| 🔗 Next up |
| 2026 seminars |
| Real-time dynamics is central to high-energy physics, underlying processes such as particle scattering and the extraction of parton distribution functions (PDFs). However, nonperturbative real-time simulation remains challenging for classical methods due to signp roblems and rapidly growing entanglement, making quantum computing a promising alternative.
In this talk, I will present our recent progress on quantum simulations of particle scattering in (1+1)D lattice field theories. I will first discuss meson scattering in Z2 lattice gauge theory, focusing on the construction of stable particle creation operators and efficient quantum circuits. Using tensor network simulations, we observe both elastic and inelastic scattering, including particle production, entanglement growth, and the formation and breaking of extended flux strings. I will then present a hardware implementation of fermion scattering in the Thirring model on IBM Quantum devices with 40 and 80 qubits, where tensor-network-based circuit optimization and error mitigation enable results that closely match ideal simulations. Finally, I will briefly discuss ongoing directions, including resonance states in scattering and PDFs of the scalar meson in the Schwinger model. |
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Tuesday, May 26, 2026 11.00 (Rome) Euler Lecture Room (Leonardo Building, ICTP) |
Yahui Chai |
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| Quantum Simulation of Real-Time Scattering Dynamics in High-Energy Physics |
| The classical simulation of quantum field theories is a challenging problem. We will present a new method for the study of 1+1D quantum field theory models, built upon Hamiltonian Truncation and Tensor Network techniques, which is suitable for the study of low-energy eigenstates and out-of-equilibrium dynamics. Applications of the new method to the sine-Gordon and massive Schwinger model demonstrate that, despite its relatively high computational cost compared to typical Tensor Network applications, it dramatically improves precision compared to Exact Diagonalisation-based Hamiltonian Truncation, allowing the study of non-perturbative regimes of the models’ phase diagram and of far from equilibrium dynamics after a quantum quench. | ||
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Tuesday, May 19, 2026 11.00 (Rome) Room 128 (Via Bonomea 265, First Floor) |
Spyros Sotiriadis |
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| Hamiltonian Truncation Tensor Networks: a new numerical method for the simulation of 1+1D quantum field theory |
| Many statistical models of interacting spins can be reformulated as loop models through high-temperature expansions. At criticality, these models are described by a Conformal Field Theory (CFT). While the spectrum of critical exponents has been known since the late 1980s, the determination of correlation functions in loop models has seen little progress until the recent introduction of conformal bootstrap techniques.
In this talk, I will present our recent derivation of the three-point |
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Tuesday, May 12, 2026 11.00 (Rome) Sissa, Room 138 |
Paul Roux |
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| Correlation functions in critical loop models |
| I will discuss some work in progress describing scattering dilaton-graviton waves off of thin branes in a three dimensional space-time. The gravity problem has some novel aspects I have not seen in the general relativity literature before and is reminiscent of the optics problem of scattering light off of a rough, translucent window. The motivation for our study was that the process has a dual holographic realization as scattering in a family of strongly interacting (non-conformal) 1+1 dimensional quantum field theories. We are struggling with one or two remaining puzzles before releasing the work on the arXiv, and I hope the audience may help us to resolve them. |
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Tuesday, May 5, 2026 11.00 (Rome) Sissa, Room 138 |
Christopher Herzog |
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| Scattering Off Chamblin-Reall Branes |
| The quantum O(n) model has long served as a valuable framework for studying both equilibrium and dynamical properties of quantum many-body systems. In this talk, we investigate its non-equilibrium dynamics following a quantum quench in the large-n limit. While the model is known to be tractable in this regime, we show that it is in fact integrable – with integrals of motions stemming from that of the classical Neumann model – thus enabling a complete analytical solution of its dynamics. This integrability reveals a synchronization mechanism that gives rise to persistent oscillations, interpretable as Higgs modes localized at the edge of the spectral band. We further demonstrate that the long-time behavior is governed by a Generalized Gibbs Ensemble (GGE), in contrast to previous expectations, and we obtain exact critical exponents differing from those commonly reported. Remarkably, integrability persists even in the presence of long-range couplings, allowing us to explore the crossover between mean-field and genuinely many-body regimes in terms of parametric Floquet resonances of the microscopic degrees of freedom. | ||
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Tuesday 21 April, 2026 11.00 (Rome) Sissa, Room 128 |
Guido Giachetti |
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| Integrable Dynamics and Thermalization in the Quantum O(n) Model at Large n |
| In this talk I will discuss the task of charting phase diagrams of perturbed conformal field theories (CFT). I will explain how massive perturbations can be labelled by conformal boundary conditions in the UV CFT. I will then describe how the phase diagrams of perturbed 2D CFTs can be found numerically via truncated Hamiltonians and the attempts to describe them analytically using variational ansatze based on conformal boundary conditions. Various challenges for the analytic description will be discussed. | ||
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Tuesday, April 14, 2026 11.00 (Rome) Room 128 (Via Bonomea 265, First Floor) |
Anatoly Konechny |
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| Phase diagrams of perturbed CFTs and conformal boundary conditions |
| The Ryu-Takayanagi holographic entanglement entropy formula is a cornerstone of our modern understanding of holography and quantum gravity. It predicts that static holographic states have many peculiar properties, expressed as inequalities obeyed by entanglement entropies. These inequalities remain deeply mysterious, both on conceptual and technical levels. Can we decode what they’re telling us about the entanglement structure of semiclassical states in quantum gravity? For that, we need to know if the inequalities are obeyed in time-dependent states, in other words by the covarianet Hubeny-Rangamani-Takayanagi formula. This is itself a fascinating problem in general relativity. We will review the state of the art on these questions, including the attempts to resolve them and the evidence that has been gathered so far. | ||
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Tuesday, March 10, 2026 11.00 (Rome) Room 138, First Floor, SISSA (via Bonomea) |
Matthew Headrick |
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| Mysterious properties of holographic entanglement |
| I will present recent results on noisy quantum chaotic dynamics, with a particular focus on wave-function anticoncentration—characterized, for instance, through bitstrings output distributions—and on information-protected phases that persist at finite circuit depth. | ||
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Tuesday, March 3, 2026 11.00 (Rome) Room 138 (Via Bonomea 265, First Floor) |
Jacopo de Nardis |
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| Anticoncentration of Wave Functions and Information-Protected Phases in Noisy Quantum Chaotic Systems |
| Local measurements can radically reshape patterns of many-body entanglement, especially in long-range entangled quantum-critical states. Yet, analytical results addressing the effects of measurements on many-body states remain scarce, and measurements are often approximated as forcing specific measurement outcomes. In this talk, I will discuss measurement-induced entanglement (MIE) in Tomonaga-Luttinger liquids, a broad family of 1+1d quantum critical states described at low energies by compact free boson conformal field theories (CFT). Measuring the local charge operator, I will show that the MIE is entirely universal, conformally invariant, and can be computed exactly using a replica trick. I will also discuss recent work on the full distribution of MIE, and comment on the general description of measurements in quantum field theories. | ||
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Wednesday, February 25, 2026 14.00 (Rome) Room 138 (Via Bonomea 265, First Floor) |
Romain Vasseur |
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| Measurement-induced entanglement in gapless quantum matter |
| The observation of surprisingly long-lasting oscillations in the dynamics of a highly excited states of Rydberg atoms has attracted a lot of interest, as they defy the expectation that interacting systems should thermalize very quickly. The observed phenomena are reminiscent of “scars” that occur in quantum chaotic billiards, where single particle eigenfunctions retain traces of periodic classical orbits. Meanwhile a large number of models has been found that host one or several towers of special (non-thermal) eigenstates whose exactly equidistant eigen-energies ensure periodic, non-thermalizing motion.
In this talk I will discuss the unifying principles governing the solvable models and show how the (non-solvable) Rydberg chain fits into this framework. I further discuss a potential connection of the special ‘scar’ states of Rydberg chains with single particle scars in quantum billiards. I will show that there is a natural classical limit of the Rydberg system that features unexpectedly stable periodic orbits, that act as islands of parametrically suppressed chaos in the semiclassical limit. This opens a new perspective on the limits of quantum chaoticity in the many body-context. |
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Friday, February 13, 2026 11.00 (Rome) Euler Lecture Hall (Leonardo Building, ICTP) |
Markus Müller |
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| On the origin of quantum many-body scars in Rydberg blockade systems and beyond |
| A fundamental error threshold is the critical error rate of a physical qubit system in quantum error correction (QEC). If the error rate per qubit or quantum gate operation is below this threshold, increasing the size of error-correcting code will exponentially suppress the logical qubit error rate. Thus, the fundamental error threshold is important in realizing a quantum computer. There is a general scheme to map the syndrome decoding into a statistical physics model. Studying phase diagram of the corresponding statistical mechanics model via Monte Carlso simulation, one can study this fundamental error threshold of a QEC code. Here we report our finding on the fundamental error thresholds of 2-dimensional toric code/surface code with various quantum circuit error scenarios. | ||
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Tuesday, February 3, 2026 11.00 (Rome) Euler Lecture Hall (Leonardo Building) |
Se Yong Kim |
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| Fundamental Error Thresholds and $Z(2)$ Statistical Mechanics Models |
| Studying symmetries is an evergreen approach to gaining insights into physical systems. This work addresses how the underlying symmetry structure influences the growth of invariant operators. Operator growth, as captured by Krylov complexity, has found applications from condensed matter theory and quantum chaos to black hole physics and quantum gravity. We introduce the symmetry-resolved Krylov complexity, which captures the time growth of each block into which an operator, invariant under a given symmetry, can be decomposed. We find that, at early times, the complexity of the full operator is equal to the average of the symmetry-resolved contributions. In general, the symmetry-resolved Krylov complexity depends on the charge sector; however, in some cases, this dependence disappears, leading to a form of Krylov complexity equipartition. I will discuss explicit examples for systems of coupled oscillators. | ||
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Tuesday, January 27, 2026 11.00 (Rome) Room 128 (Via Bonomea 265, First Floor) |
Giuseppe Di Giulio |
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| Growth of block diagonal operators and symmetry-resolved Krylov complexity |
| We study modular theory in hyperfinite von Neumann algebras, i.e. in those of type II or type III, from the viewpoint of a subregion charge sector decomposition. We address this symmetry resolution by considering infinite tensor products of finite-dimensional algebras with fixed subregion charge values. An important ingredient is the combination of these algebras using direct integrals. This allows us to obtain the symmetry-resolved modular operator, modular flow, and modular correlation functions for hyperfinite algebras. Our approach establishes a mathematical foundation for recent results on symmetry resolution and modular theory in conformal field theory. Our analysis applies both to charges defined on a continuous range, or on a discrete set. The latter is of interest for condensed matter theory. | ||
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Thursday, January 15, 2026 11.00 (Rome) Room 138 (Via Bonomea 265, First Floor) |
Henri Scheppach |
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| Modular operator, correlation functions and symmetry resolution |
| We derive an exact master equation that captures the dynamics of a quadratic quantum system linearly coupled to a Gaussian environment of the same statistics: the Gaussian Master Equation (GME) [1]. The derivation extends Keldysh contour techniques that have already been employed in the construction of stochastic models for the description of non-Markovian dynamics, such as the stochastic Liouville-von Neumann equation [2].
Unlike previous approaches, our formulation applies universally to both bosonic and fermionic setups, and remains valid in the presence of initial system-environment correlations, allowing for the exact computation of the system’s reduced density matrix across all parameter regimes. Remarkably, the GME shares the same operatorial structure as the Redfield equation and depends on a single kernel – a dressed environment correlation function accounting for all virtual interactions between the system and the environment. This simple structure grants a clear physical interpretation and makes the GME easy to simulate numerically, as we show by applying it to an open system based on two fermions coupled via superconductive pairing. [1] Phys. Rev. Lett. 135, 240401 – Antonio D’Abbruzzo, Vittorio Giovannetti, VC |
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Tuesday, January 13, 2026 11.00 (Rome) Room 128 (Via Bonomea 265, First Floor) |
Vasco Cavina |
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| Non-Markovian open quantum systems: from stochastic models to exact Gaussian master equations |
| 2025 seminars |
| Lipid membranes consist of complex bilayers embedding various lipids and proteins that locally modify the membrane’s elastic properties. Thermal fluctuations of these membranes are known to induce long-range Casimir-like interactions between protein inclusions locally increasing stiffness. In this work, we analyze the distortion of membrane fluctuations surrounding an inclusion through a novel phenomenological framework. We demonstrate that corrections to the pair correlation function of membrane displacement exhibit a universal form at distances exceeding the inclusion size. The phenomenological constants derived from these corrections provide a robust means to determine the Casimir-like interactions between inclusions. This framework accurately reproduces established results for interactions between two disk-shaped inclusions and is easily adapted to other geometries. We successfully applied this technique to the disk-wall configuration and compared the results with standard perturbation theory. By completely resumming the perturbative series for the disk-wall geometry in the large-distance regime using the transfer-matrix method, we obtained results identical to those from our phenomenological approach. Furthermore, we outline a procedure to extract these phenomenological constants, which can be implemented in numerical simulations or potentially extended to experimental data. | ||
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May 14, 2025 11:00 (Rome) Room 139 (Via Bonomea 265, First Floor) |
Damiano Andreghetti |
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| Phenomenological approach to Casimir-like interactions on lipid membranes |
| I will report recent results on the finite temperature dynamical correlation functions of the magnetization operator in the quantum Ising spin chain. First I will present our findings in the Ising quantum field theory describing the scaling limit of the spin chain. Starting from a finite temperature form factor series and a Fredholm determinant representation of the correlators, we explored all space-time and temperature regimes in both the ordered and disordered phases. Apart from confirming existing analytic predictions for the asymptotic behavior of the correlations, we derived a new closed form expression for the correlation length for space-like separations that has some unusual properties: it is a non-analytic function of both the space-time direction and the temperature, and its temperature dependence is non-monotonic. I will then turn to the spin chain, where using methods based on hydrodynamic fluctuations I will show that the correlation length of the order parameter shows similar non-analytic behaviour. This means that, in contrast to the common belief, collective effects induced by quantum fluctuations can persist in the dynamics even at finite temperature. | ||
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Tuesday, December 16, 2025 11.00 (Rome) Room 138 (Via Bonomea 265, First Floor) |
Marton Kormos |
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| Non-analytic behaviour of order parameter correlation lengths in the quantum Ising spin chain |
| The widespread relevance of the Ising model, far beyond ferromagnetism, stems from its simplicity: a collection of agents, e.g. spins, that tend to imitate their neighbors. From the equilibrium liquid-gas transition to motility-induced phase separation in active matter, from opinion dynamics to bistable biochemical systems, countless systems are well described by the concepts underlying the Ising model. Accordingly, when such systems undergo a phase transition the critical behavior typically falls in the Ising universality class, even when they are driven far from thermal equilibrium. I will challenge this picture, by showing that the introduction of spatial diffusion can fundamentally alter the critical dynamics. A new universality class, different from Ising and with genuine non-equilibrium features, emerges in d=3.
In the Brownian Ising model agents with two symmetric internal states, e.g. their spin, are free to diffuse in space. When the total number of agents is conserved, their local density becomes a hydrodynamic mode, potentially affecting the large-scale dynamics of the order parameter. By computing the critical exponents at the lowest non-trivial order in the epsilon-expansion, we demonstrate that near d=4 a new non-equilibrium universality class controls the critical dynamics of the system. Moreover, a symmetry of the system allows to derive a relation between renormalized quantities, valid to all orders in perturbation theory. This relation provides a criterion – similar to the Harris criterion for quenched disorder – to assess the stability of the Ising fixed-point. According to this criterion, the Ising fixed-point is unstable in d=3, while marginal stability is expected in d=2. This identifies our new fixed-point as the natural candidate to describe the critical dynamics of the three-dimensional Brownian Ising Model, and more broadly of any system sharing the same symmetries and conservation laws. |
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December 2, 2025 11.00 (Rome) SISSA (Room 138) |
Mattia Scandolo |
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| Collective behavior of non-equilibrium diffusing spins: the Brownian Ising Model |
| Despite major advances in the theory of quantum integrable systems, computing finite-temperature dynamical correlation functions (analytically or numerically) at generic temperatures, interaction strengths, and particle densities remains an outstanding open problem. By making use of known expressions for the form factors of local observables, I will show that the associated Lehmann sum can be estimated via a simple Monte Carlo sampling scheme, thereby enabling a high-accuracy reconstruction of the correlator’s spacetime dependence. I will focus on the two-point function of the Bose field in the Lieb–Liniger model, a paradigm for quantum integrability. If time permits, I will present preliminary evidence that the same technique also gives access to dynamics after quantum quenches, another longstanding challenge.
The talk is based on the following preprint: https://arxiv.org/abs/2508.17908 |
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November 4, 2025 11.00 (Rome) |
Riccardo Senese |
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| Finite-temperature dynamical correlators in interacting integrable models via Monte Carlo sampling |
| In recent years, monitored quantum systems—i.e., systems driven out of equilibrium by measurements—have attracted considerable attention. The stan- dard framework for these dynamics studies the interplay between unitary evo- lution, governed by a many-body Hamiltonian or random circuit, and a finite density of local projective measurements. Alternative approaches, such as weak- measurement protocols, incorporate the unraveling of Lindblad evolution, where monitoring is applied stochastically to each lattice site. Quantum jumps and their associated measurements have therefore attracted renewed attention in the study of open quantum many-body systems and their measurement-induced phase transitions.
In this talk, I will present results on the metrological aspects of monitored systems under a quantum-jump unraveling, showing that the quantum Fisher information is sensitive to these phase transitions and discussing the resulting metrological implications. I will then examine the impact of imperfect detec- tors and the breakdown of measurement-induced phase transitions due to in- formation loss in a quasi-free fermion model, and highlight out-of-equilibrium properties of minimally monitored systems. |
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October 28, 2025 11.00 (Rome) SISSA, Room 128 |
Giovanni Di Fresco |
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| Monitored Quantum Systems: Metrology, Imperfect Detection, and Local Measurements |
| I will review the information lattice, which we recently introduced as a way to decompose information in a quantum state into local information in position. Using this decomposition allows both universal characterisation of many-body states as well as an informed construction of efficient numerical algorithms for time evolution of many-body states to long times, way beyond the entanglement barrier that limits the time range of matrix product state time evolution.
Refs. |
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14/10/2025, 2025 11.00 (Rome) Stasi Seminar Room (Leonardo Building, ICTP) |
Jens Bardarson |
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| Introduction to the information lattice |
| Self-organization in living and active systems emerges from microscopic interactions, which are governed by symmetries and intrinsic properties of individual constituents. It is possible, however, that spontaneously formed composite units lead to the emergence of large-scale behavior that is completely different from what is expected for the single particles. An example of such occurrences is non-reciprocal active matter, where asymmetric interactions can induce polarity in nonpolar mixtures. To study this phenomenon, I will present a generic class of active matter models with two scalar fields that represent the concentration of molecular species interacting nonreciprocally. We study the stability of the emergent ordered state, showing the existence of true long-range polar order in two dimensions and above, both at the linear level and by including all relevant nonlinearities in the Renormalization Group sense. We achieve this by uncovering a mapping to the Kardar–Parisi–Zhang universality class for the dynamics of fluctuations. This classification allows us to prove a conclusive violation of the Mermin–Wagner theorem and to predict the large-scale behavior of systems with non-reciprocal interactions at any dimension. Moreover, natural systems are often three dimensional, leading to momentum conservation in the bulk. To address this scenario, I will extend this dry system to a wet case, incorporating hydrodynamic interactions in a momentum-conserving fluid. The dynamics of the polar order parameter reveal a fluid-mediated linear instability of the ordered state, which is ultimately stabilized by nonlinear effects in the regime of strong non-reciprocity. This result confirms that the non-equilibrium polar pattern is very robust also to hydrodynamic couplings. |
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Tuesday, September 16, 2025 11.00 (Rome) Room 138 (Via Bonomea 265, First Floor) |
Giulia Pisegna |
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| Emergent polar order in nonpolar mixtures with nonreciprocal interactions |
| Gravity is derived from an action given by the geometrical quantum relative entropy coupling matter fields with geometry. The fundamental idea is to relate the metric of Lorentzian spacetime to a quantum operator, playing the role of an renormalizable effective density matrix and to describe the matter fields topologically, according to a Dirac-Kähler formalism, as the direct sum of a 0-form, a 1-form and a 2-form. While the geometry of spacetime is defined by its metric, the matter fields can be used to define an alternative metric, the metric induced by the matter fields, which geometrically describes the interplay between spacetime and matter. The proposed entropic action is the geometric quantum relative entropy between the metric of spacetime and the metric induced by the matter fields. The modified Einstein equations obtained from this action reduce to the Einstein equations with zero cosmological constant in the regime of low coupling. By introducing the G-field, which acts as a set of Lagrangian multipliers, the proposed entropic action reduces to a dressed Einstein-Hilbert action with an emergent small and positive cosmological constant only dependent on the G-field. The obtained equations of modified gravity remain second order in the metric and in the G-field. A canonical quantization of this field theory could bring new insights into quantum gravity while further research might clarify the role that the G-field could have for dark matter. We furthermore show that the geometrical quantum relative entropy associated to the Schwarzschild metric, which provides an approximate solution of the modified gravity equations, follows the area law for large Schwarzschild radius. Bianconi, G., 2025. Gravity from entropy. Physical Review D, 111(6), p.066001. |
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Tuesday, July 1, 2025 11.00 (Rome) Lagrange Lecture Hall Room (Leonardo Building, ICTP) |
Ginestra Bianconi |
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| Gravity from entropy |
| We explain how accurate large-deviations estimates allow to compute the microcanonical partition function of the Discrete Non-Linear Schroedinger Equation (DNLSE), revealing all the peculiarities of the high-energy localized phase, from ensemble inequivalence to the mixed first/second order nature of the transition. The same large-deviation approach is then applied to the calculation of the canonical partition function for free bosons, highlighting the analogies and differences between the transition in the DNLSE and Bose-Einstein condensation. |
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June 17, 2025 11:00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Giacomo Gradenigo |
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| Localization transition and ensemble inequivalence in two paradigmatic cases: the Discrete Non-Linear Schroedinger Equation and Bose-Einstein condensation |
| Driven quantum systems can lead to novel and interesting phases of matter. In this talk, we will summarize recent results on phase structures and phase transitions in the context of driven Conformal Field Theories in two dimensions and beyond. In particular, we will discuss how non-trivial (dynamical) phases emerge that can be classified according to the conjugacy classes of the corresponding sl(2,R) transformation. We will also explain how a geometric (more generally, Holographic) dual description encodes the information of these phases and how the experience of a bulk observer is encoded in the CFT Hamiltonian. Finally, we will conclude with potential future directions. | ||
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Tuesday, May 27, 2025 14.00 (Rome) room 128 (SISSA, via Bonomea) |
Arnab Kundu |
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| Driven CFTs, Dynamical Phase Transitions & Geometric Duals |
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Tuesday, May 27, 2025 11:00am room 128 (SISSA, via Bonomea) |
Duncan Haldane |
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| Geometry and fluid dynamics of the quantum Hall effect |
| The vacuum state of a quantum field theory contains an infinite amount of quantum entanglement. One active area of research is to probe and exploit the quantum properties of the vacuum by letting non-relativistic systems interact with a quantum field and thus inherit such properties. An example of this is the “entanglement harvesting” protocol, where two qubits interacting with the quantum field time-evolve to become entangled. This is an LOCC process, so the origin of the entanglement must be in the vacuum state. Recently, it has been shown that qualitatively different quantum resources can also be generated into non-relativistic systems by a variant of the harvesting protocol. Through the interaction, the system can evolve to a magic state. I will review the entanglement harvesting protocol, discuss the novel “magic harvesting” protocols, and speculate what lessons could be drawn. | ||
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Tuesday, May 20, 2025 11.00 (Rome) room 128 (SISSA, via Bonomea) |
Esko Keski-Vakkuri |
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| Magic from the Vacuum? |
| Rydberg simulators, superconducting qubit arrays and other quantum simulation platforms are increasingly able to simulate isolated quantum many-body dynamics in two spatial dimensions, and explore uncharted territory for theory. For example, recent experiments study order parameter dynamics in both slow ramps and (fast) quenches involving phase transitions, thereby placing the physics of quantum coarsening in the experimental realm. Here, we present a theory for this non-equilibrium dynamics. | ||
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Monday, May 19, 2025 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Federico Balducci |
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| Symmetry re-breaking and effective theory of quantum coarsening |
| I will present a summary of a program of work that began in 2023 with several collaborators and is still ongoing. Our main goal has been to develop the form factor program for integrable quantum field theories (IQFTs) in the presence of irrelevant perturbations. Our main result to date is a detailed understanding of the structure of minimal form factors (MMFs), the building blocks of higher particle matrix elements. Through this work, we have found new results even for more standard IQFTs and have examined more deeply what the fundamental physical requirements in the construction of MFFs are. However, higher particle form factors pose serious challenges for various reasons which I will also discuss. | ||
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Tuesday, May 13, 2025 11.00 (Rome) room 138 (SISSA, via Bonomea) |
Olalla Castro-Alvaredo |
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| Irrelevant Perturbations in Integrable Quantum Field Theory: Completing the Bootstrap Program |
| We present a multimethod investigation into the nature of the recently reported quantum spin liquid (QSL) phase in the spin-1/2 Heisenberg antiferromagnet on the Shastry-Sutherland lattice. Acomprehensive projective symmetry group classification of fermionic mean-field Ansätze on this lattice yields 46 U(1) and 80 ℤ2 states. Motivated by density-matrix renormalization group (DMRG)calculations suggesting that the Shastry-Sutherland model and the square-lattice J1-J2 Heisenberg antiferromagnet putatively share the same QSL phase, we establish a mapping of our Ansätze to those of the square lattice. This enables us to identify the equivalent of the square-lattice QSL (Z2Azz13) in the Shastry-Sutherland system. Employing state-of-the-art variational Monte Carlo calculations with Gutzwiller-projected wavefunctions improved upon by Lanczos steps, we demonstrate the excellent agreement of energies and correlators between a gapless (Dirac) ℤ2 spin liquid — characterized by only few parameters — and approaches based on neural quantum states and DMRG. Furthermore, the real-space spin-spin correlations are shown to decay with the same power law as in the J1-J2 square lattice model, which also hosts a ℤ2 Dirac spin liquid. Finally, we apply the recently developed Keldysh formulation of the pseudo-fermion functional renormalization group to compute the dynamical spin structure factor; these correlations exhibit the features expected due to Dirac cones in the excitation spectrum, thus providing strong independent evidence for a Dirac QSL ground state. Our finding of a d-wave pairing ℤ2 Dirac QSL is consistent with the recently observed signatures of QSL behavior in Pr2Ga2BeO7 and outlines predictions for future experiments. | ||
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Today, May 6, 2025 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Rupak Majumder |
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| Evidence for a ℤ2 Dirac spin liquid in the generalized Shastry-Sutherland model |
| The study of cooperative effects in spontaneous radiation emission by atomic ensembles has attracted great attention since Dicke’s 1954 seminal article on superradiance. The phenomenon of subradiance, on the other hand, is less understood, and has been observed less than 10 years ago (by Guerin, Araújo and Kaiser), who detected very slow decay, with lifetimes of the order of 100 times the natural lifetime of individual (independent) atoms. By using random matrices, we investigate the features of the spontaneous decay of a dilute cold atomic cloud, and analyze both super- and subradiant states. | ||
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Tuesday, April 1, 2025 11.00 (Rome) room 138 (SISSA, via Bonomea) |
Saverio Pascazio |
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| Super and subradiance in cold atomic clouds: cooperative decay modes and random states |
| Gauge theories are the back-bone of our understanding of nature at the most fundamental level as captured by the standard model. Despite their elegance and conceptual simplicity, gauge theories have historically represented a major computational challenge in many-body theory – including, for instance, the real-time dynamics describing heavy-ion collisions at colliders, which is inaccessible to classical simulations based on Monte Carlo sampling. These challenges have motivated a flurry of theoretical activity over the last ten years, devoted at developing strategies for the quantum simulation of their discretized version – lattice gauge theories. In this first part of the talk, I will review the status of the field, highlighting potential applications as well as roadblocks, and discussing the first realization of gauge theory dynamics in a trapped ion quantum computer. In the second part of the talk, I will show how Rydberg atoms trapped in optical tweezers offer unprecedented opportunities for the realization of lattice gauge theories in AMO systems. In particular, I will describe how recent experiments have already realized the real-time dynamics of the lattice Schwinger model (the one-dimensional version of quantum electrodynamics) in the presence of a topological angle, at system sizes at the boundaries of what is achievable with the best known classical algorithms. Finally, I will do a 180 degree turn, and show how experimentally-realistic Abelian and non-Abelian lattice gauge theories provide unheralded insights on the breakdown of thermalization in strongly interacting quantum systems. | ||
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Tuesday, March 25, 2025 11.00 (Part 1) and 14.00 (Part 2) (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Marcello Dalmonte |
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| Quantum simulating lattice gauge theories: ‘particle physics’ with Rydberg atom arrays |
| A trapped-ion system is one of the most promising platforms for quantum computation, simulation, precision measurements, and quantum networks. In such a system, a high level of control can be achieved, which is essential for solving hard-to-compute physics problems with very high accuracy. In particular, the quantum simulation of complex physics models is one of the direct applications of such systems. A key question in quantum simulation is the validity of simulation results. Significant progress has been made in recent years in predicting the Hamiltonian that governs the time evolution of input states. However, the experimental implementation of these predictions has been technically challenging for large-scale quantum systems. In this seminar, I will present recent results from our lab on learning system Hamiltonians via randomized measurements for systems of up to 51 qubits. Finally, I will demonstrate how to predict simulation results from the learned Hamiltonians. | ||
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Tuesday, March 18, 2025 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Manoj K. Joshi |
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| Hamiltonian learning and verification of quantum simulators |
| The out-of-equilibrium dynamics of many-body monitored systems has attracted a lot of attention in the last years due to the possibility of the onset of measurement-induced-phase transitions. In this context replica trick has proven to be an effective way to investigate the physics of such systems, by taking into account Born’s rule weighting of the measurement outcomes. On the other hand, by investigating mean-field models, other aingle-replica approaches are possibile. In particular we examine a fully-connected, noisy version of the all-to-all Heisenberg model subjected to monitoring. We develop an effective mean-field replica field theory in the limit of large $N$ and we ar able to take the replica limit exactly: surprisingly, the replica-symmetry transition disappears in such limit, as the Landau free energy develops a non-analiticity. We check this result by considering a different approach which bypasses the replica limit. Similarly, single-replica methods can be applied to the monitored version of the (clean) Lipkin-Meshkov-Glick model: in this case, a phase transition arises already at the single-operator level, due to the non-commutativity of the large-time and large-$N$ limit. | ||
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Tuesday, March 11, 2025 11.00 (Rome) room 128 (SISSA, via Bonomea) |
Guido Giachetti |
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| Monitored Mean-Field Systems: Replica Approach and Beyond |
| The study of entanglement Hamiltonians in many-body ground states has received increased attention recently, both on the theoretical and experimental side. The seminal results of Bisognano and Wichmann and its generalizations yield explicit results for relativistic or conformal field theories in various geometries. However, it is far from obvious how these results generalize to lattice systems, where the relativistic symmetry is explicitly broken. While the situation for homogeneous chains with an effective low-energy CFT description is well understood, the inhomogeneous setting remains much less explored. In my talk I will present recent results for the entanglement Hamiltonian in free-fermion systems with particular forms of inhomogeneity, and show how these can be reconciled with a CFT treatment of the problem. | ||
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Tuesday, March 4, 2025 11.00 A.M room 138 (SISSA, via Bonomea) |
Viktor Eisler |
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| Entanglement Hamiltonian for inhomogeneous free-fermion systems |
| Non-Markovian dynamics, characterized by memory effects and information backflow, play a crucial role in many quantum systems, influencing properties such as coherence and entanglement. In this talk, we explore how non-Markovianity emerges in different settings, ranging from application to quantum devices to theoretical models. First, we analyze a monitored free-fermion system where noise in an ancilla can unexpectedly enhance entanglement, highlighting the interplay between measurement-induced dynamics and memory effects. Second, we characterize non-Markovianity in a simple qubit-impurity system, studying how it can be quantified via simple spectroscopic. Finally, we investigate how the ground state of a many-body Hamiltonian can be studied via the dissipative dynamics of an open quantum system. | ||
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Tuesday, February 25, 2025 11.00 A.M Luigi Stasi Seminar Room (Leonardo Building, ICTP) |
Giuliano Chiriacò |
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| Exploiting memory effects and dissipative dynamics in quantum systems |
| Programmable arrays of ultracold Rydberg atoms offer an intriguing platform for quantum information processing. In this talk, I will introduce two novel architectures designed to address scalability challenges for neutral atoms trapped in optical tweezers. The first architecture is a low-vibration, high-optical-access cryogenic platform, developed during my time at JILA, which significantly enhances the atom vacuum lifetime. In this system, we demonstrate a 3000-second atom trap lifetime, enabling the creation of defect-free atom arrays with thousands of qubits. Additionally, we achieve ground-state qubit manipulation using an integrated microwave antenna and demonstrate two-photon coherent control of Rydberg states. The second architecture is currently under construction at the University of Trieste. This system integrates three key components: a quantum computing unit for executing arbitrary operations, a tweezer-cavity interface for cavity quantum electrodynamics (cQED) and quantum networking experiments, and an atom reservoir to enable fast experimental cycle times and uninterrupted operations. |
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Tuesday, February 11, 2025 11.00 a.m (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Matteo Marinelli |
|---|---|---|
| Novel Platforms for Quantum Information Processing with Rydberg Atom Arrays |
| According to conventional wisdom, a macroscopic system placed in an environment with a different temperature relaxes (i.e., warms up or cools down) to the temperature of the surroundings. This relaxation is mediated by the flow of heat that is set only by the temperature difference. However, when rapid changes in temperature push a system far from equilibrium, thermal relaxation becomes asymmetric, which was predicted theoretically [1,2] and recently confirmed experimentally [3]. That is, under quite general conditions, heating is in fact faster than cooling. I will first introduce the relaxation asymmetry in reversible [1,3] and detailed-balance violating [2] finite-dimensional systems. In the main part of the talk I will present a rigorous formulation of thermal relaxation in the framework of hydrodynamic fluctuation theory for short- and long-range interacting systems, respectively. I will show that the asymmetry persists in the hydrodynamic limit and that in contrast to finite-dimensions a “true” close-to-equilibrium thermal quench with symmetric heating and cooling at all times does not exist [4].
References: |
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Tuesday, January 28, 2025 11.00 (Rome) room 128 (SISSA, via Bonomea) |
Aljaz Godec |
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| Thermal relaxation asymmetry: from single molecules to hydrodynamic fluctuations |
| The six-vertex model with domain wall boundary conditions exhibits spatial phase separation, with the emergence of regions of order and disorder, sharply separated by a smooth curve, called arctic curve. After reviewing the state of the art the field, including its connection to quantum quenches, we focus on the emptiness formation probability (EFP), a non-local correlation function testing the order-disorder interface, and its fluctuations. While at the free-fermiont point the behaviour of EFP is known in full detail, much less can be said for generic values of $\Delta$. Here we specialize to the ice point, $\Delta=1/2$, where all the Boltzmann weights are equal. We build an explicit and exact, although still conjectural, expression for the EFP as the Fredholm determinant of some linear integral operator. We study the behaviour of the obtained representation in the scaling limit. In particular, as the geometric parameters of the EFP are tuned to the vicinity of the arctic curve, we obtain the GUE Tracy-Widom distribution (just as in the $\Delta=0$ case). In other words, interface fluctuations around the arctic curve fall into the Kardar-Parisi-Zhang universality class.
Joint work with A. Pronko – ArXiv:2405.04358 – Nucl. Phys. B (2024) |
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Tuesday, January 21, 2025 11.00 (Rome) |
Filippo Colomo |
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| Tracy-Widom distribution in the six-vertex model |
| Janus particles are artificial colloids characterised by inhomogeneous physical and chemical properties across their surface. This inhomogeneity, together with the hydrodynamic interactions with the surrounding fluid, allows them to display a very rich phenomenology. In particular, a phoretic Janus colloid produces (or consumes) chemicals, self-propels, drifts along chemical gradients, and rotates its intrinsic polarity to align with these gradients. Accordingly, their collective behaviour is controlled by the interplay of the particles’ position and orientation. These features make Janus colloids good candidates for engineering and reproducing active matter systems. As a result the connection from microscopic to continuum theories through coarse-graining couples densities and polarisation fields. We show that these couplings render the homogenous disordered state unstable to small perturbations through a variety of instabilities. Moreover, a multicomponent mixture of Janus colloids with distinct catalytic coats and phoretic mobilities is a promising theoretical system to explore the collective behaviour arising from nonreciprocal interactions. For example, when the polar fields relaxes quickly, they can be eliminated in favour of the density fields to obtain a microscopic realisation of the Nonreciprocal Cahn–Hilliard model of nonreciprocal interactions between two scalar densities. | ||
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Tuesday, January 14, 2025 11.00 (Rome) room 128 (SISSA, via Bonomea) |
Gennaro Tucci |
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| Collective dynamics of a mixture of phoretic Janus colloids |
| 2024 seminars |
| We construct an efficient scheme for the quantum and classical simulation of non-Abelian lattice gauge theories beyond one spatial dimension. First, we show how to reformulate two-dimensional non-Abelian lattice gauge theories in terms of loop variables and conjugate loop electric fields, using canonical transformations on the initial degrees of freedom. By explicitly solving the Gauss law on the lattice, we efficiently rewrite the Hamiltonian in terms of physical independent quantities, without any constraint left in the case of periodic boundary conditions. This dualization procedure simplifies the magnetic part of the Hamiltonian, while introducing non-localities in the electric terms. Then, we determine a convenient representation of the Hamiltonian by choosing the local basis for small and big loops variationally, minimizing the truncation error and allowing us to compute the running of the coupling with finite resources for all coupling regimes on small tori. This method enables computations at arbitrary values of the bare coupling and lattice spacing with current quantum computers/simulators and tensor-network calculations, in regimes otherwise inaccessible. | ||
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Tuesday, December 17, 2024 11.15 (Rome) room 128 (SISSA, via Bonomea) |
Pierpaolo Fontana |
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| An efficient finite-resource formulation of non-Abelian lattice gauge theories beyond one dimension |
| The dynamics of a phase-separating binary mixture is characterized by the formation of droplets of high material concentration separated by an interface from a dilute background. While in passive systems these interfaces evolve to minimize their total area, in driven and active mixtures their behavior is altered by the presence of a continuous energy consumptions. In this talk, we will explore the consequences of such energy consumption on phase separation in terms of its effect on the interface dynamics. We will then see the implications of this dynamics for the physics of thermally driven and chemically active binary mixtures. |
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Tuesday, December 10, 2024 11.00 (Rome) room 138 (SISSA, via Bonomea) |
Jacopo Romano |
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| Interface dynamics in driven and active binary mixtures |
| I will review some recent works on the application of RG ideas to localization problems in cases in which they have not been applied before. In particular, I will show what happens to the flow in the Anderson model when the number of dimensions tend to infinity, and how to reconstruct the flow from numerical data using the finite-size scaling theory; I will also show how different models of MBL can present different RG flows which reflect different mechanisms for the localization-ETH transition.
Work based on: |
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Tuesday, December 3, 2024 11.00 (Rome) ICTP, Leonardo Building, Luigi Stasi Seminar Room |
Antonello Scardicchio |
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| Recent progress on renormalisation group analysis of Anderson and MBL models |
| Limit-cycle or time-crystal phases, in which the order parameter retains a periodic motion in time, are non-equilibrium phases. They are therefore expected to display phenomena that fall beyond equilibrium classifications. We study such phenomena in paradigmatic O(N) models. Once suitably driven out of equilibrium, they develop instabilities towards limit-cycle long-range orders, which emerge in driven quantum systems and solid-state platforms, as well as nonreciprocal active matter. I will discuss realization in existing platforms, but also new implementations in driven magnets.
I will describe the complete phase diagram beyond mean-field, which hosts new type of phase transitions towards limit cycles, associated to new non-equilibrium universality classes. Finally, I will discuss why such phases generically display Kardar-Parisi-Zhang physics and generalization of it. |
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Tuesday, November 26, 2024 11.00 (Rome) room 128 (SISSA, via Bonomea) |
Romain Daviet |
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| Universal non-equilibrium behaviors of limit-cycle phases |
| Tomita-Takesaki modular theory is a tool in the mathematical formulation of quantum field theory, which is used in the computation of (relative) entropies between subsystems, for example. Finding analytic solutions for modular operators is challenging and only very few cases — mostly for massless fields — are known. I will give a brief overview on modular operators and mention some papers that give a good introduction to the topic from a perspective motivated by physics. Then I will show some results obtained with a numerical approximation scheme for the modular operator of local subalgebras in linear quantum fields of massive bosons and fermions. The numerical method is tested with the known results of right wedges in 2-dimensional Minkowski spacetime. Our numerical results for double cones showed that the modular operator indeed depends on the mass parameter (against previous expectations) and is “non-local”. For fermions with small masses, we also developed a perturbative technique to get first order corrections to the massless operator. The results are from joined projects with Henning Bostelmann, Daniela Cadamuro, and Markus Fröb. First numerical results on bosons (arXiv:2209.04681) were published 2023; the analytic computations for fermions with small mass (arXiv:2312.04629) are accepted for publication; and another paper is in final preparation. |
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Tuesday, November 19, 2024 11.00 (Rome) room 128 (SISSA, Via Bonomea) |
Christoph Minz |
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| On the mass dependence of modular operators over double cone regions in QFT |
| The propagation of wave packets with unit charge provides valuable information about the dispersion relation of elementary particles. In strongly correlated systems that exhibit charge fractionalization, one expects a single wave packet to split into multiple humps that carry fractional charges. In this talk I will discuss the time evolution in a critical fermionic chain starting from an initial state where a Gaussian wave packet is prepared with arbitrary momentum, not restricted to the low-energy limit. I will show that the dynamics is well described by nonlinear Luttinger liquid theory, and the fractional charges observed in real time provide a direct measurement of interaction parameters that govern various threshold singularities of dynamic response functions in the frequency domain. Moreover, at high energies, the evolution of a wave packet with unit charge reveals signatures of composite excitations containing two-particle bound states. Our work paves the way for precision tests of nonlinear Luttinger liquid effects in time-resolved experiments in quantum wires and ultracold-atom platforms. | ||
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November 12, 2024 11.30 Aula D (Ex-SISSA building, Miramare) |
Rodrigo Pereira |
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| Nonlinear Effects on Charge Fractionalization in Critical Chains |
| Integrable unitary circuits can be seen as a Trotter formulation of some integrable continuous time Hamiltonian. Their importance lies in the potential to use analytical methods to compute physical observables, like correlation functions and mean particle current. I will divide this talk into two parts: discrete and continuous dynamical evolution of a quantum system. First, I will review how the dynamic of an integrable quantum circuit with two-step Floquet dynamics, under both periodic and open boundary conditions, relates to the transfer matrix formalism. Using this construction, I will build different quantum circuits by taking the elementary gate as the tensor product of two R-matrices of a spin ½ chain. By using Sklyanin’s reflection algebra, I will address the question of which cases have the gate corresponding to the boundary matrix also factorized. In the second part of the talk, I will focus on continuous time evolution and interpret the boundary terms in the Lindbladian framework. For specific parameter choices, these solutions correspond to an open quantum chain with particles being injected or removed from the boundaries of the spin chain.
Based on arXiv:2406.12695 with T. Prosen. |
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October 8, 2024 11.00 am Room 128 (SISSA, Via Bonomea) |
Chiara Paletta |
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| Integrability of open^2 quantum circuits |
| Symmetry-protected topological phases have fundamentally changed our understanding of quantum matter. An archetypal example of such a quantum phase of matter is the Haldane phase, containing the spin-1 Heisenberg chain. The intrinsic quantum nature of such phases, however, often makes it challenging to study them using classical means. Here, we use trapped-ion qutrits to natively engineer spin-1 chains within the Haldane phase. Using a scalable, deterministic procedure to prepare the Affleck-Kennedy-Lieb-Tasaki (AKLT) state within the Haldane phase, we study the topological features of this system on a qudit quantum processor. Notably, we verify the long-range string order of the state, despite its short-range correlations, and observe spin fractionalization of the physical spin-1 particles into effective qubits at the chain edges, a defining feature of this system. The native realization of Haldane physics on a qudit quantum processor and the scalable preparation procedures open the door to the efficient exploration of a wide range of systems beyond spin-1/2
arXiv:2408.04702 Co-authors: C. L. Edmunds, E. Rico, I. Arrazola, G. K. Brennen, M. Meth, R. Blatt, M. Ringbauer |
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September 24, 2024 11:00am |
Enrique Rico |
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| Constructing the spin-1 Haldane phase on a qudit quantum processor |
| The classical simulation of highly entangling quantum dynamics is conjectured to be generically hard. Thus, recently discovered measurement-induced transitions between highly entangling and low-entanglement dynamics are phase transitions in classical simulability. Here, we study simulability transitions beyond entanglement: noting that some highly entangling dynamics (e.g., integrable systems or Clifford circuits) are easy to classically simulate, thus requiring “magic”—a subtle form of quantum resource—to achieve computational hardness, we ask how the dynamics of magic competes with measurements. We study the resulting “dynamical magic transitions” focusing on random monitored Clifford circuits doped by T gates (injecting magic). We identify dynamical “stabilizer purification”—the collapse of a superposition of stabilizer states by measurements—as the mechanism driving this transition. We find cases where transitions in magic and entanglement coincide, but also others with a magic and simulability transition in a highly (volume-law) entangled phase. In establishing our results, we use Pauli-based computation, a scheme distilling the quantum essence of the dynamics to a magic state register subject to mutually commuting measurements. We link stabilizer purification to “magic fragmentation” wherein these measurements separate into disjoint, O(1)-weight blocks, and relate this to the spread of magic in the original circuit becoming arrested. | ||
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September 17, 2024 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Benjamin Beri |
|---|---|---|
| Dynamical Magic Transitions in Monitored Clifford+T Circuits |
| We all know that entanglement is important in quantum mechanics. However, every form of complex behavior, including that which is responsible for quantum advantage, needs a second ingredient, colloquiually known as magic. In this talk we will show that quantum advantage and quantum complexity arise from the conspiration and interplay of two entropic resources, Entanglement Entropy (EE) and Stabilizer Entropy (SE). In particular, quantum complex behavior arises when stabilizer entropy gets scrambled around. We will provide an introduction to the resource theory of SE and applications in quantum many-body systems, quantum metrology, black-hole physics, and foundations of quantum mechanics. | ||
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September 10, 2024 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Alioscia Hamma |
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| Complexity, Entanglement, and Stabilizer entropy |
| The Sum of Powers of Principal Minors (SPPM) of matrices is used in calculating the Rényi entropy in fermionic systems, the partition function of the Hubbard model, and the partition function of weighted rooted spanning forests when the matrix in question is the graph’s Laplacian. It is likely that no polynomial-time solution exists to estimate SPPM. Initially, I will discuss how the Rényi (Shannon) entropy in quantum chains can identify different phases and classify universality classes. The core of this talk will introduce a Grassmann representation for a generic matrix SPPM problem. Leveraging this representation, I will outline three distinct yet compatible mean-field approximations, providing an accurate estimation of the Rényi entropy for the Ising chain. Lastly, I will discuss how the SPPM problem can be viewed as the partition function for rooted spanning forests and use the cavity method (belief propagation) to calculate it. | ||
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Tuesday, July 2, 2024 11.00 (Rome) |
M. Ali Rajabpour |
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| Minors or: how I learned to stop worrying and love the exponential |
| Statistical physics has emerged as a powerful tool for studying many-particle interacting systems. These interactions can be mainly categorized as short-range (SR) and long-range (LR) interactions. While the equilibrium properties of the SR systems are well understood, LR systems remain less explored. The 1d Riesz gas model where the particles interact via power-law potential provides a natural setting to study the properties of SR and LR systems. We discuss how the low-temperature equilibrium properties of coarse-grained quantities behave as the interactions are modified from short-range to long-range. Specifically, we focus on density profiles, edge particle statistics, gap statistics and Index distribution. Furthermore, we compute the pressure and the bulk modulus for SR case of the Riesz gas. | ||
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Thursday, June 20, 2024 11.00 (Rome) Room 138 (SISSA, via Bonomea) |
Jitendra Kethepalli |
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| Equilibrium properties of confined Riesz gas |
| Reciprocity is a hallmark of thermal equilibrium, but ubiquitously broken in far-from-equilibrium systems. I will give some insights into how nonreciprocal interactions can fundamentally affect the phases and fluctuations of many-body systems. First, in binary fluids, nonreciprocal coupling between fluid components can cause the emergence of travelling waves through PT symmetry-breaking phase transitions. Using a nonreciprocal field model, we show that fluctuations not only inflate, as in equilibrium criticality, but also develop an asymptotically increasing time-reversal asymmetry [1-3]. The formation of dissipative patterns and the emergence of irreversible fluctuations can both be attributed to a mechanism of mode coupling in the vicinity of critical exception points. For a nonreciprocal Cahn-Hilliard model, we show that this manifests itself in actively propelled interfaces, whose dynamics can be mapped to the motion of a single microswimmer [3]. Second, introducing nonreciprocal coupling in the two-dimensional XY model, we discuss how nonreciprocity can induce spatio-temporal chaos that can be regarded as self-generated noise.
[1] Suchanek, Kroy & SAML, Irreversible mesoscale fluctuations herald the emergence of dynamical phases, Phys. Rev. Lett. 131, 258302 (2023) |
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Tuesday, June 18, 2024 11.00 (Rome) Room 138 (SISSA, via Bonomea) |
Sarah Loos |
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| About fluctuating many-body systems with nonreciprocal interactions |
| Monitored quantum systems offer a new setting to explore quantum many-body physics away from equilibrium. Fueled by the experimental progress in building quantum simulators, their study sheds light on the dynamics of quantum information and entanglement in open quantum systems. In addition, monitored systems also offer the ability to dynamically tailor states with topological order. In this talk I consider a system of fermions evolving with a non-interacting Hamiltonian and subjected to competing measurements. The unitary evolution builds entanglement while repeated measurements disentangle the local degrees of freedom resulting in a measurement induced phase transition (MIPT). We employ a generalized measurement scheme with variable coupling between the system and detector. When the coupling is strong – this is akin to a projective measurement. When the coupling is weak, this describes continuous measurements where the information extracted by the detector and the duration of the measurement are reduced to zero simultaneously. This scheme allows us to study how the coupling between system and detector alters the MIPT. To gain further insight into the transition, we study the deterministic dynamics which arises when only a single detector outcome is retained. This post selected limit is governed by a non-hermitian Hamiltonian. Finally, I introduce a partial-post-selection procedure that interpolates between the monitored dynamics and the post selected limit, and discuss the evolution of the MIPT between these two limits | ||
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Tuesday, June 11, 2024 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Dganit Meidan |
|---|---|---|
| Dynamics of non-interacting fermions subjected to generalized measurement schemes |
| I will present our investigations of the rich quantum phase diagram of Wegner’s theory of discrete Ising gauge fields interacting with U(1) symmetric single-component fermion matter hopping on a two-dimensional square lattice. At half filling, I will present evidence of the deconfined Dirac semimetal and staggered Mott insulator phases. I will summarize our numerical investigations of the nature of an exotic phase transition between these phases. I will conjecture a u(1) deconfined criticality scenario, propose a corresponding low-energy effective field theory of the exotic quantum critical point in the two-dimensional limit. I will also identify several shortcomings of this conjecture. | ||
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Tuesday, June 4, 2024 11.00 (Rome) Luigi Stasi Seminar Room (Leonardo Building, second floor, ICTP) |
Sergej Moroz |
|---|---|---|
| In pursuit of deconfined quantum criticality in Ising gauge theory entangled with single-component fermions |
| I will present a thorough discussion of the ordering kinetics of ferromagnetic systems with long-range interactions decaying with distance as r^(-α), for any and in any spatial dimension d. I will consider two paradigmatic models: the voter model and the Ising one. The former is solvable in any dimension [1-3]. The latter can be studied analytically in one dimension using scaling arguments [4], or in a continuum (Ginzburg-Landau) approach [5,6]. Besides that, numerical simulations are also available. In general, the kinetics is characterized by the formation and growth of domains. In both models there is an upper critical value α_SR of α, such that for α>α_SR the model behaves as the corresponding one with short-range interactions (e.g. among nearest-neighbors). In particular, the characteristic size L(t) of the coarsening domains grows as L(t)∝t^(1/2). There also exists a lower critical value α_LR such that some mean-field features (corresponding to α=0), specifically the absence of a real coarsening regime, are displayed for α
[1] F. Corberi, and C. Castellano, arXiv:2309.16517 (to appear in J.Phys: Complexity, 2024). |
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Tuesday, May 28, 2024 11.00 (Rome) room 138 (SISSA, via Bonomea) |
Federico Corberi |
|---|---|---|
| Phase-ordering kinetics in ferromagnetic systems with long-range interactions |
| I will present some of the recent results obtained together with Stefano Carignano about the scaling of the temporal entropies. We will confirm the CFT predictions with calculations based on tensor networks. | ||
| 📅 🕓 🚪 |
May 23, 2024, 2024 11.00 (Rome) room 128 (SISSA, via Bonomea) |
Luca Tagliacozzo |
|---|---|---|
| Temporal entropies and conformal field theories |
| For over five decades, ecologists have gathered census data across various ecosystems globally, including tropical forests, coral reefs, and plankton communities. Despite the distinct biological and environmental characteristics of these communities, universal macroecological patterns, often described by power laws, have consistently emerged. This indicates the presence of ecological processes that transcend the specific details of each system, leading to the formation of these general patterns. S |