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R. Ott, T. Zache, N. Maskara, M. Lukin, P. Zoller, H. Pichler Probing topological entanglement on large scales,
Phys. Rev. Lett. 135 90401 (2025-08-25),
http://dx.doi.org/10.1103/mdsf-wrbj doi:10.1103/mdsf-wrbj (ID: 721272)
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Topologically ordered quantum matter exhibits intriguing long-range patterns of entanglement, which reveal themselves in subsystem entropies. However, measuring such entropies, which can be used to certify topological order, on large partitions is challenging and becomes practically unfeasible for large systems. We propose a protocol based on local adiabatic deformations of the Hamiltonian which extracts the universal features of long-range topological entanglement from measurements on small subsystems of finite size, trading an exponential number of measurements against a polynomial-time evolution. Our protocol is general and readily applicable to various quantum simulation architectures. We apply our method to various string-net models representing both abelian and non-abelian topologically ordered phases, and illustrate its application to neutral atom tweezer arrays with numerical simulations.
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R. Ott, D. González-Cuadra, T. Zache, P. Zoller, A. Kaufman, H. Pichler Error-corrected fermionic quantum processors with neutral atoms,
Phys. Rev. Lett. 135 90601 (2025-08-25),
http://dx.doi.org/10.1103/zkpl-hh28 doi:10.1103/zkpl-hh28 (ID: 721389)
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Many-body fermionic systems can be simulated in a hardware-efficient manner using a fermionic quantum processor. Neutral atoms trapped in optical potentials can realize such processors, where non-local fermionic statistics are guaranteed at the hardware level. Implementing quantum error correction in this setup is however challenging, due to the atom-number superselection present in atomic systems, that is, the impossibility of creating coherent superpositions of different particle numbers. In this work, we overcome this constraint and present a blueprint for an error-corrected fermionic quantum computer that can be implemented using current experimental capabilities. To achieve this, we first consider an ancillary set of fermionic modes and design a fermionic reference, which we then use to construct superpositions of different numbers of referenced fermions. This allows us to build logical fermionic modes that can be error corrected using standard atomic operations. Here, we focus on phase errors, which we expect to be a dominant source of errors in neutral-atom quantum processors. We then construct logical fermionic gates, and show their implementation for the logical particle-number conserving processes relevant for quantum simulation. Finally, our protocol is illustrated using a minimal fermionic circuit, where it leads to a quadratic suppression of the logical error rate.
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H. Froland, T. Zache, R. Ott, N. Müller Entanglement Structure of Non-Gaussian States and How to Measure It,
Phys. Rev. Lett. 135 40201 (2025-07-23),
http://dx.doi.org/10.1103/pnp2-g1g5 doi:10.1103/pnp2-g1g5 (ID: 721640)
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Rapidly growing capabilities of quantum simulators to probe quantum many-body phenomena require new methods to characterize increasingly complex states. We present a protocol that constrains quantum states using experimentally measured correlation functions. This method enables measurement of a quantum state’s entanglement structure, opening a new route to study entanglement-related phenomena. Our approach extends Gaussian state parameterizations by systematically incorporating higher-order correlations. We show the protocol’s usefulness in conjunction with current and forthcoming experimental capabilities, focusing on weakly interacting fermions as a proof of concept. Here, the lowest nontrivial expansion quantitatively predicts early time thermalization dynamics, including signaling the onset of quantum chaos indicated by the entanglement Hamiltonian.