Measurement-induced multipartite-entanglement regimes in collective spin systems

Abstract

We study the competing effects of collective generalized measurements and interaction-induced scrambling in the dynamics of an ensemble of spin-1/2 particles at the level of quantum trajectories. This setup can be considered as analogous to the one leading to measurement-induced transitions in quantum circuits. We show that the interplay between collective unitary dynamics and measurements leads to three regimes of the average Quantum Fisher Information (QFI), which is a witness of multipartite entanglement, as a function of the monitoring strength. While both weak and strong measurements lead to extensive QFI density (i.e., individual quantum trajectories yield states displaying Heisenberg scaling), an intermediate regime of classical-like states emerges for all system sizes where the measurement effectively competes with the scrambling dynamics and precludes the development of quantum correlations, leading to sub-Heisenberg-limited states. We characterize these regimes and the crossovers between them using numerical and analytical tools, and discuss the connections between our findings, entanglement phases in monitored many-body systems, and the quantum-to-classical transition.

16 pages, 7 figures. Typos fixed, section IV. B added in v3 - v4 fixes minor formatting issues. Accepted for publication in Quantum

References in corpus (19)

• Random Quantum Circuits
• Quantum Simulation for High Energy Physics
• Observation of measurement-induced quantum phases in a trapped-ion quantum computer
• Characterizing the entanglement of symmetric many-particle spin-1/2 systems
• Measurement-induced entanglement and teleportation on a noisy quantum processor
• Dissipative Floquet Dynamics: from Steady State to Measurement Induced Criticality in Trapped-ion Chains
• Excited-state quantum phase transitions
• Bridging entanglement dynamics and chaos in semiclassical systems
• Entanglement dynamics in hybrid quantum circuits
• On quantum mean-field models and their quantum annealing
• $N$-body interactions between trapped ion qubits via spin-dependent squeezing
• Collective Spin-Light and Light-Mediated Spin-Spin Interactions in an Optical Cavity
• Purification Timescales in Monitored Fermions
• Dynamical and excited-state quantum phase transitions in collective systems
• Theory of dynamical phase transitions in quantum systems with symmetry-breaking eigenstates
• Phase space geometry and optimal state preparation in quantum metrology with collective spins
• Scrambling and quantum chaos indicators from long-time properties of operator distributions
• Floquet time crystals in driven spin systems with all-to-all $p$-body interactions
• Exponential shortcut to measurement-induced entanglement phase transitions

Cited by in corpus (9)

• Many-body Dynamics in Monitored Atomic Gases Without Post-Selection Barrier
• Interactions and integrability in weakly monitored Hamiltonian systems
• Monitored long-range interacting systems: spin-wave theory for quantum trajectories
• Dynamics of monitored SSH Model in Krylov Space: From Complexity to Quantum Fisher Information
• Entanglement classification and \emph{non-k}-separability certification via Greenberger-Horne-Zeilinger-class fidelity
• Multipartite entanglement structure of monitored quantum circuits
• Dynamical multipartite entanglement in a generalized Tavis-Cummings model with XY spin interaction
• Uncovering measurement-induced entanglement via directional adaptive dynamics and incomplete information
• Fractal structure of multipartite entanglement in monitored quantum circuits