Entanglement and decoherence in many-body physics

Quantum Monte Carlo (QMC) methods are among the central numerical tools for studying strongly correlated quantum many-body systems, particularly in higher dimensions. As quantum information has introduced new information-theoretic perspectives and diagnostics into many-body physics, QMC methods have accordingly been extended beyond the measurement of conventional linear observables. This review summarizes recent progress in adapting QMC to many-body quantum-information, focusing on qubit or spin- $1/2$ systems as a concrete setting while keeping the discussion broadly applicable to qudit and bosonic systems. We present a unified perspective on the extraction of nonlinear diagnostics, including entanglement entropies and entanglement spectra, Rényi negativities for mixed-state entanglement, stabilizer entropies for quantum magic, and decoherence-driven phenomena such as the interplay between imaginary-time evolution and decoherence and strong-to-weak spontaneous symmetry breaking.Quantum Monte Carlo (QMC) methods are among the central numerical tools for studying strongly correlated quantum many-body systems, particularly in higher dimensions. As quantum information has introduced new information-theoretic perspectives and diagnostics into many-body physics, QMC methods have accordingly been extended beyond the measurement of conventional linear observables. This review summarizes recent progress in adapting QMC to many-body quantum-information, focusing on qubit or spin-$1/2$ systems as a concrete setting while keeping the discussion broadly applicable to qudit and bosonic systems. We present a unified perspective on the extraction of nonlinear diagnostics, including entanglement entropies and entanglement spectra, Rényi negativities for mixed-state entanglement, stabilizer entropies for quantum magic, and decoherence-driven phenomena such as the interplay between imaginary-time evolution and decoherence and strong-to-weak spontaneous symmetry breaking.

quant-pharXiv:2608.23231Aug 25, 20260 citations

Many-body protected entanglement generation in interacting spin systems

Ana María Rey, Liang Jiang, Michael Fleischhauer +2 more

We discuss a method to achieve decoherence resistant entanglement generation in strongly interacting ensembles of two-level spin systems. Our method uses designed gapped Hamiltonians to create a protected manifold of multidegenerate levels which is robust against local decoherence processes. We apply the protected evolution to achieve decoherence resistant generation of many-particle Greenberger-Horne-Zeilinger (GHZ) states in two specific physical systems, trapped ions and neutral atoms in optical lattices, and discuss how to engineer the desired many-body protected manifold with them. We analyze the fidelity of GHZ generation and show our method can significantly increase the sensitivity in frequency spectroscopy.We discuss a method to achieve decoherence resistant entanglement generation in strongly interacting ensembles of two-level spin systems. Our method uses designed gapped Hamiltonians to create a protected manifold of multidegenerate levels which is robust against local decoherence processes. We apply the protected evolution to achieve decoherence resistant generation of many-particle Greenberger-Horne-Zeilinger (GHZ) states in two specific physical systems, trapped ions and neutral atoms in optical lattices, and discuss how to engineer the desired many-body protected manifold with them. We analyze the fidelity of GHZ generation and show our method can significantly increase the sensitivity in frequency spectroscopy.

arXiv:0706.3378Physical Review AMay 5, 200856 citations

Aspects of Entanglement in Quantum Many-Body Systems

J. W. Clark, Hessam Habibian, Aikaterini Mandilara +1 more

Foundations of PhysicsJun 9, 20104 citations

Decoherence and loss of entanglement

Vladimir Privman A, Denis Tolkunov

We review our recent work establishing by an explicit many-body calculation for an open quantum-mechanical system of two qubits subject to independent noise modelled by bosonic baths, a newly identified connection between two important quantities in the studies of entanglement and decoherence. We demonstrate that the decay of entanglement is governed by the product of the suppression factors describing decoherence of the subsystems (qubits). This result is a detailed model calculation proving an important and intuitively natural physical property that separated open quantum systems can evolve coherently, quantum mechanically on time scales larger than the times for which they remain entangled. Our result also suggests avenues for future work. Specifically, for multiqubit systems, it is expected that similar arguments should apply "by induction." This will stimulate research to develop appropriate quantitative measures of entanglement, and attempts to quantify entanglement and decoherence in a unified way. We considered one "physically meaningful" measure of two-qubit entanglement, the concurrence. In future research, it would be of interest to obtain similar results for other measures of entanglement as well.We review our recent work establishing by an explicit many-body calculation for an open quantum-mechanical system of two qubits subject to independent noise modelled by bosonic baths, a newly identified connection between two important quantities in the studies of entanglement and decoherence. We demonstrate that the decay of entanglement is governed by the product of the suppression factors describing decoherence of the subsystems (qubits). This result is a detailed model calculation proving an important and intuitively natural physical property that separated open quantum systems can evolve coherently, quantum mechanically on time scales larger than the times for which they remain entangled. Our result also suggests avenues for future work. Specifically, for multiqubit systems, it is expected that similar arguments should apply "by induction." This will stimulate research to develop appropriate quantitative measures of entanglement, and attempts to quantify entanglement and decoherence in a unified way. We considered one "physically meaningful" measure of two-qubit entanglement, the concurrence. In future research, it would be of interest to obtain similar results for other measures of entanglement as well.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEMay 25, 20055 citations

1/2

systems as a concrete setting while keeping the discussion broadly applicable to qudit and bosonic systems. We present a unified perspective on the extraction of nonlinear diagnostics, including entanglement entropies and entanglement spectra, Rényi negativities for mixed-state entanglement, stabilizer entropies for quantum magic, and decoherence-driven phenomena such as the interplay between imaginary-time evolution and decoherence and strong-to-weak spontaneous symmetry breaking.