- Open Access
Fractional Quantum Hall States under Density Decoherence
Phys. Rev. X 16, 031074 – Published 21 September, 2026
DOI: https://doi.org/10.1103/bw7c-y5dc
Abstract
Fractional quantum Hall states are promising platforms for topological quantum computation due to their capacity to encode quantum information in topologically degenerate ground states and in the fusion space of non-Abelian anyons. We investigate how the information encoded in two paradigmatic states, the Laughlin and Moore-Read states, is affected by density decoherence—coupling of local charge density to nonthermal noise. We identify a critical filling factor , above which the quantum information remains fully recoverable for arbitrarily strong decoherence. The Laughlin state and Moore-Read state both lie within this range. Below both classes of states undergo a decoherence-induced Berezinskii-Kosterlitz-Thouless (BKT) transition into a critical decohered phase. For Laughlin states, information encoded in the topological ground state manifold degrades continuously with decoherence strength inside this critical phase, vanishing only in the limit of infinite decoherence strength. On the other hand, quantum information encoded in the fusion space of non-Abelian anyons of the Moore-Read states remains fully recoverable under arbitrarily strong decoherence even beyond the BKT transition. These results lend further support to the promise of non-Abelian FQH states as platforms for topological quantum computation. They reveal how the interplay between chiral topological order and global symmetry can give rise to novel mixed-state phases under decoherence, distinguished by their capacity for storing quantum information.
Physics Subject Headings (PhySH)
Popular Summary
How does quantum information stored in fractional quantum Hall states evolve under noise? Thermal noise is effectively suppressed by cooling below the energy gap, but decoherence from external nonequilibrium sources can still affect the sample at low temperatures. We study the effect of such decoherence, coupled to the local charge density using mappings to statistical mechanics models. In Laughlin states, we find a critical filling factor above which the quantum information stored in the topological ground state degeneracy remains stable to arbitrary strong charge decoherence. For smaller filling factors, we identify a threshold at a finite decoherence strength, above which the encoded information gradually degrades. Moore-Read states, on the other hand, can store quantum information in exotic (non-Abelian) excitations and we find that this information is resilient to arbitrary strength of charge noise regardless of filling factor. These results lay the groundwork for future error correction in quantum Hall devices.
Article Text
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