Stability of macroscopic quantum states

明 清水

Florian Fröwis, Wolfgang Dür

We study the stability of superpositions of macroscopically distinct quantum states under decoherence. We introduce a class of quantum states with entanglement features similar to Greenberger-Horne-Zeilinger (GHZ) states, but with an inherent stability against noise and decoherence. We show that in contrast to GHZ states, these so-called concatenated GHZ states remain multipartite entangled even for macroscopic numbers of particles and can be used for quantum metrology in noisy environments. We also propose a scalable experimental realization of these states using existing ion-trap setups.

Christopher Mudry, Eduardo Fradkin

We study a class of infinite-range spin-(1/2 quantum Heisenberg antiferromagnets. We show that, in addition to ground states with macroscopic net spin in one or several sublattices (``N\'eel states''), there are valence-bond (VB) states that are local spin singlets. We show that there is a class of perturbations that stabilizes the VB state. We characterize the excitation spectrum and find an order parameter for the VB states. Finally, we extend our method to find perturbations that stabilize microscopic as well as macroscopic chiral states.

Andreas Pernt

This preprint formulates Schrödinger’s cat as a boundary case of macroscopic residual-cluster stabilization within the Asymmetric Source Field Model (ASFM). Instead of treating the cat as a fundamental object placed into competing macroscopic states, the manuscript describes macroscopic reality as stabilized wave-field topology.The ASFM framework starts from the residual field relationwhere constructive source-field components and destructive compensation-field components generate finite, nonzero residual interference structures. Residual nodes are treated as real-space coherence structures, while the quotient structure provides the algebraic stabilization framework.The manuscript distinguishes residual nodes, cluster classes, quotient mappings, causal-retarded field action, topological correlation, and non-claimed simultaneous marginal control. Measurement is described as residual-cluster stabilization rather than as the collapse of a fundamental macroscopic object. The work also states explicit failure conditions and open validation points for future ASFM measurement dynamics.