Information Transport Achieves Scale-Resolved Entanglement in Open Fermion Chains

Scientists are increasingly focused on understanding entanglement dynamics in open quantum systems under steady-state transport conditions! Andrea Nava, Claudia Artiaco, and et al. from institutions including the Heinrich-Heine-Universität Düsseldorf and KTH Royal Institute of Technology, present a novel approach utilising ‘information’ as a key quantity to circumvent challenges posed by entanglement’s nonlocality, a significant hurdle in establishing hydrodynamic equations! Their research, employing the innovative “information lattice” framework and Lindblad master equations applied to noninteracting fermion chains, demonstrates that information currents are experimentally accessible through noise and particle measurements! Crucially, this work reveals how impurities and particle-hole asymmetry induce information flow and entanglement, paving the way for systematic investigations into information transport and entanglement generation in driven, open quantum systems far from equilibrium.

Information. The study harnessed Lindblad master equations to model these systems, allowing for detailed analysis of information flow and entanglement generation. Experiments were designed around a 1D fermionic chain governed by a short-range quadratic Hamiltonian, coupled to external environments via local Lindblad jump operators! These operators, linear in the fermionic operators, simulated particle injection and removal, establishing non-equilibrium steady states carrying finite current. Crucially, the team leveraged the fact that Gaussian states remain Gaussian under Lindbladian time evolution, simplifying the characterisation of information transport and enabling calculations for large system sizes.

The full many-body density matrix was determined by the two-body correlation matrix, whose dynamics obeyed a closed set of equations of motion, streamlining the analysis. To quantify bipartite entanglement, scientists utilised the fermionic negativity, correlating it with the observed information currents! For a clean, particle-hole symmetric chain, the research revealed that information currents were shielded from entering the information lattice, a surprising result indicating a fundamental constraint on information flow. Introducing impurities or particle-hole asymmetry broke this shielding, inducing information current flow and entanglement between the chain’s end segments, a key finding demonstrating the role of system imperfections in enabling long-range quantum correlations.

This work pioneered a method to experimentally access local information via a “noise lattice”, quantifying local particle number fluctuations! Local information currents were determined by measuring particle currents, onsite occupations, and covariances of particle numbers, offering a direct pathway for experimental verification using platforms like quantum dot arrays or ultracold fermionic atoms. The approach enables the measurement of information flow patterns without requiring full quantum state tomography, representing a significant methodological advance and opening doors for systematic investigations of information transport in driven, open quantum systems far from equilibrium.

Information shielding in particle-hole symmetric fermionic chains is

Scientists have demonstrated a novel method for characterizing information currents in open fermionic systems, revealing insights into entanglement dynamics under steady-state transport conditions! The research, employing the recently developed “information lattice” framework, successfully links information flow to experimentally accessible quantities like noise measurements and particle currents. Specifically, the team utilized Lindblad master equations to model noninteracting fermion chains coupled to dissipative reservoirs, establishing a crucial connection between information and particle-number fluctuations. Experiments revealed that for a clean, particle-hole symmetric chain, information currents are effectively shielded from propagating within the information lattice.

This “shielding effect” is broken by the introduction of impurities or particle-hole asymmetry, subsequently enabling information current flow and inducing entanglement between the chain’s end segments. Measurements confirm that local information currents can be determined by evaluating the time derivative of the noise lattice, accessing particle currents, onsite occupation numbers, and covariances of particle numbers and/or particle currents. The breakthrough delivers a pathway to probe local information through a “noise lattice” quantifying local particle number fluctuations, offering a direct experimental route without requiring quantum state tomography. Data shows that the presence of defects in the system generates long-range quantum correlations, manifesting as information currents extending across the system size in nonequilibrium steady states.

These correlations are absent at equilibrium, highlighting the role of transport conditions in inducing entanglement. Researchers recorded that particle-hole asymmetry leads to asymmetric information current patterns, further demonstrating the system’s sensitivity to external parameters. The team successfully quantified the shielding effect, observing that information currents injected from the environment are prohibited from entering the bulk of the information lattice in the clean, particle-hole symmetric case. Tests prove that the fermionic negativity, used to quantify bipartite entanglement, correlates directly with the observed information currents, providing a consistent picture of transport-induced entanglement. The study establishes that local information currents are fully determined by the correlation matrix, allowing for experimental access via interferometric approaches applicable to platforms like quantum dot arrays or ultracold fermionic atoms. This work opens the door to systematic investigations of information transport and entanglement generation in driven open systems far from equilibrium, promising controlled studies of many-body quantum systems.

Noise reveals accessible quantum information flow in many-body

Scientists have developed a new framework to investigate information and entanglement transport in open quantum systems! Researchers characterised spatially and scale-resolved information currents within non-interacting fermion chains coupled to dissipative reservoirs, utilising a recently developed “information lattice” approach. By linking this lattice to a noise lattice, constructed from particle-number fluctuations, they demonstrated that information is experimentally accessible through noise measurements! The study reveals that information currents are typically shielded within a particle-hole symmetric chain, but this shielding breaks down with impurities or asymmetry, leading to information flow and entanglement between chain segments.

Specifically, local information currents can be determined by measuring particle currents, site occupations, and covariances of particle numbers and/or currents. Using the fermionic negativity, the team also examined transport-induced entanglement and its connection to these information currents! The authors acknowledge a limitation in focusing on non-interacting fermion chains, which simplifies the analysis but may not fully capture the complexity of interacting systems. Future research could extend this framework to investigate driven open systems further from equilibrium and explore the impact of interactions on information and entanglement transport.

These findings are significant because they offer a pathway to systematically study information transport and entanglement generation in complex quantum systems, potentially aiding the development of quantum technologies. The ability to relate information currents to experimentally measurable quantities, like noise and particle currents, represents a crucial step towards probing quantum phenomena in real-world devices. This work establishes a connection between information and entanglement, offering a novel perspective on understanding the dynamics of open quantum systems.