Julian Sonner
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View article: Holography of K-complexity: Switchbacks and Shockwaves
Holography of K-complexity: Switchbacks and Shockwaves Open
In this paper we study Krylov complexity in the presence of single and multiple operators in the DSSYK model, where we can use the analytical techniques coming from chord diagrammatics. One of the results we obtain is that it showcases the…
View article: Driven nonunitary dynamics of quantum critical systems
Driven nonunitary dynamics of quantum critical systems Open
We investigate the interplay between unitary and non-unitary driven many-body dynamics in (1+1)-dimensional quantum critical systems described by conformal field theory (CFT). By formulating a coherent state approach, we demonstrate that t…
View article: Operator K-complexity in DSSYK: Krylov complexity equals bulk length
Operator K-complexity in DSSYK: Krylov complexity equals bulk length Open
A bstract In this paper we study the notion of complexity under time evolution in chaotic quantum systems with holographic duals. Continuing on from our previous work, we turn our attention to the issue of Krylov complexity upon the insert…
View article: Krylov Complexity
Krylov Complexity Open
We introduce and review a new complexity measure, called `Krylov complexity', which takes its origins in the field of quantum-chaotic dynamics, serving as a canonical measure of operator growth and spreading. Krylov complexity, underpinned…
View article: Quantum chaos in Liouville CFT
Quantum chaos in Liouville CFT Open
A bstract Fast scrambling is a distinctive feature of quantum gravity, which by means of holography is closely tied to the behaviour of large- c conformal field theories. We study this phenomenon in the context of semiclassical Liouville t…
View article: Gravity as a mesoscopic system
Gravity as a mesoscopic system Open
A bstract We employ a probabilistic mesoscopic description to draw conceptual and quantitative analogies between Brownian motion and late-time fluctuations of thermal correlation functions in generic chaotic systems respecting ETH. In this…
View article: Measuring Rényi entropy using a projected Loschmidt echo
Measuring Rényi entropy using a projected Loschmidt echo Open
We present efficient and practical protocols to measure the second Rényi entropy (RE), whose exponential is known as the purity. We achieve this by establishing a direct connection to a Loschmidt echo (LE) type measurement sequence, applic…
View article: Operator K-complexity in DSSYK: Krylov complexity equals bulk length
Operator K-complexity in DSSYK: Krylov complexity equals bulk length Open
In this paper we study the notion of complexity under time evolution in chaotic quantum systems with holographic duals. Continuing on from our previous work, we turn our attention to the issue of Krylov complexity upon the insertion of a c…
View article: Quantum simulation of the Sachdev-Ye-Kitaev model using time-dependent disorder in optical cavities
Quantum simulation of the Sachdev-Ye-Kitaev model using time-dependent disorder in optical cavities Open
The Sachdev-Ye-Kitaev (SYK) model is a paradigm for extreme quantum chaos, non-Fermi-liquid behavior, and holographic matter. Yet, the dense random all-to-all interactions that characterize it are an extreme challenge for realistic laborat…
View article: Approximate CFTs and random tensor models
Approximate CFTs and random tensor models Open
A bstract A key issue in both the field of quantum chaos and quantum gravity is an effective description of chaotic conformal field theories (CFTs), that is CFTs that have a quantum ergodic limit. We develop a framework incorporating the c…
View article: Gravity as a mesoscopic system
Gravity as a mesoscopic system Open
We employ a probabilistic mesoscopic description to draw conceptual and quantitative analogies between Brownian motion and late-time fluctuations of thermal correlation functions in generic chaotic systems respecting ETH. In this framework…
View article: Quantum chaos on edge
Quantum chaos on edge Open
Recently, the physics of many-body quantum chaotic systems close to their ground states has come under intensified scrutiny. Such studies are motivated by the emergence of model systems exhibiting chaotic fluctuations throughout the entire…
View article: Quantum Chaos in Liouville CFT
Quantum Chaos in Liouville CFT Open
Fast scrambling is a distinctive feature of quantum gravity, which by means of holography is closely tied to the behaviour of large$-c$ conformal field theories. We study this phenomenon in the context of semiclassical Liouville theory, pr…
View article: The influence functional in open holography: entanglement and Rényi entropies
The influence functional in open holography: entanglement and Rényi entropies Open
A bstract Open quantum systems are defined as ordinary unitary quantum theories coupled to a set of external degrees of freedom, which are introduced to take on the rôle of an unobserved environment. Here we study examples of open quantum …
View article: Hilbert Space Diffusion in Systems with Approximate Symmetries
Hilbert Space Diffusion in Systems with Approximate Symmetries Open
Random matrix theory (RMT) universality is the defining property of quantum mechanical chaotic systems, and can be probed by observables like the spectral form factor (SFF). In this paper, we describe systematic deviations from RMT behavio…
View article: Quantum Chaos on Edge
Quantum Chaos on Edge Open
In recent years, the physics of many-body quantum chaotic systems close to their ground states has come under intensified scrutiny. Such studies are motivated by the emergence of model systems exhibiting chaotic fluctuations throughout the…
View article: The Influence Functional in open holography: entanglement and Rényi entropies
The Influence Functional in open holography: entanglement and Rényi entropies Open
Open quantum systems are defined as ordinary unitary quantum theories coupled to a set of external degrees of freedom, which are introduced to take on the rôle of an unobserved environment. Here we study examples of open quantum field theo…
View article: Matrix Models for Eigenstate Thermalization
Matrix Models for Eigenstate Thermalization Open
We develop a class of matrix models that implement and formalize the eigenstate thermalization hypothesis (ETH) and point out that, in general, these models must contain non-Gaussian corrections in order to correctly capture thermal mean-f…
View article: Jackiw-Teitelboim gravity with matter, generalized eigenstate thermalization hypothesis, and random matrices
Jackiw-Teitelboim gravity with matter, generalized eigenstate thermalization hypothesis, and random matrices Open
We present evidence for a duality between Jackiw-Teitelboim gravity minimally coupled to a free massive scalar field and a single-trace two-matrix model. One matrix is the Hamiltonian H of a holographic disorder-averaged quantum mechanics,…
View article: A bulk manifestation of Krylov complexity
A bulk manifestation of Krylov complexity Open
A bstract There are various definitions of the concept of complexity in Quantum Field Theory as well as for finite quantum systems. For several of them there are conjectured holographic bulk duals. In this work we establish an entry in the…
View article: Quantum chaos in 2D gravity
Quantum chaos in 2D gravity Open
We present a quantitative and fully non-perturbative description of the ergodic phase of quantum chaos in the setting of two-dimensional gravity. To this end we describe the doubly non-perturbative completion of semiclassical 2D gravity in…
View article: Approximate CFTs and Random Tensor Models
Approximate CFTs and Random Tensor Models Open
A key issue in both the field of quantum chaos and quantum gravity is an effective description of chaotic conformal field theories (CFTs), that is CFTs that have a quantum ergodic limit. We develop a framework incorporating the constraints…
View article: A bulk manifestation of Krylov complexity
A bulk manifestation of Krylov complexity Open
There are various definitions of the concept of complexity in Quantum Field Theory as well as for finite quantum systems. For several of them there are conjectured holographic bulk duals. In this work we establish an entry in the AdS/CFT d…
View article: A cavity quantum electrodynamics implementation of the Sachdev--Ye--Kitaev model
A cavity quantum electrodynamics implementation of the Sachdev--Ye--Kitaev model Open
The search for a quantum theory of gravity has led to the discovery of quantum many-body systems that are dual to gravitational models with quantum properties. The perhaps most famous of these systems is the Sachdev-Ye-Kitaev (SYK) model. …
View article: Generalized spectral form factors and the statistics of heavy operators
Generalized spectral form factors and the statistics of heavy operators Open
View article: Sailing past the End of the World and discovering the Island
Sailing past the End of the World and discovering the Island Open
Large black holes in anti-de Sitter space have positive specific heat and do not evaporate. In order to mimic the behavior of evaporating black holes, one may couple the system to an external bath. In this paper we explore a rich family of…
View article: JT gravity with matter, generalized ETH, and Random Matrices
JT gravity with matter, generalized ETH, and Random Matrices Open
We present evidence for a duality between Jackiw-Teitelboim gravity minimally coupled to a free massive scalar field and a single-trace two-matrix model. One matrix is the Hamiltonian $H$ of a holographic disorder-averaged quantum mechanic…
View article: Matrix models for eigenstate thermalization
Matrix models for eigenstate thermalization Open
We develop a class of matrix models which implement and formalize the `eigenstate thermalization hypothesis' (ETH) and point out that in general these models must contain non-Gaussian corrections, already in order to correctly capture ther…
View article: Report on 2204.07583v2
Report on 2204.07583v2 Open
We present a quantitative and fully non-perturbative description of the ergodic phase of quantum chaos in the setting of two-dimensional gravity.To this end we describe the doubly non-perturbative completion of semiclassical 2D gravity in …
View article: Report on 2204.07583v2
Report on 2204.07583v2 Open
We present a quantitative and fully non-perturbative description of the ergodic phase of quantum chaos in the setting of two-dimensional gravity.To this end we describe the doubly non-perturbative completion of semiclassical 2D gravity in …