Real-time Dynamics in U(1) Lattice Gauge Theories with Tensor Networks

Tensor network algorithms provide a suitable route for tackling real-time dependent problems in lattice gauge theories, enabling the investigation of out-of-equilibrium dynamics. We analyze a U(1) lattice gauge theory in (1+1) dimensions in the presence of dynamical matter for different mass and electric field couplings, a theory akin to quantum-electrodynamics in one-dimension, which displays string-breaking: the confining string between charges can spontaneously break during quench experiments, giving rise to charge-anticharge pairs according to the Schwinger mechanism. We study the real-time spreading of excitations in the system by means of electric field and particle fluctuations: we determine a dynamical state diagram for string breaking and quantitatively evaluate the time-scales for mass production. We also show that the time evolution of the quantum correlations can be detected via bipartite von Neumann entropies, thus demonstrating that the Schwinger mechanism is tightly linked to entanglement spreading. To present the variety of possible applications of this simulation platform, we show how one could follow the real-time scattering processes between mesons and the creation of entanglement during scattering processes. Finally, we test the quality of quantum simulations of these dynamics, quantifying the role of possible imperfections in cold atoms, trapped ions, and superconducting circuit systems. Our results demonstrate how entanglement properties can be used to deepen our understanding of basic phenomena in the real-time dynamics of gauge theories such as string breaking and collisions.Comment: 15 pages, 25 figures. Published versio

Tensor networks for Lattice Gauge Theories and Atomic Quantum Simulation

We show that gauge invariant quantum link models, Abelian and non-Abelian, can be exactly described in terms of tensor networks states. Quantum link models represent an ideal bridge between high-energy to cold atom physics, as they can be used in cold-atoms in optical lattices to study lattice gauge theories. In this framework, we characterize the phase diagram of a (1+1)-d quantum link version of the Schwinger model in an external classical background electric field: the quantum phase transition from a charge and parity ordered phase with non-zero electric flux to a disordered one with a net zero electric flux configuration is described by the Ising universality class.Comment: 9 pages, 9 figures. Published versio

Sampling motif-constrained ensembles of networks

The statistical significance of network properties is conditioned on null models which satisfy spec- ified properties but that are otherwise random. Exponential random graph models are a principled theoretical framework to generate such constrained ensembles, but which often fail in practice, either due to model inconsistency, or due to the impossibility to sample networks from them. These problems affect the important case of networks with prescribed clustering coefficient or number of small connected subgraphs (motifs). In this paper we use the Wang-Landau method to obtain a multicanonical sampling that overcomes both these problems. We sample, in polynomial time, net- works with arbitrary degree sequences from ensembles with imposed motifs counts. Applying this method to social networks, we investigate the relation between transitivity and homophily, and we quantify the correlation between different types of motifs, finding that single motifs can explain up to 60% of the variation of motif profiles.Comment: Updated version, as published in the journal. 7 pages, 5 figures, one Supplemental Materia

Two-dimensional Lattice Gauge Theories with Superconducting Quantum Circuits

A quantum simulator of U(1) lattice gauge theories can be implemented with superconducting circuits. This allows the investigation of confined and deconfined phases in quantum link models, and of valence bond solid and spin liquid phases in quantum dimer models. Fractionalized confining strings and the real-time dynamics of quantum phase transitions are accessible as well. Here we show how state-of-the-art superconducting technology allows us to simulate these phenomena in relatively small circuit lattices. By exploiting the strong non-linear couplings between quantized excitations emerging when superconducting qubits are coupled, we show how to engineer gauge invariant Hamiltonians, including ring-exchange and four-body Ising interactions. We demonstrate that, despite decoherence and disorder effects, minimal circuit instances allow us to investigate properties such as the dynamics of electric flux strings, signaling confinement in gauge invariant field theories. The experimental realization of these models in larger superconducting circuits could address open questions beyond current computational capability.Comment: Published versio

KAJIAN YURIDIS PERKARA KEMATIAN AKLI FAIRUZ PADA PERTANDINGAN SEPAKBOLA PERSIRAJA BANDA ACEH MELAWAN PSAP SIGLI

Abstrak Sepakbola merupakan olahraga paling populer di Indonesia. Sepakbola adalah salah satu olahraga yang tidak bisa dihindari terjadinya kontak fisik. Hal ini menyebabkan seringnya terjadi tindak kekerasan di sebuah pertandingan sepakbola. Kasus kekerasan terhadap pemain di persepakbolaan Indonesia kerap terjadi. Cidera ringan hingga meninggal dunia merupakan akibat dari tindak kekerasan terhadap lawan yang sudah pernah terjadi di Indonesia. Kasus meninggalnya Akli Fairuz pada pertandingan Persiraja melawan PSAP menjadi contoh akibat dari tindak kekerasan yang terjadi di persepakbolaan Indonesia. Kekerasan yang terjadi dilapangan sepakbola kerap tak tersentuh oleh hukum nasional karena dianggap masih menjadi wewenang PSSI yang didasarkan pada statutanya. Batasan yang kurang jelas sering sulit untuk mengklasifikasikan tindakan kekerasan dalam sepakbola sebagai pelanggaran disiplin ataukah tindak pidana. Kekaburan batasan tersebut juga menjadi penyebab dipertanyakannya tindakan yang dilakukan oleh Agus Rohman yang menyebabkan Akli Fairuz meninggal dunia. Statuta PSSI pada pasal 70 menyatakan bahwa PSSI memiliki yurisdiksi hukum sendiri terkait penyelesaian perkara yang ada dalam persepakbolaan di Indonesia, karena itu statuta PSSI melarang setiap perkara dalam sepakbola diajukan ke pengadilan negeri.Hal ini menjadi rancu ketika kedudukan PSSI sebagai badan hukum menolak semua perkara sepakbola diselesaikan di pengadilan negeri, sedangkan dalam pasal 2 KUHP semua kejahatan atau tindak pidana yang terjadi di Indonesia merupakan wewenang hukum pidana nasional.Tujuan penelitian ini adalah untuk menganalisis batasan tindak kekerasan dalam sepakbola masih termasuk pelanggaran disiplin ataukah tindak pidana. Batasan yang jelas akan mampu mengklasifikasikan perbuatan yang dilakukan oleh Agus Rohman serta akibat yang ditimbulkan, masuk ke dalam pelanggaran disiplin atau tindak pidana. Metode penelitian yang digunakan adalah normatif. Kasus yang dianalisis disinergikan dengan dasar peraturan sepakbola serta undang-undang terkait yang mengatur. Buku-buku literatur yang digunakan juga dijadikan pedoman untuk mencari teori serta norma yang dipakai.Hasil dari penelitian ini adalah menunjukkan tindakan yang dilakukan oleh Agus Rohman tergolong suatu perbuatan pidana karena melanggar unsur obyektif dan subyektif dari parameter kekerasan di legitimates of sport. Tindakan tersebut tergolong sebagai Criminal Violance. Tindakan Agus Rohman juga memenuhi unsur-unsur dalam delik penganiayaan. Penyelesaian perkara secara hukum pidana tersebut menghapus yurisdiksi PSSI yang absolut. Ketentuan pasal 70 statuta PSSI yang bertentangan dengan KUHP harus dihapus atau diganti dengan yang lebih sesuai dengan hukum pidana nasional. Kata Kunci : Kematian Akli Fairuz, Agus Rohman, Kekerasan dalam sepakbola, Statuta PSSI Abstract Football is the most popular sport in Indonesia. Football is one sport that can not be avoided physical contact. This causes frequent violence at a football match. Cases of violence against Indonesian football players often occur. Minor injuries to death was the result of acts of violence against an opponent that has never happened in Indonesia. Akli Fairuz death case in the match against PSAP Persiraja be an example as a result of the violence that occurred in Indonesian football. The violence that happens on a football pitch are often untouched by national law because it is still a PSSI authority based on statute. Less obvious limitation is often difficult to classify acts of violence in football as a disciplinary offense or a criminal act. The blurring of boundaries may also lead to questioning the actions carried out by Agus Rohman which causes Akli Fairuz died. PSSI to article 70 of the Statute states that the PSSI has its own legal jurisdiction related to the settlement that exist in football in Indonesia, because the PSSI statutes prohibit any football matters in the country are brought to justice. It becomes confusing when standing PSSI as a legal entity to reject all football matters resolved in the district court, whereas in Article 2 of the Criminal Code all crimes or offenses which occurred in Indonesia is the authority of national criminal law. The purpose of this study was to analyze the limits of violence in football is still a violation of discipline or criminal acts. Clear boundaries will be able to classify the actions undertaken by Agus Rohman and consequences, entered into a disciplinary offense or a crime. The method used is normative. Cases analyzed synergized with the basic rules of football as well as the pertinent laws governing. Literature books used are also used as guidelines to seek theories and norms used. The results of this study is to show the actions performed by Agus Rohman classified as a criminal offense for violating the element of objective and subjective parameters of legitimates violence in sport. Such actions are classified as Criminal Violance. Agus Rohman actions also fulfill the elements in the offense of persecution. The settlement under the criminal law of the jurisdiction PSSI remove the absolute. The provisions of Article 70 of the statutes of PSSI contrary to the Criminal Code should be removed or replaced with a more suitable to the national criminal law. Keywords: Death Akli Fairuz, Agus Rohman, Violence in football, the Statute of the PSS

SO(3) "Nuclear Physics" with ultracold Gases

An ab initio calculation of nuclear physics from Quantum Chromodynamics (QCD), the fundamental SU(3) gauge theory of the strong interaction, remains an outstanding challenge. Here, we discuss the emergence of key elements of nuclear physics using an SO(3) lattice gauge theory as a toy model for QCD. We show that this model is accessible to state-of-the-art quantum simulation experiments with ultracold atoms in an optical lattice. First, we demonstrate that our model shares characteristic many-body features with QCD, such as the spontaneous breakdown of chiral symmetry, its restoration at finite baryon density, as well as the existence of few-body bound states. Then we show that in the one-dimensional case, the dynamics in the gauge invariant sector can be encoded as a spin S=3/2 Heisenberg model, i.e., as quantum magnetism, which has a natural realization with bosonic mixtures in optical lattices, and thus sheds light on the connection between non-Abelian gauge theories and quantum magnetism.Comment: 34 pages, 9 figure