In quantum physics it is commonplace to model the interaction of remote systems with a many-body Hamiltonian. Taking such an action-at-a-distance description {\it \`a la lettre} leads to various paradoxes related to faster-than-light communication and apparent inconsistencies in local energy accounting. It also neglects residual effects, such as entanglement between the remote systems and the mediator that implements the interaction, or the decoherence that arises when the remote systems undergo local evolution. We study simple microscopic quantum models that respect the light cone by design and reproduce two-body Hamiltonians. For these models we quantitatively analyze the residual effects of the microscopic mediator on the remote systems, including dressing of stationary states, and decoherence in the presence of fast local control. We show how the models resolve the paradoxes.
We analyze the quantum-to-classical transition of interacting systems from the viewpoint of reduced dynamical closure. Bohmian trajectories are used as a diagnostic of the probability flow generated by the full wavefunction, rather than as an alternative set of quantum predictions. A closed classical or semiclassical d...
Decoherence in quantum systems is conventionally modeled as the effect of interactions with an external environment. However, such a prescription excludes isolated many-body systems, which are also expected to display classical behavior at macroscopic scales. In isolated systems, decoherence must emerge internally from...
S. Pilatowsky-Cameo, Jordan S. Cotler, Daniel Ranard et al.· 1 citation· ⚡1
We study effective spin interactions arising from quantum electrodynamics (QED) scattering between localized fermionic spins. By integrating out photon and mediator fields, the dynamics reduce to an effective spin Hamiltonian. For two qubits in the nonrelativistic regime, the resulting interaction takes a tensor dipola...
We argue for the universality of quantum theory using a dynamical consistency argument, within a specific Hamiltonian setting. We analyse two different types of coupling between simple quantum harmonic oscillators. Each illustrates an aspect of the free and interacting quantum fields and shows the inadequacy of semicla...
We investigate the open quantum dynamics of a system of two masses interacting with an environment of linearized gravitational waves. We formulate the analysis in terms of the observable proper distance between the two masses, and show that the canonical variables obtained from the standard Lagrangian, expressed in ter...
O. Angeli, Anirudh Gundhi, Angelo Bassi· 0 citations
In recent years, new theoretical insights into decoherence and quantum measurements have emerged through the study of many-body dynamics in isolated quantum systems. It is now understood that the parameters and energy scales in system-environment interactions decisively affect how readily information spreads from a qua...
K. Schneeweiss, Tom Rivlin, Maximilian P. E. Lock et al.· 1 citation
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