Schwinger-Keldysh field theory for operator Rényi entropy and entanglement growth in non-interacting systems with sub-ballistic transports

• URL: http://arxiv.org/abs/2602.22331v1
• Date: Wed, 25 Feb 2026 19:00:28 GMT
• Title: Schwinger-Keldysh field theory for operator Rényi entropy and entanglement growth in non-interacting systems with sub-ballistic transports
• Authors: Priesh Roy, Sumilan Banerjee,
• Abstract summary: We show that the subsystem operator Rényi entropy encodes both spatial and temporal information.<n>We show that the growth of subsystem operator Rényi entropy and state von Neumann and Rényi entanglement entropies can capture both ballistic and sub-ballistic transport behaviors.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: The notion of operator growth in quantum systems furnishes a bridge between transport and the generation of entanglement between different parts of the system under quantum dynamics. We define a measure of operator growth in terms of subsystem operator Rényi entropy, which provides a state-independent measure of operator growth, unlike entanglement entropies, and the usual measures of operator growth like out-of-time-order correlators. We show that the subsystem operator Rényi entropy encodes both spatial and temporal information, and thus can directly connect to transport for a local operator related to a conserved quantity. We construct a unified Schwinger-Keldysh (SK) field theory formalism for the time evolution of operator Rényi entropy and entanglement entropies of initial pure states. We use the SK field theory to obtain the operator Rényi and state entanglement entropies in terms of infinite-temperature and vacuum Keldysh Green's functions, respectively, for non-interacting systems. We apply the method to explore the connection between operator and entanglement growth, and transport in non-interacting systems with quasiperiodic and random disorder, like the one- and two-dimensional Aubry-André models and the two-dimensional Anderson model. In particular, we show that the growth of subsystem operator Rényi entropy and state von Neumann and Rényi entanglement entropies can capture both ballistic and sub-ballistic transport behaviors, like diffusive and anomalous diffusive transport, as well as localization in these systems.

Related papers

• Topological Boundary Time Crystal Oscillations [39.146761527401424]
  Boundary time crystals (BTCs) break time-translation symmetry and exhibit long-lived, robust oscillations insensitive to initial conditions.<n>We show that collective spin BTCs can admit emergent topological winding numbers in operator space.<n>Our results frame BTC dynamics as a form of topologically constrained operator space transport.
  arXiv  Detail & Related papers  (2026-02-19T19:00:17Z)
• Operator delocalization in disordered spin chains via exact MPO marginals [0.0]
  We introduce a complementary measure of operator complexity: the operator length.<n>Both quantities are defined from the expansion of time-evolved operators in the Pauli basis.<n>We show that both the operator mass and length can be computed efficiently and exactly within a matrix-productoperator framework.
  arXiv  Detail & Related papers  (2026-01-18T15:03:25Z)
• Observation of non-Hermitian topology in cold Rydberg quantum gases [42.41909362660157]
  We experimentally demonstrate non-Hermitian spectra topology in a dissipative Rydberg atomic gas.<n>By increasing the interaction strength, the system evolves from Hermitian to non-Hermitian regime.<n>This work establishes cold Rydberg gases as a versatile platform for exploring the rich interplay between non-Hermitian topology, strong interactions, and dissipative quantum dynamics.
  arXiv  Detail & Related papers  (2025-09-30T13:44:43Z)
• Free mutual information and higher-point OTOCs [0.0]
  We introduce a quantity called the free mutual information (FMI) as a new physical measure of quantum chaos.<n>We identify universal behaviours of the FMI and higher-point out-of-time-ordered correlators across a variety of chaotic systems.
  arXiv  Detail & Related papers  (2025-09-16T18:00:01Z)
• Entanglement transitions in a boundary-driven open quantum many-body system [0.0]
  We introduce a numerical framework for integrating Markovian dynamics on tree tensor operator (TTO) ansatz states.<n>We demonstrate its capability to probe entanglement in open quantum many-body systems.
  arXiv  Detail & Related papers  (2025-02-25T17:09:13Z)
• Anomalous transport in U(1)-symmetric quantum circuits [41.94295877935867]
  Investigation of discrete-time transport in a generic U(1)-symmetric disordered model tuned across an array of different dynamical regimes. We develop an aggregate quantity, a circular statistical moment, which is a simple function of the magnetization profile. From this quantity we extract transport exponents, revealing behaviors across the phase diagram consistent with localized, diffusive, and - most interestingly for a disordered system - superdiffusive regimes.
  arXiv  Detail & Related papers  (2024-11-21T17:56:26Z)
• Operator Space Entangling Power of Quantum Dynamics and Local Operator Entanglement Growth in Dual-Unitary Circuits [0.0]
  We introduce a measure for the ability of a unitary channel to generate operator entanglement, representing an operator-level generalization of the state-space entangling power. For dual-unitary circuits, a combination of analytical and numerical investigations demonstrates that the average growth of local operator entanglement exhibits two distinct regimes.
  arXiv  Detail & Related papers  (2024-06-14T17:40:53Z)
• Environment-Induced Information Scrambling Transition with Charge Conservations [6.659260341668616]
  In generic closed quantum systems, the complexity of operators increases under time evolution governed by the Heisenberg equation. When systems interact with an external environment, the system-environment coupling allows operators to escape from the system. This transition is known as the environment-induced information scrambling transition, originally proposed in Majorana fermion systems.
  arXiv  Detail & Related papers  (2024-03-13T15:36:53Z)
• Engineering Transport via Collisional Noise: a Toolbox for Biology Systems [44.99833362998488]
  We study a generalised XXZ model in the presence of collision noise, which allows to describe environments beyond the standard Markovian formulation. Results constitute an example of the essential building blocks for the understanding of quantum transport in noisy and warm disordered environments.
  arXiv  Detail & Related papers  (2023-11-15T12:55:28Z)
• Information Scrambling in Free Fermion Systems with a Sole Interaction [7.11602492803827]
  We construct Brownian circuits and Clifford circuits consisting of a free fermion hopping term and a sole interaction. In both circuits, our findings reveal the emergence of operator scrambling. We demonstrate that in the one-dimensional system, both the operator and entanglement exhibit diffusive scaling.
  arXiv  Detail & Related papers  (2023-10-10T22:11:38Z)
• Independent Natural Policy Gradient Methods for Potential Games: Finite-time Global Convergence with Entropy Regularization [28.401280095467015]
  We study the finite-time convergence of independent entropy-regularized natural policy gradient (NPG) methods for potential games. We show that the proposed method converges to the quantal response equilibrium (QRE) at a sublinear rate, which is independent of the size of the action space.
  arXiv  Detail & Related papers  (2022-04-12T01:34:02Z)
• Neural-Network Quantum States for Periodic Systems in Continuous Space [66.03977113919439]
  We introduce a family of neural quantum states for the simulation of strongly interacting systems in the presence of periodicity. For one-dimensional systems we find very precise estimations of the ground-state energies and the radial distribution functions of the particles. In two dimensions we obtain good estimations of the ground-state energies, comparable to results obtained from more conventional methods.
  arXiv  Detail & Related papers  (2021-12-22T15:27:30Z)
• Probing Operator Spreading via Floquet Engineering in a Superconducting Circuit [18.17297057914507]
  Floquet engineering provides an effective way to tune the coupling strength between nearby qubits. A clear light-cone-like operator propagation is observed in the system with multiple excitations. For the butterfly operator that is nonlocal (local) under the Jordan-Wigner transformation, the OTOCs show distinct behaviors.
  arXiv  Detail & Related papers  (2021-08-03T03:46:23Z)
• Out-of-time-order correlations and the fine structure of eigenstate thermalisation [58.720142291102135]
  Out-of-time-orderors (OTOCs) have become established as a tool to characterise quantum information dynamics and thermalisation. We show explicitly that the OTOC is indeed a precise tool to explore the fine details of the Eigenstate Thermalisation Hypothesis (ETH) We provide an estimation of the finite-size scaling of $omega_textrmGOE$ for the general class of observables composed of sums of local operators in the infinite-temperature regime.
  arXiv  Detail & Related papers  (2021-03-01T17:51:46Z)
• Relevant OTOC operators: footprints of the classical dynamics [68.8204255655161]
  The OTOC-RE theorem relates the OTOCs summed over a complete base of operators to the second Renyi entropy. We show that the sum over a small set of relevant operators, is enough in order to obtain a very good approximation for the entropy. In turn, this provides with an alternative natural indicator of complexity, i.e. the scaling of the number of relevant operators with time.
  arXiv  Detail & Related papers  (2020-07-31T19:23:26Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.