arXiv subjects

Ansgar Pernice

Publications and source records attributed to Ansgar Pernice.

3 recordsLinked to original sources

arXiv2026

Signature structure of quadratic response under Zeno-Schur coarse graining in open quantum systems

Quadratic response tensors arise naturally in quantum kinetic descriptions, such as the quantum linear Boltzmann equation (QLBE), where they encode the coupled structure of drift and fluctuations beyond simple positive-definite forms. Motivated by this class of systems, we investigate how such response structures are modified under monitoring-induced coarse graining. Within the Gorini--Kossakowski--Sudarshan--Lindblad (GKSL) framework and under time-scale separation, Zeno elimination of fast degrees of freedom generates a subtractive renormalization with Schur-complement structure. As a result, positive definiteness of the response tensor is not preserved: coupling between slow and rapidly damped sectors can induce negative directions even when the microscopic tensor is strictly positive. We formulate a minimal effective flow capturing this mechanism and show that the competition between Schur-induced compression and anisotropic perturbations organizes the dynamics into distinct signature sectors. The resulting structure appears to be robust within the class of models considered and, in appropriate regimes, may be experimentally accessible. Our results establish a general framework for how quadratic response structures, as encountered in QLBE-type dynamics, are dynamically reorganized under Zeno-induced coarse graining.

quant-ph↗

arXiv2026

Zeno-Constrained Formation of Relativistic Mass Shells

We study an extension of the quantum linear Boltzmann equation describing irreversible momentum-space dynamics of an open quantum system under strong continuous monitoring. The monitored observable is taken to be a quadratic form in an extended, purely Euclidean four-dimensional momentum space, without assuming any fixed signature at the microscopic level. In the resulting quantum Zeno regime, rapid suppression of off-constraint excursions allows for an adiabatic elimination of fast degrees of freedom. Using a Schur-complement construction, the induced second-order corrections give rise to an effective flow of the monitored quadratic form under temporal coarse graining. Under mild isotropy assumptions on the underlying momentum-mixing dynamics and an appropriate calibration condition, this flow approaches an infrared fixed point characterized by a quadratic form of Lorentzian signature. The corresponding null set defines a mass-shell-like constraint surface that governs the long-time Zeno-projected dynamics and whose isometry group matches the kinematic structure of Lorentz transformations at the effective level. Familiar relativistic features, including Maxwell-Juettner-type stationary distributions, arise at the level of the effective infrared description as consequences of this fixed point within the extended quantum Boltzmann framework.

quant-ph↗

arXiv2012

System-environment correlations and Non-Markovian dynamics

We determine the total state dynamics of a dephasing open quantum system using the standard environment of harmonic oscillators. Of particular interest are random unitary approaches to the same reduced dynamics and system-environment correlations in the full model. Concentrating on a model with an at times negative dephasing rate, the issue of "non-Markovianity" will also be addressed. Crucially, given the quantum environment, the appearance of non-Markovian dynamics turns out to be accompanied by a loss of system-environment correlations. Depending on the initial purity of the qubit state, these system-environment correlations may be purely classical over the whole relevant time scale, or there may be intervals of genuine system-environment entanglement. In the latter case, we see no obvious relation between the build-up or decay of these quantum correlations and "Non-Markovianity".

quant-ph↗