Dynamical reduction models propose a solution to the measurement problem in quantum mechanics: the collapse of the wave function becomes a physical process. We compute the predictions to decaying and flavor-oscillating neutral mesons for the two most promising collapse models, the QMUPL (Quantum Mechanics with Universal Position Localization) model and the mass-proportional CSL (Continuous Spontaneous Localization) model. Our results are showing (i) a strong sensitivity to the very assumptions of the noise field underlying those two collapse models and (ii) under particular assumptions the CSL case allows even to recover the decay dynamics. This in turn allows to predict the effective collapse rates solely based on the measured values for the oscillation (mass differences) and the measured values of the decay constants. The four types of neutral mesons (Kmeson, D-meson, B d -meson, Bs-meson) lead surprisingly to ranges comparable to those put forward by Adler (2007) and Ghirardi-Rimini-Weber (1986). Our results show that these systems at high energies are very sensitive to possible modifications of the standard quantum theory making them a very powerful laboratory to rule out certain collapse scenarios and studying the detailed physical processes solving the measurement problem.

We characterize the impact that the application of two maps in a quantum-controlled order has on the process of work extraction via unitary cycles and its optimization. e control is based on the quantum switch model that applies maps in an order not necessarily compatible with the underlying causal structure and, in principle, can be implemented experimentally. First, we show that the activation of quantum maps through the quantum switch model always entails a non-negative gain in ergotropy compared to their consecutive application. We also establish a condition that the maps should ful ll in order to achieve a non-zero ergotropic gain. We then perform a thorough analysis of maps applied to a two-level system and provide general conditions for achieving a positive gain on the incoherent part of ergotropy. Our results are illustrated with several examples and applied to qubit and 𝑑-dimensional quantum systems. In particular, we demonstrate that a non-zero work can be extracted from a system thermalized by two coherently controlled reservoirs.

We study the probability oscillations of mixed particles in the presence of self-gravitational interaction. We show a breaking of the CPT-symmetry due to the contemporary violation of the T-symmetry and the CPsymmetry preservation. This violation is directly associated to the rising of the entanglement among the elements of the system that can be seen as a pure many-body effect scaling with the number of the elements in the system. This effect could have played a relevant role in the first stages of the Universe or in core of very dense systems. Experiments based on Rydberg atoms confined in microtraps can simulate the mixing and the mutual interaction and could allow to test the mechanism here presented.

The dynamics of a quantum system with internal degrees of freedom undergoing spontaneous collapse in the position basis are analysed; e.g., neutral mesons or neutrinos. Surprisingly, the value of the Heaviside function θ(x) at x = 0 that can in general be chosen in the interval [0,1] leads to different physical predictions. For the QMUPL (Quantum Mechanics with Universal Position Localization) model only a single value leads to probabilities conserving the particle number. Herewith the physical properties of the noise field can be constrained. This opens a road to study the physical properties of the noise field essential for collapse models.PACS numbers: 03.65.-w, 03.65.Tu, 05.40.-a Dynamical reduction models have been shown to be proper frameworks to circumvent the measurement problem of standard quantum mechanics and allow for a clear definition of a microscopic and a macroscopic system, respectively. In their seminal work [1] Ghirardi, Rimini and Weber introduced a concise framework for microscopic and macroscopic physical systems by introducing a spontaneous collapse of the wave function. Mathematically, this can be achieved by adding specific nonlinear and stochastic terms to the Schrdinger equation. The stochasticity is required to avoid superluminal signaling in general. Up to date such modifications of the unitary evolution have not been found to be in conflict to any experiment. The testability of collapse models is one of its merits and experiments such as, e.g., the ones with X-rays [2, 3] are putting upper limits on the reduction rate parameter. In this letter we are not interested per se to single out an experimental testable observable, we focus on conceptual issues when considering systems at high energies. We will prove that the mathematical structure of the interaction with the noise field leads to constraints if one imposes particle number conservation.In general, the dynamics is described by the following non-linear stochastic differential equation [4]with = 1 and  i t := φ t | i |φ t . HereĤ is the standard Hamiltonian of the quantum system, i are a set of N operators introducing the collapse in a certain basis choice (position basis in most cases). W i,t present a set of independent standard Wiener processes and λ quantifies the strength of the collapse. Finding solutions to a non-linear stochastic equation is a cumbersome problem. A first step to simplify the issue is to replace the real noises introduced via W i,t by imaginary ones iW i,t . As shown in Ref.[5] this does not change the master equation of the corresponding density operator: the physics is left invariant. Via that "imaginary transformation", equation (1) becomes a Schrödinger-like equation with a random Hamiltonianwhere w i,t := dWi,t dt . In the following we focus on the QMUPL (Quantum Mechanics with Universal Position Localization) model [6,7] for one particle (N = 1), which is one of the conceptually simplest spontaneous reduction models, however, the results we draw are not limited to this model. Accordingly the opera...

Abstract. Why do we never see a table in a superposition of here and there? This problem gets a solution by so called collapse models assuming the collapse as a genuinely physical process. Here we consider two specific collapse models and apply them to systems at high energies, i.e. flavour oscillating neutral meson systems. We find on one hand a potentially new interpretation of the decay rates introduced by hand in the standard formalism and on the other hand that these systems at high energies constrain by experimental data the possible collapse scenarios.