Fast-Scrambling and Operator Confinement Using an Auxiliary Qubit

• URL: http://arxiv.org/abs/2301.02091v1
• Date: Thu, 5 Jan 2023 14:52:28 GMT
• Title: Fast-Scrambling and Operator Confinement Using an Auxiliary Qubit
• Abstract summary: We study a fast-to-slow scrambling transition mediated by an auxiliary central qubit (c-qubit) We find a surprising transition from super-ballistic scrambling and information growth to continuously restricted sub-ballistic entanglement and operator growth.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: We introduce a minimal model for realizing a fast-to-slow scrambling transition mediated by an auxiliary central qubit (c-qubit). The c-qubit is coupled to a spin-$1/2$ Ising model with local Ising interactions and tunable c-qubit-spin coupling. Each spin becomes next-nearest neighbor to all others through the c-qubit, which mediates effective all-to-all interactions. As the interaction with the c-spin increases, we find a surprising transition from super-ballistic scrambling and information growth to continuously restricted sub-ballistic entanglement and operator growth. This slow growth occurs on intermediate timescales that extend exponentially with increasing coupling and system size, indicative of logarithmic entanglement growth. We find that in the slow-scrambling regime, the c-qubit Ising interaction allows commuting operators to grow support on all sites rapidly, while operators orthogonal to the interaction become echoed out. This projects local operators to lie in a restricted subspace and prevents extensive operator entanglement growth. We provide exact dynamics of small systems working with non-equilibrium, effective infinite temperature states, and additionally contribute analytic early-time expansions that support the observed rapid scrambling to quantum Zeno-like crossover. Tracing out the central qubit provides a unique translation from the full, closed unitary dynamics to a simple open system construction consisting of a typical spin-chain with hidden qubit degree of freedom.

Related papers

• Crossover from Fast Scrambling to Operator Confinement Tuned by an Auxiliary Qubit [0.0]
  We show a disorder-free spin chain Hamiltonian which realizes a crossover between super-ballistic, ancilla-accelerated scrambling and sub-ballistic operator confinement.<n>Our minimal model is the mixed-field Ising chain with a spin-1/2 ancilla coupled to its longitudinal magnetization.
  arXiv  Detail & Related papers  (2026-08-17T15:01:20Z)
• Topological Control of Quantum Chaos Diagnostics: OTOCs, Spectral Statistics, and Information Scrambling in Ising Model [0.0]
  We investigate the integrability-to-chaos transition and information scrambling in Ising spin networks.<n>Long-range couplings and heterogeneous degree distributions drastically accelerate quantum information propagation.<n>This work establishes a unified framework bridging network topology with information-theoretic, operator, and spectral diagnostics.
  arXiv  Detail & Related papers  (2026-07-02T17:29:35Z)
• Logarithmic growth of operator entanglement in a clean non-integrable circuit [0.0]
  We study intermediate and long-time dynamics of a system in a finite, large volume.<n>Despite the model being non-integrable and free from any quenched disorder, the operator entanglement grows at most logarithmic in time.<n>The operator size distribution also becomes bimodal at certain times, displaying intermediate behavior between chaotic and free systems.
  arXiv  Detail & Related papers  (2026-03-19T18:01:34Z)
• 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)
• Diffusion Forcing for Multi-Agent Interaction Sequence Modeling [52.769202433667125]
  MAGNet is a unified autoregressive diffusion framework for multi-agent motion generation.<n>It supports a wide range of interaction tasks through flexible conditioning and sampling.<n>It captures both tightly synchronized activities and loosely structured social interactions.
  arXiv  Detail & Related papers  (2025-12-19T18:59:02Z)
• Quantum channel for modeling spin-motion dephasing in Rydberg chains [44.99833362998488]
  We introduce a quantum channel to model the dissipative dynamics resulting from the coupling between spin and motional degrees of freedom in chains of neutral atoms with Rydberg interactions.<n>We benchmark the accuracy of our approach against exact diagonalization for small systems, identifying its regime of validity and the onset of perturbative breakdown.<n>We then apply the quantum channel to compute fidelity loss during transport of single-spin excitations across extended Rydberg chains in intractable regimes via exact diagonalization.
  arXiv  Detail & Related papers  (2025-06-30T17:37:38Z)
• Decoherence and fidelity enhancement during shuttling of entangled spin qubits [45.05458154702236]
  We show that noises acting on the shuttled spins exhibit complex and unusual correlations.<n>These correlations can also be exploited to enhance the shuttling fidelity.<n>We show that by encoding logical qubit in a state of two consequtively shuttled entangled spins, high fidelity can be achieved even for very slow shuttling.
  arXiv  Detail & Related papers  (2025-06-24T14:37:39Z)
• Information scrambling and entanglement dynamics in Floquet Time Crystals [49.1574468325115]
  We study the dynamics of out-of-time-ordered correlators (OTOCs) and entanglement of entropy as measures of information propagation in disordered systems.
  arXiv  Detail & Related papers  (2024-11-20T17:18:42Z)
• 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)
• Scaling Large Language Model-based Multi-Agent Collaboration [72.8998796426346]
  Recent breakthroughs in large language model-driven autonomous agents have revealed that multi-agent collaboration often surpasses each individual through collective reasoning. This study explores whether the continuous addition of collaborative agents can yield similar benefits.
  arXiv  Detail & Related papers  (2024-06-11T11:02:04Z)
• KPZ scaling from the Krylov space [83.88591755871734]
  Recently, a superdiffusion exhibiting the Kardar-Parisi-Zhang scaling in late-time correlators and autocorrelators has been reported. Inspired by these results, we explore the KPZ scaling in correlation functions using their realization in the Krylov operator basis.
  arXiv  Detail & Related papers  (2024-06-04T20:57:59Z)
• Exact dynamics of quantum dissipative $XX$ models: Wannier-Stark localization in the fragmented operator space [49.1574468325115]
  We find an exceptional point at a critical dissipation strength that separates oscillating and non-oscillating decay. We also describe a different type of dissipation that leads to a single decay mode in the whole operator subspace.
  arXiv  Detail & Related papers  (2024-05-27T16:11:39Z)
• Two-qubit logic between distant spins in silicon [0.5561396798949833]
  In this work, we utilize a superconducting resonator to facilitate a coherent interaction between two semiconductor spin qubits 250 $mu$m apart. Results hold promise for scalable networks of spin qubit modules on a chip.
  arXiv  Detail & Related papers  (2023-10-25T17:37:03Z)
• 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)
• Leveraging Low-Rank and Sparse Recurrent Connectivity for Robust Closed-Loop Control [63.310780486820796]
  We show how a parameterization of recurrent connectivity influences robustness in closed-loop settings. We find that closed-form continuous-time neural networks (CfCs) with fewer parameters can outperform their full-rank, fully-connected counterparts.
  arXiv  Detail & Related papers  (2023-10-05T21:44:18Z)
• Qubit readouts enabled by qubit cloaking [49.1574468325115]
  Time-dependent drives play a crucial role in quantum computing efforts. They enable single-qubit control, entangling logical operations, as well as qubit readout. Qubit cloaking was introduced in Lled'o, Dassonneville, et al.
  arXiv  Detail & Related papers  (2023-05-01T15:58:25Z)
• Unveiling operator growth in SYK quench dynamics [4.176752121302988]
  We study non-equilibrium dynamics induced by a sudden quench of strongly correlated Hamiltonians with all-to-all interactions. By tracking the time-evolution of specific spin-spin correlation functions and their decay, we argue that it is possible to distinguish between operator hopping and operator growth dynamics.
  arXiv  Detail & Related papers  (2020-07-07T15:27:16Z)
• Minimal Model for Fast Scrambling [0.0]
  We study quantum information scrambling in spin models with both long-range all-to-all and short-range interactions. We argue that a simple global, spatially homogeneous interaction together with local chaotic dynamics is sufficient to give rise to fast scrambling.
  arXiv  Detail & Related papers  (2020-05-11T18:11:57Z)
• Long-range interaction in an open boundary-driven Heisenberg spin lattice: A far-from-equilibrium transition to ballistic transport [62.997667081978825]
  We study an open Heisenberg XXZ spin chain with long-range Ising-type interaction. We find that the chain lengths for this transition are increasing with decreasing range of the Ising-type interactions between distant spins. The transition can be explained by the suppression of ferromagnetic domains at the edges of the chain.
  arXiv  Detail & Related papers  (2020-04-27T12:22:50Z)

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.