Continuum approach to real time dynamics of 1+1D gauge field theory: out of horizon correlations of the Schwinger model

We develop a truncated Hamiltonian method to study nonequilibrium real time dynamics in the Schwinger model - the quantum electrodynamics in D=1+1. This is a purely continuum method that captures reliably the invariance under local and global gauge transformations and does not require a discretisation of space-time. We use it to study a phenomenon that is expected not to be tractable using lattice methods: we show that the 1+1D quantum electrodynamics admits the dynamical horizon violation effect which was recently discovered in the case of the sine-Gordon model. Following a quench of the model, oscillatory long-range correlations develop, manifestly violating the horizon bound. We find that the oscillation frequencies of the out-of-horizon correlations correspond to twice the masses of the mesons of the model suggesting that the effect is mediated through correlated meson pairs. We also report on the cluster violation in the massive version of the model, previously known in the massless Schwinger model. The results presented here reveal a novel nonequilibrium phenomenon in 1+1D quantum electrodynamics and make a first step towards establishing that the horizon violation effect is present in gauge field theory.Comment: 9+7 pages, 7 figures. V2: Additional results adde

Out-of-horizon correlations following a quench in a relativistic quantum field theory

One of the manifestations of relativistic invariance in non-equilibrium quantum field theory is the "horizon effect" a.k.a. light-cone spreading of correlations: starting from an initially short-range correlated state, measurements of two observers at distant space-time points are expected to remain independent until their past light-cones overlap. Surprisingly, we find that in the presence of topological excitations correlations can develop outside of horizon and indeed even between infinitely distant points. We demonstrate this effect for a wide class of global quantum quenches to the sine-Gordon model. We point out that besides the maximum velocity bound implied by relativistic invariance, clustering of initial correlations is required to establish the "horizon effect". We show that quenches in the sine-Gordon model have an interesting property: despite the fact that the initial states have exponentially decaying correlations and cluster in terms of the bosonic fields, they violate the clustering condition for the soliton fields, which is argued to be related to the non-trivial field topology. The nonlinear dynamics governed by the solitons makes the clustering violation manifest also in correlations of the local bosonic fields after the quench.Comment: 19+14 pages, 8 figures, pdflatex, v2: presentation substantially improved, new details concerning the effect are added, v3: reformatted version, references added, results and essential conclusions unchanged, with title update

Correlation Functions of the Quantum Sine-Gordon Model in and out of Equilibrium

Complete information on the equilibrium behaviour and dynamics of a quantum field theory (QFT) is provided by multipoint correlation functions. However, their theoretical calculation is a challenging problem, even for exactly solvable models. This has recently become an experimentally relevant problem, due to progress in cold-atom experiments simulating QFT models and directly measuring higher order correlations. Here we compute correlation functions of the quantum sine-Gordon model, a prototype integrable model of central interest from both theoretical and experimental points of view. Building upon the so-called Truncated Conformal Space Approach, we numerically construct higher order correlations in a system of finite size in various physical states of experimental relevance, both in and out of equilibrium. We measure deviations from Gaussianity due to the presence of interaction and analyse their dependence on temperature, explaining the experimentally observed crossover between Gaussian and non-Gaussian regimes. We find that correlations of excited states are markedly different from the thermal case, which can be explained by the integrability of the system. We also study dynamics after a quench, observing the effects of the interaction on the time evolution of correlation functions, their spatial dependence, and their non-Gaussianity as measured by the kurtosis.Comment: Animation of quench dynamics in ancillary material: https://arxiv.org/src/1802.08696/anc/animation.mp4 Version 2: Improved presentation; Version 3: Final version after the peer review proces

LiDAR analize okolice Jame kod Rašpora: upotpunjavanje speleološke priče

2020. godine u okviru projekta „Kaštelir“ provedeno je detaljno LiDAR snimanje površine 9,15 km2 oko lokaliteta gradine Rašpor u Istri radi arheoloških istraživanja. Obzirom da se na tom području prostiru i svi istraženi kanali Jame kod Rašpora ukupne duljine preko 7200 m, ovi podaci analizirani su u svrhu pronalaska potencijalnih speleoloških objekata koji bi mogli omogućiti vezu s dubokim rašporskim podzemljem. Na ovom području od prije su poznate 34 špilje, jame, izvora, ponora i puhalica, a LiDAR analizama pronađeno je 49 potencijalnih ulaza u speleološke objekte. Analize su pokazale preklapanje s prije poznatim podacima u 22 slučaja. U konačnici, na već detaljno rekognosciranom terenu pronađeno je 5 do sada nepoznatih ulaza u speleološke objekte te se obrada LiDAR podataka još jednom pokazala kao moćan alat u provedbi sustavnih speleoloških istraživanja nekog područja