SciPost physics core最新文献

{"title":"Local operator entanglement in spin chains","authors":"Eric Mascot, Masahiro Nozaki, Masaki Tezuka","doi":"10.21468/scipostphyscore.6.4.070","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.4.070","url":null,"abstract":"Understanding how and whether local perturbations can affect the entire quantum system is a fundamental step in understanding non-equilibrium phenomena such as thermalization. This knowledge of non-equilibrium phenomena is applicable for quantum computation, as many quantum computers employ non-equilibrium processes for computations. In this paper, we investigate the evolution of bi- and tripartite operator mutual information of the time-evolution operator and the Pauli spin operators in the one-dimensional Ising model with magnetic field and the disordered Heisenberg model to study the properties of quantum circuits. In the Ising model, the early-time evolution qualitatively follows an effective light cone picture, and the late-time value is well described by Page’s value for a random pure state. In the Heisenberg model with strong disorder, we find that many-body localization prevents the information from propagating and being delocalized. We also find an effective Ising Hamiltonian that describes the time evolution of bi- and tripartite operator mutual information for the Heisenberg model in the large disorder regime.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569274","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Matrix product operator representations for the local conserved quantities of the Heisenberg chain","authors":"Kyoichi Yamada, Kouhei Fukai","doi":"10.21468/scipostphyscore.6.4.069","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.4.069","url":null,"abstract":"We present the explicit expressions for the matrix product operator (MPO) representation for the local conserved quantities of the Heisenberg chain. The bond dimension of the MPO grows linearly with the locality of the charges. The MPO has more simple form than the local charges themselves, and their Catalan tree patterns naturally emerge from the matrix products. The MPO representation of local conserved quantities is generalized to the integrable SU(N) invariant spin chain.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135779244","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quasi-characters in $widehat{su(2)}$ current algebra at fractional levels","authors":"Sachin Grover","doi":"10.21468/scipostphyscore.6.4.068","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.4.068","url":null,"abstract":"We study the even characters of widehat{su(2)} <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mover><mml:mrow><mml:mi>s</mml:mi><mml:mi>u</mml:mi><mml:mrow><mml:mo stretchy=\"true\" form=\"prefix\">(</mml:mo><mml:mn>2</mml:mn><mml:mo stretchy=\"true\" form=\"postfix\">)</mml:mo></mml:mrow></mml:mrow><mml:mo accent=\"true\">^</mml:mo></mml:mover></mml:math> conformal field theories (CFTs) at admissible fractional levels obtained from the difference of the highest weight characters in the unflavoured limit. We show that admissible even character vectors arise only in three special classes of admissible fractional levels which include the threshold levels, the positive half-odd integer levels, and the isolated level at - 5/4 <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mn>5</mml:mn><mml:mi>/</mml:mi><mml:mn>4</mml:mn></mml:mrow></mml:math> . Among them, we show that the even characters of the half-odd integer levels map to the difference of characters of widehat{su(2)}_{4N+4} <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:msub><mml:mover><mml:mrow><mml:mi>s</mml:mi><mml:mi>u</mml:mi><mml:mrow><mml:mo stretchy=\"true\" form=\"prefix\">(</mml:mo><mml:mn>2</mml:mn><mml:mo stretchy=\"true\" form=\"postfix\">)</mml:mo></mml:mrow></mml:mrow><mml:mo accent=\"true\">^</mml:mo></mml:mover><mml:mrow><mml:mn>4</mml:mn><mml:mi>N</mml:mi><mml:mo>+</mml:mo><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:math> , with Ninmathbb{Z}_{&amp;gt;0} <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mi>N</mml:mi><mml:mo>∈</mml:mo><mml:msub><mml:mi>ℤ</mml:mi><mml:mn>^0</mml:mn></mml:msub></mml:mrow></mml:math> , although we prove that they do not correspond to rational CFTs. The isolated level characters maps to characters of two subsectors with widehat{so(5)}_1 <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:msub><mml:mover><mml:mrow><mml:mi>s</mml:mi><mml:mi>o</mml:mi><mml:mrow><mml:mo stretchy=\"true\" form=\"prefix\">(</mml:mo><mml:mn>5</mml:mn><mml:mo stretchy=\"true\" form=\"postfix\">)</mml:mo></mml:mrow></mml:mrow><mml:mo accent=\"true\">^</mml:mo></mml:mover><mml:mn>1</mml:mn></mml:msub></mml:math> and widehat{su(2)}_1 <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:msub><mml:mover><mml:mrow><mml:mi>s</mml:mi><mml:mi>u</mml:mi><mml:mrow><mml:mo stretchy=\"true\" form=\"prefix\">(</mml:mo><mml:mn>2</mml:mn><mml:mo stretchy=\"true\" form=\"postfix\">)</mml:mo></mml:mrow></mml:mrow><mml:mo accent=\"true\">^</mml:mo></mml:mover><mml:mn>1</mml:mn></mml:msub></mml:math> current algebras. Furthermore, for the widehat{su(2)}_1 <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:msub><mml:mover><mml:mrow><mml:mi>s</mml:mi><mml:mi>u</mml:mi><mml:mrow><mml:mo stretchy=\"true\" form=\"prefix\">(</mml:mo><mml:mn>2</mml:mn><mml:mo stretchy=\"true\" form=\"postfix\">)</mml:mo></mml:mrow></mml:mrow","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135888584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal mass variables for semivisible jets","authors":"Kevin Pedro, Prasanth Shyamsundar","doi":"10.21468/scipostphyscore.6.4.067","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.4.067","url":null,"abstract":"Strongly coupled hidden sector theories predict collider production of invisible, composite dark matter candidates mixed with standard model hadrons in the form of semivisible jets. Classical mass reconstruction techniques may not be optimal for these unusual topologies, in which the missing transverse momentum comes from massive particles and has a nontrivial relationship to the visible jet momentum. We apply the artificial event variable network, a semisupervised, interpretable machine learning technique that uses an information bottleneck, to derive superior mass reconstruction functions for several cases of resonant semivisible jet production. We demonstrate that the technique can extrapolate to unknown signal model parameter values. We further demonstrate the viability of conducting an actual search for new physics using this method, by applying the learned functions to standard model background events from quantum chromodynamics.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136032762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological holography: Towards a unification of Landau and beyond-Landau physics","authors":"Heidar Moradi, Seyed Faroogh Moosavian, Apoorv Tiwari","doi":"10.21468/scipostphyscore.6.4.066","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.4.066","url":null,"abstract":"We outline a holographic framework that attempts to unify Landau and beyond-Landau paradigms of quantum phases and phase transitions. Leveraging a modern understanding of symmetries as topological defects/operators, the framework uses a topological order to organize the space of quantum systems with a global symmetry in one lower dimension. The global symmetry naturally serves as an input for the topological order. In particular, we holographically construct a String Operator Algebra (SOA) which is the building block of symmetric quantum systems with a given symmetry G in one lower dimension. This exposes a vast web of dualities which act on the space of G-symmetric quantum systems. The SOA facilitates the classification of gapped phases as well as their corresponding order parameters and fundamental excitations, while dualities help to navigate and predict various corners of phase diagrams and analytically compute universality classes of phase transitions. A novelty of the approach is that it treats conventional Landau and unconventional topological phase transitions on an equal footing, thereby providing a holographic unification of these seemingly-disparate domains of understanding. We uncover a new feature of gapped phases and their multi-critical points, which we dub fusion structure, that encodes information about which phases and transitions can be dual to each other. Furthermore, we discover that self-dual systems typically posses emergent non-invertible, i.e., beyond group-like symmetries. We apply these ideas to 1+1d <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mn>1</mml:mn><mml:mo>+</mml:mo><mml:mn>1</mml:mn><mml:mi>d</mml:mi></mml:mrow></mml:math> quantum spin chains with finite Abelian group symmetry, using topologically-ordered systems in 2+1d <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mn>2</mml:mn><mml:mo>+</mml:mo><mml:mn>1</mml:mn><mml:mi>d</mml:mi></mml:mrow></mml:math> . We predict the phase diagrams of various concrete spin models, and analytically compute the full conformal spectra of non-trivial quantum phase transitions, which we then verify numerically.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"1140 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136114507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optically detected magnetic resonance with an open source platform","authors":"Hossein Babashah, Hoda Shirzad, Elena Losero, Valentin Goblot, Christophe Galland, Mayeul Chipaux","doi":"10.21468/scipostphyscore.6.4.065","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.4.065","url":null,"abstract":"Localized electronic spins in solid-state environments form versatile and robust platforms for quantum sensing, metrology and quantum information processing. With optically detected magnetic resonance (ODMR), it is possible to prepare and readout highly coherent spin systems, up to room temperature, with orders of magnitude enhanced sensitivities and spatial resolutions compared to induction-based techniques, allowing for single spin manipulations. While ODMR was first observed in organic molecules, many other systems have since then been identified. Among them is the nitrogen-vacancy (NV) center in diamond, which is used both as a nanoscale quantum sensor for external fields and as a spin qubit. Other systems permitting ODMR are rare earth ions used as quantum memories and many other color centers trapped in bulk or 2-dimensional host materials. In order to allow the broadest possible community of researchers and engineers to investigate and develop novel ODMR-based materials and applications, we review here the setting up of ODMR experiments using commercially available hardware. We also present in detail the dedicated collaborative open-source interface named Qudi and describe the features we added to speed-up data acquisition, relax instrument requirements and extend its applicability to ensemble measurements. Covering both hardware and software development, this article aims to overview the setting of ODMR experiments and provide an efficient, portable and collaborative interface to implement innovative experiments to optimize the development time of ODMR experiments for scientists of any backgrounds.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"65 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135045875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapidity distribution within the defocusing non-linear Schrödinger equation model","authors":"Yasser Bezzaz, Léa Dubois, Isabelle Bouchoule","doi":"10.21468/scipostphyscore.6.3.064","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.3.064","url":null,"abstract":"We consider the classical field integrable system whose evolution equation is the nonlinear Schrödinger equation with defocusing non-linearities, which is the classical limit of the quantum Lieb-Liniger model. We propose a simple derivation of the relation between two sets of conserved quantities: on the one hand the trace of the monodromy matrix, parameterized by the spectral parameter and introduced in the inverse-scattering framework, and on the other hand the rapidity distribution, a concept imported from the Lieb-Liniger model. To do so we use the definition of the rapidity distribution as the asymptotic momentum distribution after a very large expansion. We propose two different ways to derive the result, each one using a thought experiment that implements an expansion.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134903717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Entanglement classification via operator size","authors":"Qi-Feng Wu","doi":"10.21468/scipostphyscore.6.3.063","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.3.063","url":null,"abstract":"In this work, multipartite entanglement is classified by polynomials. I show that the operator size is closely related to the entanglement structure. Given a generic quantum state, I define a series of subspaces generated by operators of different sizes acting on it. The information about the entanglement is encoded into these subspaces. With the dimension of these subspaces as coefficients, I define a polynomial which I call the entanglement polynomial. The entanglement polynomial induces a homomorphism from quantum states to polynomials. It implies that we can characterize and find the building blocks of entanglement by polynomial factorization. Two states share the same entanglement polynomial if they are equivalent under the stochastic local operations and classical communication. To calculate the entanglement polynomial practically, I construct a series of states, called renormalized states, whose ranks are related to the coefficients of the entanglement polynomial.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135397258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relating non-Hermitian and Hermitian quantum systems at criticality","authors":"Chang-Tse Hsieh, Po-Yao Chang","doi":"10.21468/scipostphyscore.6.3.062","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.3.062","url":null,"abstract":"We demonstrate three types of transformations that establish connections between Hermitian and non-Hermitian quantum systems at criticality, which can be described by conformal field theories (CFTs). For the transformation preserving both the energy and the entanglement spectra, the corresponding central charges obtained from the logarithmic scaling of the entanglement entropy are identical for both Hermitian and non-Hermitian systems. The second transformation, while preserving the energy spectrum, does not perserve the entanglement spectrum. This leads to different entanglement entropy scalings and results in different central charges for the two types of systems. We demonstrate this transformation using the dilation method applied to the free fermion case. Through this method, we show that a non-Hermitian system with central charge c = -4 <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mi>c</mml:mi><mml:mo>=</mml:mo><mml:mo>−</mml:mo><mml:mn>4</mml:mn></mml:mrow></mml:math> can be mapped to a Hermitian system with central charge c = 2 <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mi>c</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math> . Lastly, we investigate the Galois conjugation in the Fibonacci model with the parameter phi to - 1/phi <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" display=\"inline\"><mml:mrow><mml:mi>ϕ</mml:mi><mml:mo>→</mml:mo><mml:mo>−</mml:mo><mml:mn>1</mml:mn><mml:mi>/</mml:mi><mml:mi>ϕ</mml:mi></mml:mrow></mml:math> , in which the transformation does not preserve both energy and entanglement spectra. We demonstrate the Fibonacci model and its Galois conjugation relate the tricritical Ising model/3-state Potts model and the Lee-Yang model with negative central charges from the scaling property of the entanglement entropy.","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135827797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction: Composite-boson formalism applied to strongly bound fermion pairs in a one-dimensional trap","authors":"Martín D. Jiménez, Eloisa Cuestas, Ana P. Majtey, Cecilia Cormick","doi":"10.21468/scipostphyscore.6.1.012-update-1","DOIUrl":"https://doi.org/10.21468/scipostphyscore.6.1.012-update-1","url":null,"abstract":"","PeriodicalId":471523,"journal":{"name":"SciPost physics core","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135488425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}