedding entanglement within a non-local field theory, we can achieve enhanced quantum information processing and communication capabilities. This research delves into the design of such a field theory, examining its potential to overcome limitations imposed by classical physics and unlock new avenues for quantum technologies.