Quantum chaos, scrambling and operator growth in $$ T\overline{T} $$ deformed SYK models

We study the operator growth in open quantum systems with dephasing dissipation terms, extending the Krylov complexity formalism of [1]. Our results are based on the study of the dissipative q-body Sachdev-Ye-Kitaev (SYKq) model, governed by the Markovian dynamics. We introduce a notion of “operator size concentration” which allows a diagrammatic and combinatorial proof of the asymptotic linear behavior of the two sets of Lanczos coefficients (an and bn) in the large q limit. Our results corroborate with the semi-analytics in finite q in the large N limit, and the numerical Arnoldi iteration in finite q and finite N limit. As a result, Krylov complexity exhibits exponential growth following a saturation at a time that grows logarithmically with the inverse dissipation strength. The growth of complexity is suppressed compared to the closed system results, yet it upper bounds the growth of the normalized out-of-time-ordered correlator (OTOC). We provide a plausible explanation of the results from the dual gravitational side.

Section: Introductionmentioning

confidence: 99%

Operator growth in open quantum systems: lessons from the dissipative SYK

Bhattacharjee

Cao

Nandy

et al. 2023

“…Another interesting direction is to investigate the fate of quantum chaos in theories which are deformed by the (0 + 1)-dimensional version of root-T T . A similar analysis for the quantum mechanical analogue of T T was carried out in [40], focusing on the spectral form factor, out-of-time-order correlator, and Krylov complexity. There it was found that, in a certain sense, the chaotic behavior of SYK-like models remains unchanged by the (0 + 1)dimensional version of T T , and the effect of the deformation is essentially a rescaling of the time parameter.…”

Section: Chaos and Deformations Of Sykmentioning

confidence: 99%

“…Although these Hamiltonian flows are in some sense simple, one can already observe interesting phenomena in the resulting deformed theories. For instance, one can study signatures of chaos in f (H) deformed versions of SYK models [40], and flows of this type have appeared in the study of deformed string worldsheets in pp wave backgrounds [41]; the latter are connected to T T -like deformations of spin chains, which have also been analyzed in [42,43].…”

Section: Bosonic Flowsmentioning

confidence: 99%

Non-linear supersymmetry and $$ T\overline{T} $$-like flows

Ferko

Jiang

Sethi

et al. 2020

The TT deformation of a supersymmetric two-dimensional theory preserves the original supersymmetry. Moreover, in several interesting cases the deformed theory possesses additional non-linearly realized supersymmetries. We show this for certain N = (2, 2) models in two dimensions, where we observe an intriguing similarity with known N = 1 models in four dimensions. This suggests that higher-dimensional models with non-linearly realized supersymmetries might also be obtained from TT -like flow equations.We show that in four dimensions this is indeed the case for N = 1 Born-Infeld theory, as well as for the Goldstino action for spontaneously broken N = 1 supersymmetry. arXiv:1910.01599v1 [hep-th] 3 Oct 2019Contents 1 Introduction 1 2 D = 2 N = (2, 2) Flows and Non-Linear N = (2, 2) Supersymmetry 4 2.1 TT deformations with N = (2, 2) supersymmetry 4 2.2 The TT -deformed twisted-chiral model and partial-breaking 7 2.3 The TT -deformed chiral model and partial-breaking 13 3 D = 4 T 2 Deformations and Their Supersymmetric Extensions 16 3.1 Comments on the T 2 operator in D = 4 16 3.2 D = 4 N = 1 supercurrent-squared operator 18 4 Bosonic Born-Infeld As a T 2 Flow 20 5 Supersymmetric Born-Infeld From Supercurrent-Squared Deformation 22 7 Conclusions and Outlook 33 A Deriving a Useful On-shell Identity 36 construct two models describing the partial supersymmetry breaking pattern N = (4, 4) → N = (2, 2) in D = 2. These models have manifest N = (2, 2) supersymmetry from the superspace structure used in their construction, but they also admit another hidden nonlinear N = (2, 2) supersymmetry. It turns out the resulting actions are exactly the same as the N = (2, 2) chiral and twisted chiral TT -deformed actions of [18]. The intriguing relation between non-linear supersymmetry and TT therefore persists for models with manifest N = (2, 2) supersymmetry. Interestingly, even the D = 2 Volkov-Akulov action, describing the dynamics of the Goldstinos which arise from the spontaneous breaking of N = (2, 2) supersymmetry, satisfies a TT flow equation [21]. This collection of examples motivates us to see whether any higher-dimensional theories with non-linear supersymmetries might also satisfy TT -like flow equations. It has been known for more than two decades that the Bagger-Galperin action for the D = 4 N = 1 Born-Infeld theory describes N = 2 → N = 1 partial supersymmetry breaking [22]. Does the Bagger-Galperin action arise from a TT -like deformation of N = 1 Maxwell theory? That the linear order deformation is given by a supercurrent-squared operator was noted long ago in [23]. Much more recently, bosonic Born-Infeld theory was shown to satisfy a T 2 flow equation, where T 2 is an operator quadratic in the stress-energy tensor [24]. In this work, we explicitly show that the Bagger-Galperin action indeed satisfies a supercurrentsquared flow equation, generalizing the observation of [23] to all orders in the deformation parameter. The supercurrent-squared deformation operator is constructed from supercurrent multiplets, but its to...

“…This correspondence does not exist in canonical nonlinear dynamics, and builds up a deep connection between novel chaotic phenomena and black hole physics. On the other hand, the SYK model allows nice embedding of various SUSY(-like) structures, whose consequences are currently under investigations [1,20,21,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. So it is natural to ask whether and how these structures influence system's chaotic behaviors.…”

Section: Jhep01(2024)196mentioning

confidence: 99%

A string-theoretical analog of non-maximal chaos in some Sachdev-Ye-Kitaev-like models

Tian,

Ma,

Chen

2024

Very recently two of the present authors have studied the chaos exponent of some Sachdev-Ye-Kitaev (SYK)-like models for arbitrary interaction strength [1]. These models carry supersymmetric (SUSY) or SUSY-like structures. Namely, bosons and Majorana fermions are both present and each of them interacts with (q − 1) particles, but the model is not necessarily supersymmetric. It was found that the chaos exponents in different models, no matter whether they carry SUSY(-like) structures or not, all follow a universal single-parameter scaling law for large q, and by tuning that parameter continuously a flow from maximally chaotic to completely regular motion results. Here we report a string-theoretical analog of this chaotic phenomenon. Specifically, we consider closed string scattering near the two-sided AdS black hole, whose amplitude grows exponentially in the Schwarzschild time, with a rate determined by the Regge spin of the Pomeron exchanged during string scattering. We calculate the Pomeron Regge spin for strings of different types, including the bosonic string, the type II superstring and the heterotic superstring. We find that the Pomeron Regge spin also displays a single-parameter scaling behavior independent of string types, with the parameter depending on the string length and the length scale characterizing the spacetime curvature; moreover, the scaling function has the same limiting behaviors as that for the chaos exponent of SYK-like models. Remarkably, the flow from maximally chaotic to completely regular motion in SYK-like models corresponds to the flow of the Pomeron Regge spin from 2 to 1.