Article
Physics, Multidisciplinary
Luca Innocenti, Lukas Lachman, Radim Filip
Summary: The article presents operational criteria for detecting nonclassicality of quantum states. These criteria can be implemented in experiments with different systems such as light, atoms, solid-state systems, and mechanical oscillators.
PHYSICAL REVIEW LETTERS
(2023)
Article
Biochemical Research Methods
Aris Paschalidis, Oliver Watson, Ozkan Aydemir, Robert Verity, Jeffrey Bailey
Summary: In malaria, individuals can be infected with multiple parasite strains. This study presents two new methods to directly estimate the complexity of infection (COI) using easily calculated measures. The methods were found to be computationally efficient and accurate compared to existing approaches. The global estimation of COI revealed significant differences between continents and a weak relationship with malaria prevalence.
PLOS COMPUTATIONAL BIOLOGY
(2023)
Article
Optics
Massimo Frigerio, Stefano Olivares, Matteo G. A. Paris
Summary: This article explores the conditional generation or influence of P-nonclassicality on one mode by Gaussian measurements on the other mode, introducing the concept of nonclassical steering (NS). It also discusses the necessary conditions for TMST to be nonclassically steerable and the time limit for achieving NS in the case of noisy propagation. Additionally, it generalizes the notion of NS to the full set of Gaussian states of two modes, recognizing weak and strong forms that may or may not imply entanglement.
Article
Physics, Multidisciplinary
Nicola Biagi, Martin Bohmann, Elizabeth Agudelo, Marco Bellini, Alessandro Zavatta
Summary: This article introduces a phase-space inequalities method for certifying nonclassicality of quantum states, and demonstrates its practicality and sensitivity through experiments. The results show that the inequality conditions can detect nonclassicality even in cases of high losses and where other methods fail to reveal it.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Stephan De Bievre
Summary: For quantum systems with a finite dimensional Hilbert space of states, the complete incompatibility of two observables is shown to be equivalent to the large support uncertainty of all states. The Kirkwood-Dirac quasiprobability distribution of a state, dependent on the choice of two observables, has emerged as a tool in quantum information theory for assessing nonclassical features of a state. When two observables are completely incompatible, only states with minimal support uncertainty can be considered as KD classical.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Yue Zhang, Boxuan Jing, Qiongyi He, Shunlong Luo
Summary: This paper investigates the nonclassicality in systems involving the interaction between a spin and a boson mode, and proposes a method for quantifying this nonclassicality. The fundamental properties of the quantifier are revealed and applied to the Dicke model.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2022)
Article
Quantum Science & Technology
Luca Innocenti, Lukas Lachman, Radim Filip
Summary: Experimentally certifying the nonclassicality of quantum states in an optimal and efficient way remains a fundamental challenge. This study introduces a novel approach that is directly applicable to experimental realities and demonstrates its superiority in various scenarios. The findings represent a significant milestone towards a complete characterization of detectable nonclassicality in experimental implementations.
NPJ QUANTUM INFORMATION
(2022)
Article
Agriculture, Multidisciplinary
Alexander G. Olenskyj, Brent S. Sams, Zhenghao Fei, Vishal Singh, Pranav Raja, Gail M. Bornhorst, J. Mason Earles
Summary: This study demonstrates the applicability of nondestructive proximal imaging combined with deep learning for yield estimation in vineyards. The results show that the end-to-end modeling approach can perform comparably to the object detection approach while eliminating the need for hand-labeling.
COMPUTERS AND ELECTRONICS IN AGRICULTURE
(2022)
Article
Physics, Multidisciplinary
B. Kuehn, W. Vogel, V Thiel, S. Merkouche, B. J. Smith
Summary: Measures of quantum properties are essential for understanding the differences between quantum and classical systems, and quantifying resources for quantum technologies. By comparing different filtered versions of the Glauber-Sudarshan P function, this study explores their ability to reveal nonclassical effects of light. It is shown that non-Gaussian filtered quasiprobabilities can uncover significant nonclassical effects even at low efficiencies.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Xiaohui Li, Shunlong Luo, Yue Zhang
Summary: In this study, we propose a simple approach to quantify the optical nonclassicality of an optical state by exploiting the decoherent effect of Gaussian noise channel. The approach is based on the Wick-ordered characteristic function and we present a family of quantifiers for single-mode bosonic nonclassicality, which have desirable properties. We further demonstrate the effectiveness of the quantifiers using several typical states and also discuss the generalization to multi-mode cases.
EUROPEAN PHYSICAL JOURNAL PLUS
(2022)
Article
Physics, Multidisciplinary
David R. M. Arvidsson-Shukur, Jacob Chevalier Drori, Nicole Yunger Halpern
Summary: The Kirkwood-Dirac (KD) distribution, discovered by Kirkwood in 1933 and Dirac in 1945, has undergone a recent renaissance and is being used to study nonclassicality across quantum physics. The distribution can exhibit nonclassical behavior through negative or nonreal elements, with negative elements indicating quantum information scrambling and potential metrological advantages. Noncommutation of operators alone is not sufficient to determine the nonclassicality of the KD distribution, and this work provides sufficient conditions and quantification for understanding and potentially engineering quantum advantages.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Physics, Multidisciplinary
Yue Zhang, Shunlong Luo
Summary: The text discusses how the quantum state of a bosonic field can be described using a density operator or Husimi function, and proposes using entropy excess as a quantifier of nonclassicality in these states. By analyzing the differences between classical and quantum Tsallis entropies, the nonclassicality of bosonic field states can be assessed, with a focus on the difference between Wehrl and von Neumann entropy as a significant indicator. This entropic approach sheds light on the nature of nonclassicality in a quantum optics context involving heterodyne measurement.
EUROPEAN PHYSICAL JOURNAL PLUS
(2021)
Article
Quantum Science & Technology
Jonatan Bohr Brask, Fabien Clivaz, Geraldine Haack, Armin Tavakoli
Summary: This article investigates the fundamental resources and nonclassical effects needed to generate entanglement in quantum thermal machines. The evaluation of generated entanglement is conducted through different types of interactions and resource supply, with specific examples and limitations provided.
Article
Physics, Multidisciplinary
Yue Zhang, Shuheng Liu, Boxuan Jing, Qiongyi He, Shunlong Luo
Summary: This article discusses the importance of nonclassical states in quantum optics and proposes a method to quantify nonclassicality using phase-space distribution. The effectiveness of this method is demonstrated by evaluating the nonclassicality of several typical states.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2022)
Article
Astronomy & Astrophysics
Michael Kopp, Vasileios Fragkos, Igor Pikovski
Summary: This paper investigates the quantum effect of squeezing caused by gravitational self-interactions in axionlike particles (ALPs). The onset of squeezing for a typical QCD axion occurs on a microsecond scale and increases over millennia. Therefore, the classical models based on the Schrodinger-Poisson equation cannot fully describe viable ALPs.
Article
Physics, Multidisciplinary
Jonas Haferkamp, Philippe Faist, Naga B. T. Kothakonda, Jens Eisert, Nicole Yunger Halpern
Summary: The complexity of quantum states, which is key in quantum computing and black hole theory, has been shown to grow linearly over time under random operations. This study investigates how the complexity of random quantum circuits increases by constructing unitary operations from random two-qubit quantum gates. It is proven that the complexity grows linearly until it saturates at a threshold that is exponentially related to the number of qubits.
Article
Physics, Mathematical
J. Haferkamp, F. Montealegre-Mora, M. Heinrich, J. Eisert, D. Gross, I Roth
Summary: Many quantum information protocols require the use of random unitaries, and unitary t-designs are often used as an alternative to Haar-random unitaries. In this work, we explore the non-Clifford resources needed to break the limitation of only being able to implement up to 3-designs with Clifford operations. We find that injecting a certain number of non-Clifford gates into a random Clifford circuit can produce an epsilon-approximate t-design, regardless of the system size. We also derive new bounds on the convergence time of random Clifford circuits to the t-th moment of the uniform distribution on the Clifford group.
COMMUNICATIONS IN MATHEMATICAL PHYSICS
(2023)
Article
Physics, Multidisciplinary
Wenqiang Zheng, Hengyan Wang, Rebecca Schmieg, Alan Oesterle, Eugene S. Polzik
Summary: Magnetic induction tomography (MIT) is a protocol that uses radio-frequency magnetic fields to sense conductive objects. It has applications in nondestructive testing across various fields. By combining MIT with conditional spin squeezing and stroboscopic backaction evasion, we propose and verify a quantum-enhanced version of MIT using atomic magnetometers as sensors. This quantum enhancement allows for increased sensitivity beyond the standard quantum limits in detecting conductive samples in one-dimensional quantum MIT.
PHYSICAL REVIEW LETTERS
(2023)
Article
Physics, Multidisciplinary
M. Hinsche, M. Ioannou, A. Nietner, J. Haferkamp, Y. Quek, D. Hangleiter, J. -P. Seifert, J. Eisert, R. Sweke
Summary: The task of learning a probability distribution from samples is common in the natural sciences. This study extensively characterizes the learnability of output distributions from local quantum circuits. The results show that Clifford circuit output distributions are efficiently learnable, but the injection of a single T gate makes density modeling task difficult. Additionally, generative modeling of universal quantum circuits is hard for any learning algorithm, classical or quantum, indicating no quantum advantage for probabilistic modeling tasks.
PHYSICAL REVIEW LETTERS
(2023)
Article
Multidisciplinary Sciences
Mohammadamin Tajik, Marek Gluza, Nicolas Sebe, Philipp Schuettelkopf, Federica Cataldini, Joao Sabino, Frederik Moller, Si-Cong Ji, Sebastian Erne, Giacomo Guarnieri, Spyros Sotiriadis, Jens Eisert, Jorg Schmiedmayer
Summary: We investigate signal propagation in a quantum field simulator of the Klein-Gordon model using two strongly coupled parallel one-dimensional quasi-condensates. We observe the propagation of correlations along sharp light-cone fronts by measuring local phononic fields after a quench. The curved propagation fronts and reflection at sharp edges are observed when the local atomic density is inhomogeneous. By comparing the data with theoretical predictions, we find agreement with curved geodesics of an inhomogeneous metric.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2023)
Article
Quantum Science & Technology
Johannes Jakob Meyer, Marian Mularski, Elies Gil-Fuster, Antonio Anna Mele, Francesco Arzani, Alissa Wilms, Jens Eisert
Summary: Variational quantum machine learning is a widely studied application of near-term quantum computers. This work explores how symmetries of the learning problem can be used to construct quantum learning models with symmetrical outcomes. By utilizing tools from representation theory, a standard gateset can be transformed into an equivariant gateset that respects the symmetries of the problem. The proposed methods are benchmarked on toy problems and show a substantial increase in generalization performance.
Review
Physics, Multidisciplinary
Dominik Hangleiter, Jens Eisert
Summary: Quantum random sampling is the main proposal to demonstrate the computational advantage of quantum computers over classical computers. Recent large-scale implementations of quantum random sampling have possibly surpassed the capabilities of existing classical hardware for simulation. This review comprehensively discusses the theoretical basis and practical implementation of quantum random sampling, as well as its classical simulation, and explores open questions and potential applications in the field.
REVIEWS OF MODERN PHYSICS
(2023)
Article
Multidisciplinary Sciences
J. Helsen, M. Ioannou, J. Kitzinger, E. Onorati, A. H. Werner, J. Eisert, I. Roth
Summary: With quantum computing devices becoming more complex, there is a need for tools that can provide precise diagnostic information about quantum operations. The authors propose a new approach that uses random gate sequences and native measurements followed by classical post-processing to estimate various gate set properties. They also discuss applications for optimizing quantum gates and diagnosing cross-talk. This research is important for the development and improvement of quantum computing devices.
NATURE COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
F. H. B. Somhorst, R. van der Meer, M. Correa Anguita, R. Schadow, H. J. Snijders, M. de Goede, B. Kassenberg, P. Venderbosch, C. Taballione, J. P. Epping, H. H. van den Vlekkert, J. Timmerhuis, J. F. F. Bulmer, J. Lugani, I. A. Walmsley, P. W. H. Pinkse, J. Eisert, N. Walk, J. J. Renema
Summary: This study demonstrates that in a unitarily evolving system, single-mode measurements can converge to a thermal state using photons in an integrated optical interferometer. The resolution to the paradox between unitary evolution and the second law of thermodynamics is the recognition that the global unitary evolution of a multi-partite quantum state causes local subsystems to evolve towards maximum-entropy states. The experiment utilizes a programmable integrated quantum photonic processor to manipulate quantum states and shows the potential of photonic devices for simulating non-Gaussian states.
NATURE COMMUNICATIONS
(2023)
Article
Quantum Science & Technology
Ingo Roth, Jadwiga Wilkens, Dominik Hangleiter, Jens Eisert
Summary: Extracting tomographic information about quantum states is crucial in developing high-precision quantum devices. This study shows that by exploiting the low-rank structure of quantum states, a scalable 'blind' tomography scheme can be achieved with a computationally efficient post-processing algorithm. The efficiency of the scheme is further improved by utilizing the sparse structure of the calibrations.
Article
Optics
Niklas Pirnay, Ryan Sweke, Jens Eisert, Jean-Pierre Seifert
Summary: Density modeling is the task of learning an unknown probability density function from samples, and it is a central problem in unsupervised machine learning. This research demonstrates that fault-tolerant quantum computers can offer a superpolynomial advantage over classical learning algorithms in a specific density modeling problem, assuming standard cryptographic assumptions. The results also provide insights for future distribution learning separations between quantum and classical learning algorithms, including the relationship between hardness results in supervised learning and distribution learning.
Article
Materials Science, Multidisciplinary
Philipp Schmoll, Augustine Kshetrimayum, Jan Naumann, Jens Eisert, Yasir Iqbal
Summary: We investigate the ground state of the spin S = 1/2 Heisenberg antiferromagnet on the shuriken lattice, and found that a valence bond crystal with resonances over length six loops emerges as the ground state, yielding the lowest reported estimate of the ground state energy for this model. We also study the model in the presence of an external magnetic field and find the emergence of 0, 1/3, and 2/3 magnetization plateaus, with the 1/3 and 2/3 plateau states respecting translation and point group symmetries and featuring loop-four plaquette resonances.
Article
Quantum Science & Technology
Konstantin Tiurev, Peter-Jan H. S. Derks, Joschka Roffe, Jens Eisert, Jan-Michael Reiner
Summary: This study develops topological surface codes adapted to known noise structures and investigates their performance with specific decoders. Experimental results show that this approach significantly improves error thresholds and reduces failure rates. Furthermore, the study reveals the importance of tailored surface codes in correcting local noise.
Article
Quantum Science & Technology
Jarn de Jong, Frederik Hahn, Jens Eisert, Nathan Walk, Anna Pappa
Summary: Sharing multi-partite quantum entanglement allows for diverse secure communication tasks. In this work, an anonymous CKA protocol for three parties is proposed, implemented in a highly practical network setting using a linear cluster state among quantum nodes. The protocol protects the identities of the participants and contributes to identifying feasible quantum communication tasks for network architectures beyond point-to-point.
Article
Optics
Kevin Schultz, Ryan LaRose, Andrea Mari, Gregory Quiroz, Nathan Shammah, B. David Clader, William J. Zeng
Summary: In the presence of time-correlated noise, zero-noise extrapolation is less effective in reducing noise as it is difficult to scale noise levels without modifying its spectral distribution. However, global noise-scaling methods, such as global unitary folding, can still be reliable even in the presence of time-correlated noise.
