Reduced dynamics need not be completely positive.

By P. Pechukas. 1994

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Citations in the corpus

Dynamics of initially entangled open quantum systems (2004, background): “The first step, which Pechukas [36] did, is to show that every purestate density matrix ρA is assigned a product density matrix, as in (C.”
Colloquium: Non-Markovian dynamics in open quantum systems (2015, background): “However, experimentalists often study fast processes in strongly coupled systems, where this independence is rarely the case, as originally pointed out by Pechukas (1994).”
The classical-quantum boundary for correlations: Discord and related measures (2011, background): “The assignment map (Pechukas, 1994; Rodŕıguez-Rosario et al., 2010) takes the system state to a correlated state of the systemenvironment.”
Dynamics of non-Markovian open quantum systems (2015, background): “In addition, as argued by Liu et al. (2011); Meier and Tannor (1999); Pechukas (1994); and Smirne et al. (2011), there are situations that are experimentally relevant where the system and the environment are initially correlated.”
Quantum Information and Relativity Theory (2002, background): “However, the CP requirement may fail if there is a prior entanglement with another system and the dynamics is not factorizable (Pechukas, 1994; Štelmachovič and Bužek, 2001; Salgado and Sánchez-Gómez, 2002).”
Introduction to Quantum Thermodynamics: History and Prospects (2018, background): “This has been challenged by Pechukas [50] who claimed that positivity of the dynamical map is sufficient.”
Completely positive maps and classical correlations (2007, background): “For one, the dynamical map is usually not completely positive and very often not even positive [7].”
Delocalized excitons in natural light-harvesting complexes (2018, background): “As is well-known, the 2nd order approximation with respect to the system-bath interaction causes the QME to be non-positive definite, without rotating wave approximation (Kohen et al., 1997; Pechukas, 1994), and to be unreliable as the system-bath interaction becomes larger.”
Nonequilibrium fluctuations, fluctuation theorems, and counting statistics in quantum systems (2008, unknown): “Without RWA, the Markovian QME generator can lead to a positivity breakdown for certain set of initial conditions due to small errors introduced on the initial short-time dynamics by the Markovian approximation [30, 81, 101, 109, 142, 171].”