{"title":"Random Covariant Quantum Channels","authors":"Ion Nechita, Sang-Jun Park","doi":"10.1007/s00023-025-01558-y","DOIUrl":"10.1007/s00023-025-01558-y","url":null,"abstract":"<div><p>The group symmetries inherent in quantum channels often make them tractable and applicable to various problems in quantum information theory. In this paper, we introduce natural probability distributions for covariant quantum channels. Specifically, this is achieved through the application of “twirling operations” on random quantum channels derived from the Stinespring representation that uses Haar-distributed random isometries. We explore various types of group symmetries, including unitary and orthogonal covariance, hyperoctahedral covariance, and diagonal orthogonal covariance (DOC), and analyze their properties related to quantum entanglement based on the model parameters. In particular, we discuss the threshold phenomenon for positive partial transpose and entanglement breaking properties, comparing thresholds among different classes of random covariant channels. Finally, we contribute to the <span>(hbox {PPT}^2)</span> conjecture by showing that the composition between two random DOC channels is generically entanglement breaking.\u0000</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 3","pages":"847 - 907"},"PeriodicalIF":1.3,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00023-025-01558-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147441767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mean Eigenvector Self-Overlap in the Real and Complex Elliptic Ginibre Ensembles at Strong and Weak Non-Hermiticity","authors":"Mark J. Crumpton, Yan V. Fyodorov, Tim R. Würfel","doi":"10.1007/s00023-024-01530-2","DOIUrl":"10.1007/s00023-024-01530-2","url":null,"abstract":"<div><p>We study the mean diagonal overlap of left and right eigenvectors associated with complex eigenvalues in <span>(Ntimes N)</span> non-Hermitian random Gaussian matrices. In a well-known work by Chalker and Mehlig the expectation of this (self-)overlap was computed for the complex Ginibre ensemble as <span>(Nrightarrow infty )</span> (Chalker and Mehlig in Phys Rev Lett 81(16):3367–3370, 1998). In the present work, we consider the same quantity in the real and complex elliptic Ginibre ensembles, which are characterised by correlations between off-diagonal entries controlled by a parameter <span>(tau in [0,1])</span>, with <span>(tau =1)</span> corresponding to the Hermitian limit. We derive exact expressions for the mean diagonal overlap in both ensembles at any finite <i>N</i>, for any eigenvalue off the real axis. We further investigate several scaling regimes as <span>(Nrightarrow infty )</span>, both in the limit of strong non-Hermiticity keeping a fixed <span>(tau in [0,1))</span> and in the weak non-Hermiticity limit, with <span>(tau )</span> approaching unity in such a way that <span>(N(1-tau ))</span> remains finite.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"26 6","pages":"2069 - 2116"},"PeriodicalIF":1.3,"publicationDate":"2025-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00023-024-01530-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145167319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the Diffusion Approximation of the Stationary Radiative Transfer Equation with Absorption and Emission","authors":"Elena Demattè, Juan J. L. Velázquez","doi":"10.1007/s00023-025-01556-0","DOIUrl":"10.1007/s00023-025-01556-0","url":null,"abstract":"<div><p>In this paper, we study the distribution of temperature of a body due to the transfer of radiation. Specifically, the boundary value problem for the stationary radiative transfer equation is considered. In all the analysis, we assume the so-called local thermal equilibrium (LTE), i.e., there is a well-defined temperature of the body at each point. We consider the limit in which the mean free path of the photons is much smaller than the characteristic length of the domain. In this case, we can approximate the solution by means of the so-called diffusion approximation. The analysis of this paper is restricted to the case in which the absorption coefficient is independent of the frequency <span>( nu )</span> (the so-called Grey approximation). We ignore also scattering effects. Under these assumptions, we show that the density of radiative energy <i>u</i>, which is proportional to the fourth power of the temperature, solves in the limit an elliptic equation. The boundary values for that limit equation can be determined uniquely analyzing a suitable boundary layer problem. The method developed here allows to prove all the results using maximum principle arguments for a class of non-local elliptic equations.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 3","pages":"1075 - 1163"},"PeriodicalIF":1.3,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00023-025-01556-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147441472","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Local Time Decay for Fractional Schrödinger Operators with Slowly Decaying Potentials","authors":"Kouichi Taira","doi":"10.1007/s00023-025-01560-4","DOIUrl":"10.1007/s00023-025-01560-4","url":null,"abstract":"<div><p>A local time decay estimate of fractional Schrödinger operators with slowly decaying positive potentials is studied. It is shown that the resolvent is smooth near zero, and the time propagator exhibits fast local time decay, which is very different from very short-range cases. The key element of the proof is to establish a weaker Agmon estimate for a classically forbidden region using exotic symbol calculus. As a byproduct, we prove that the Riesz operator is a pseudodifferential operator with an exotic symbol.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 2","pages":"691 - 730"},"PeriodicalIF":1.3,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147339556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Examples of Small-Time Controllable Schrödinger Equations","authors":"Karine Beauchard, Eugenio Pozzoli","doi":"10.1007/s00023-025-01559-x","DOIUrl":"10.1007/s00023-025-01559-x","url":null,"abstract":"<div><p>A variety of physically relevant bilinear Schrödinger equations are known to be approximately controllable in large times. There are, however, examples, which are approximately controllable in large times, but not in small times. This obstruction happens, for example, in the presence of (sub)quadratic potentials, because Gaussian states are preserved, at least for small times. In this work, we provide the first examples of small-time approximately controllable bilinear Schrödinger equations. In particular, we show that a control on the frequency of a quadratic potential permits to construct approximate solutions that evolve arbitrarily fast along space-dilations. Once we have access to space-dilations, we can exploit them to generate time-contractions. In this way, we build on previous results of large-time control, to obtain control in small times.\u0000</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 2","pages":"757 - 786"},"PeriodicalIF":1.3,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147339305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Quenched Large Deviations of Birkhoff Sums Along Random Quantum Measurements","authors":"R. Raquépas, J. Schenker","doi":"10.1007/s00023-025-01553-3","DOIUrl":"10.1007/s00023-025-01553-3","url":null,"abstract":"<div><p>We prove a quenched version of the large deviation principle for Birkhoff-like sums along a sequence of random quantum measurements driven by an ergodic process. We apply the result to the study of entropy production in the two-time measurement framework.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 2","pages":"731 - 755"},"PeriodicalIF":1.3,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147338637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Order p Quantum Wasserstein Distances from Couplings","authors":"Emily Beatty, Daniel Stilck França","doi":"10.1007/s00023-025-01557-z","DOIUrl":"10.1007/s00023-025-01557-z","url":null,"abstract":"<div><p>Optimal transport provides a powerful mathematical framework with applications spanning numerous fields. A cornerstone within this domain is the <i>p</i>-Wasserstein distance, which serves to quantify the cost of transporting one probability measure to another. While recent attempts have sought to extend this measure to the realm of quantum states, existing definitions often present certain limitations, such as not being faithful. In this work, we present a new definition of quantum Wasserstein distances. This definition, leveraging the coupling method and a metric applicable to pure states, draws inspiration from a property characterising the classical Wasserstein distance—its determination based on its value on point masses. Subject to certain continuity properties, our definition exhibits numerous attributes expected of an optimal quantum rendition of the Wasserstein distance. Notably, our approach seamlessly integrates metrics familiar to quantum information theory, such as the trace distance. Moreover, it provides an organic extension for metrics, like Nielsen’s complexity metric, allowing their application to mixed states with a natural operational interpretation. We analyse this metric’s attributes in the context of random quantum states, unveil phase transitions concerning the complexity of subsystems of random states and use it to derive circuit lower bounds. In addition, we show how we can use our definition to study hypercontractive inequalities for quantum channels that do not admit a faithful fixed point, allowing us to derive concentration inequalities. Finally, we discuss how our distance is well suited to define quantum Wasserstein generative adversarial networks.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 3","pages":"787 - 845"},"PeriodicalIF":1.3,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147441163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jeroen S. W. Lamb, Giuseppe Tenaglia, Dmitry Turaev
{"title":"Horseshoes for a Class of Nonuniformly Expanding Random Circle Maps","authors":"Jeroen S. W. Lamb, Giuseppe Tenaglia, Dmitry Turaev","doi":"10.1007/s00023-025-01555-1","DOIUrl":"10.1007/s00023-025-01555-1","url":null,"abstract":"<div><p>We propose a notion of random horseshoe for one-dimensional random dynamical systems with non-uniform expansion, and we provide sufficient conditions that guarantee their abundant existence, which is shown to hold for a class of non-uniformly expanding random circle endomorphisms with bounded additive noise.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 3","pages":"995 - 1032"},"PeriodicalIF":1.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00023-025-01555-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147440829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Thibault Bonnemain, Vincent Caudrelier, Benjamin Doyon
{"title":"Hamiltonian Formulation and Aspects of Integrability of Generalised Hydrodynamics","authors":"Thibault Bonnemain, Vincent Caudrelier, Benjamin Doyon","doi":"10.1007/s00023-025-01546-2","DOIUrl":"10.1007/s00023-025-01546-2","url":null,"abstract":"<div><p>Generalised hydrodynamics (GHD) describes the large-scale inhomogeneous dynamics of integrable (or close to integrable) systems in one dimension of space, based on a central equation for the fluid density or quasi-particle density: the GHD equation. We consider a new, general form of the GHD equation: we allow for spatially extended interaction kernels, generalising previous constructions. We show that the GHD equation, in our general form and hence also in its conventional form, is Hamiltonian. This holds also including force terms representing inhomogeneous external potentials coupled to conserved densities. To this end, we introduce a new Poisson bracket on functionals of the fluid density, which is seen as our dynamical field variable. The total energy is the Hamiltonian whose flow under this Poisson bracket generates the GHD equation. The fluid density depends on two (real and spectral) variables, and the GHD equation can be seen as a <span>(2+1)</span>-dimensional classical field theory. In its <span>(1+1)</span>-dimensional reduction corresponding to the case without external forces, we further show the system admits an infinite set of conserved quantities that are in involution for our Poisson bracket, hinting at integrability of this field theory.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"27 1","pages":"287 - 345"},"PeriodicalIF":1.3,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00023-025-01546-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145948096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ergodic and Non-Ergodic Phenomena in One-Dimensional Random Processes: Exploring Unconventional State Transitions","authors":"A. D. Ramos, C. S. Sousa, L. P. Cavalcanti","doi":"10.1007/s00023-025-01554-2","DOIUrl":"10.1007/s00023-025-01554-2","url":null,"abstract":"<div><p>Traditionally, the evolution of interacting particle systems has been based on an assumption that only the individual components undergo state changes. However, this rigid assumption is not the only possibility. This research explored a class of one-dimensional random processes that evolved in discrete time. During each time step, components in the state zero exhibited the following transitions. First, they could change to one with a probability <span>(beta _0)</span>. Second, they could be replaced by a sequence of <i>k</i> consecutive zeros with a probability <span>(beta _k)</span> (where <span>(k=1,ldots ,n)</span>). Moreover, these transitions occurred independent of the events occurring elsewhere in the involved system. Notably, this study revealed an unexpected phenomenon—the occurrence of a first-order phase transition between ergodic and non-ergodic behaviors within this system. Furthermore, in the non-ergodic regime, the existence of an invariant measure distinct from the trivial one was demonstrated.</p></div>","PeriodicalId":463,"journal":{"name":"Annales Henri Poincaré","volume":"26 8","pages":"3055 - 3073"},"PeriodicalIF":1.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145170865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}