{"title":"On Single-Frequency Asymptotics for the Maxwell–Bloch Equations: Pure States","authors":"A. I. Komech, E. A. Kopylova","doi":"10.1007/s00220-026-05558-9","DOIUrl":"10.1007/s00220-026-05558-9","url":null,"abstract":"<div><p>We consider damped driven Maxwell–Bloch equations for a single-mode Maxwell field coupled to a two-level molecule. The equations are used for semiclassical description of the laser action. Our main result is the construction of solutions with single-frequency asymptotics of the Maxwell field in the case of quasiperiodic pumping. The asymptotics hold for solutions with harmonic initial values which are stationary states of averaged reduced equations in the interaction picture. We calculate all harmonic states and analyse their stability. Our calculations rely on the Hopf reduction by the gauge symmetry group <i>U</i>(1). The asymptotics follow by application of the averaging theory of Bogolyubov–Eckhaus–Sanchez-Palencia.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-026-05558-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Area Laws and Tensor Networks for Maximally Mixed Ground States","authors":"Itai Arad, Raz Firanko, Rahul Jain","doi":"10.1007/s00220-026-05554-z","DOIUrl":"10.1007/s00220-026-05554-z","url":null,"abstract":"<div><p>We show an area law in the mutual information for the maximally-mixed state <span>(Omega )</span> in the ground space of general Hamiltonians, which is independent of the underlying ground space degeneracy. Our result assumes the existence of a ‘good’ approximation to the ground state projector (a good AGSP), a crucial ingredient in previous area-law proofs. Such approximations have been explicitly derived for 1D gapped local Hamiltonians and 2D frustration-free locally-gapped Hamiltonians. As a corollary, we show that in 1D gapped local Hamiltonians, for any <span>(epsilon >0)</span> and any bipartition <span>(Lcup L^c)</span> of the system, </p><div><div><span>$$begin{aligned} textrm{I}^epsilon _{max } , ! ! left( L : L^c right) _{Omega } le {textrm{O}}left( log (|L|log (d))+log (1/epsilon )right) , end{aligned}$$</span></div></div><p>where |<i>L</i>| represents the number of sites in <i>L</i>, <i>d</i> is the dimension of a site and <span>( textrm{I}^epsilon _{max } , ! ! left( L : L^c right) _{Omega })</span> represents the <span>(epsilon )</span>-<i>smoothed maximum mutual information</i> with respect to the <span>(L:L^c)</span> partition in <span>(Omega )</span>. From this bound we then conclude <span>( textrm{I} , ! ! left( L : L^c right) _Omega le {textrm{O}}left( log (|L|log (d))right) )</span> – an area law for the mutual information in 1D systems with a logarithmic correction. In addition, we show that <span>(Omega )</span> can be approximated in trace norm up to <span>(epsilon )</span> with a state of Schmidt rank of at most <span>(textrm{poly}(|L|log (d)/epsilon ))</span>, leading to a good MPO approximation for <span>(Omega )</span> with polynomial bond dimension. Similar corollaries are derived for the mutual information of 2D frustration-free and locally-gapped local Hamiltonians.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-026-05554-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Paolo Lorenzoni, Sara Perletti, Karoline van Gemst
{"title":"Semi-Hamiltonian Properties of a Class of Non-diagonalisable Systems of Hydrodynamic Type","authors":"Paolo Lorenzoni, Sara Perletti, Karoline van Gemst","doi":"10.1007/s00220-025-05544-7","DOIUrl":"10.1007/s00220-025-05544-7","url":null,"abstract":"<div><p>We study the system of first order PDEs for pseudo-Riemannian metrics governing the Hamiltonian formalism for systems of hydrodynamic type. In the diagonal setting the integrability conditions ensure the compatibility of this system and, thanks to a classical theorem of Darboux, the existence of a family of solutions depending on functional parameters. In this paper we study the generalisation of this result to a class of non-diagonalisable systems of hydrodynamic type that naturally generalises Tsarev’s integrable diagonal systems.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Approximate Unitary k-Designs from Shallow, Low-Communication Circuits","authors":"Nicholas LaRacuente, Felix Leditzky","doi":"10.1007/s00220-025-05542-9","DOIUrl":"10.1007/s00220-025-05542-9","url":null,"abstract":"<div><p>Random unitaries are useful in quantum information and related fields, but hard to generate with limited resources. An approximate unitary <i>k</i>-design is an ensemble of unitaries with an underlying measure over which the average is close to a Haar random ensemble up to the first <i>k</i> moments. A particularly strong notion of approximation bounds the distance from Haar randomness in relative error. Such relative-error approximate designs are secure against queries by an adaptive adversary trying to distinguish it from a Haar ensemble. We construct relative-error approximate unitary <i>k</i>-design ensembles for which communication between subsystems is <i>O</i>(1) in the system size. These constructions use the alternating projection method to analyze overlapping Haar averages, giving a bound on the convergence speed to the full averaging with respect to the 2-norm. Using von Neumann subalgebra indices to replace system dimension, the 2-norm distance converts to relative error without introducing any additional dimension dependence. We use these constructions as the building blocks of a two-step protocol that achieves a relative-error design in <span>(O big ( (log m + log (1/epsilon ) + k log k ) k, text {polylog}(k) big ))</span> depth, where <i>m</i> is the number of qudits in the complete system and <span>(epsilon )</span> the approximation error. This sublinear depth construction answers a variant of [21, Harrow and Mehraban 2023, Section 1.5, Open Question 1] and [21, Harrow and Mehraban 2023, Section 1.5, Open Question 7]. Moreover, entanglement generated by the sublinear depth scheme follows area laws on spatial lattices up to corrections logarithmic in the full system size.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-025-05542-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Periodic Pitman Transforms and Jointly Invariant Measures","authors":"Ivan Corwin, Yu Gu, Evan Sorensen","doi":"10.1007/s00220-025-05541-w","DOIUrl":"10.1007/s00220-025-05541-w","url":null,"abstract":"<div><p>We construct explicit jointly invariant measures for the periodic KPZ equation (and therefore also the stochastic Burgers’ and stochastic heat equations) for general slope parameters and prove their uniqueness via a one force–one solution principle. The measures are given by polymer-like transforms of independent Brownian bridges. We describe several properties and limits of these measures, including an extension to a continuous process in the slope parameter that we term the periodic KPZ horizon. As an application of our construction, we prove a Gaussian process limit theorem with an explicit covariance function for the long-time height function fluctuations of the periodic KPZ equation when started from varying slopes. In connection with this, we conjecture a formula for the fluctuations of cumulants of the endpoint distribution for the periodic continuum directed random polymer. To prove joint invariance, we address the analogous problem for a semi-discrete system of SDEs related to the periodic O’Connell–Yor polymer model and then perform a scaling limit of the model and jointly invariant measures. For the semi-discrete system, we demonstrate a bijection that maps our systems of SDEs to another system with product invariant measure. Inverting the map on this product measure yields our invariant measures. This map relates to a periodic version of the discrete geometric Pitman transform that we introduce and probe. As a by-product of this, we show that the jointly invariant measures for a periodic version of the inverse-gamma polymer are the same as those for the O’Connell–Yor polymer.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Liouville Type Theorems for the Stationary Navier–Stokes Equations in (mathbb {R}^3)","authors":"Dongho Chae","doi":"10.1007/s00220-026-05555-y","DOIUrl":"10.1007/s00220-026-05555-y","url":null,"abstract":"<div><p>In this paper we prove Liouville type theorems for the stationary solution to the Navier–Stokes equations in <span>(mathbb {R}^3)</span>. Let (<i>u</i>, <i>p</i>) be a smooth stationary solution to the Navier–Stokes equations in <span>(mathbb {R}^3)</span>, and <span>(Q=frac{1}{2} |u|^2 +p)</span> is its head pressure, which vanishes near infinity. We assume <span>(int _{mathbb {R}^3} |nabla u|^2 dx<+infty ,)</span> and there exists <span>(alpha >0 )</span>, <span>(C>0)</span> and <span>(R>0)</span> such that <span>( |Q(x)| ge C Vert QVert _{L^infty }|x|^{-alpha })</span> for all <span>(|x|>R)</span>. Suppose, furthermore, there exists <span>(beta )</span> such that <i>either</i> <span>(|u(x)|=O( |x|^{-beta }))</span> with <span>(beta ge frac{alpha }{2})</span> <i>or</i> <span>(|nabla Q(x)|=O( |x|^{-beta }))</span> with <span>(beta ge 2alpha )</span> respectively as <span>(|x|rightarrow +infty )</span>. Then, we show that <i>u</i> is zero or a constant respectively on <span>(mathbb {R}^3)</span>.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00220-026-05555-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Benjamin Eichinger, Milivoje Lukić, Peter Yuditskii
{"title":"On Point Spectrum of Jacobi Matrices Generated by Iterations of Quadratic Polynomials","authors":"Benjamin Eichinger, Milivoje Lukić, Peter Yuditskii","doi":"10.1007/s00220-025-05549-2","DOIUrl":"10.1007/s00220-025-05549-2","url":null,"abstract":"<div><p>In general, point spectrum of an almost periodic Jacobi matrix can depend on the element of the hull. In this paper, we study the hull of the limit-periodic Jacobi matrix corresponding to the equilibrium measure of the Julia set of the polynomial <span>(z^2-lambda )</span> with large enough <span>(lambda )</span>; this is the leading model in inverse spectral theory of ergodic operators with zero measure spectrum. We prove that every element of the hull has empty point spectrum. To prove this, we introduce a matrix version of Ruelle operators.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Hypertoric 2-Categories (mathcal {O}) and Symplectic Duality","authors":"Benjamin Gammage, Justin Hilburn","doi":"10.1007/s00220-026-05552-1","DOIUrl":"10.1007/s00220-026-05552-1","url":null,"abstract":"<div><p>We define 2-categories of microlocal perverse (resp. coherent) sheaves of categories on the skeleton of a hypertoric variety and show that the generators of these 2-categories lift the projectives (resp. simples) in hypertoric category <span>({mathcal {O}}.)</span> We then establish equivalences of 2-categories categorifying the Koszul duality between Gale dual hypertoric categories <span>({mathcal {O}}.)</span> These constructions give a prototype for understanding symplectic duality via the fully extended 3d mirror symmetry conjecture.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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":"Line Operators in U(1|1) Chern–Simons Theory","authors":"Niklas Garner, Wenjun Niu","doi":"10.1007/s00220-025-05546-5","DOIUrl":"10.1007/s00220-025-05546-5","url":null,"abstract":"<div><p>We analyze the non-semisimple category of line operators in Chern–Simons gauge theories based off the Lie superalgebra <span>(mathfrak {gl}(1|1))</span>. Our proposal is that the category of line operators <span>(mathcal {C})</span> can be identified with the derived category of modules for a boundary vertex operator algebra <span>(mathcal {V})</span> realized as a certain infinite-order simple current extension of the affine current algebra <span>(V(mathfrak {gl}(1|1)))</span> by boundary monopole operators. By translating this simple current extension of <span>(V(mathfrak {gl}(1|1)))</span> to the unrolled, restricted quantum group <span>(overline{U}^E(mathfrak {gl}(1|1)))</span>, we show that our category of line operators admits a second description in terms of a quasi-quantum group <span>(mathcal {A})</span> realized by uprolling. We also compare our results across an expected physical duality with the cyclic orbifold of a free, <i>B</i>-twisted hypermultiplet and find a slight discrepancy at the level of braiding and associator. We end with a detailed analysis of coupling to background flat <span>(GL(1, {mathbb {C}}))</span> connections and the resulting category of non-genuine line operators.\u0000</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}
Eric D’Hoker, Benjamin Enriquez, Oliver Schlotterer, Federico Zerbini
{"title":"Relating Flat Connections and Polylogarithms on Higher Genus Riemann Surfaces","authors":"Eric D’Hoker, Benjamin Enriquez, Oliver Schlotterer, Federico Zerbini","doi":"10.1007/s00220-025-05540-x","DOIUrl":"10.1007/s00220-025-05540-x","url":null,"abstract":"<div><p>In this work, we relate two recent constructions that generalize classical (genus-zero) polylogarithms to higher-genus Riemann surfaces. A flat connection valued in a freely generated Lie algebra on a punctured Riemann surface of arbitrary genus produces an infinite family of homotopy-invariant iterated integrals associated to all possible words in the alphabet of the Lie algebra generators. Each iterated integral associated to a word is a higher-genus polylogarithm. Different flat connections taking values in the same Lie algebra on a given Riemann surface may be related to one another by the composition of a gauge transformation and an automorphism of the Lie algebra, thus producing closely related families of polylogarithms. In this paper we provide two methods, which are inverses of one another, to explicitly relate in this way the meromorphic multiple-valued connection introduced by Enriquez in e-Print 1112.0864 and the non-meromorphic single-valued and modular-invariant connection introduced by D’Hoker, Hidding and Schlotterer, in e-Print 2306.08644.</p></div>","PeriodicalId":522,"journal":{"name":"Communications in Mathematical Physics","volume":"407 3","pages":""},"PeriodicalIF":2.6,"publicationDate":"2026-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147337183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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}