Bifurcation in Quantum Measurement

We present a generic model of (non-destructive) quantum measurement. Being formulated within reversible quantum mechanics, the model illustrates a mechanism of a measurement process --- a transition of the measured system to an eigenstate of the measured observable. The model consists of a two-level system $\mu$ interacting with a larger system $A$, consisting of smaller subsystems. The interaction is modelled as a scattering process. Restricting the states of $A$ to product states leads to a bifurcation process: In the limit of a large system $A$, the initial states of $A$ that are efficient in leading to a final state are divided into two separated subsets. For each of these subsets, $\mu$ ends up in one of the eigenstates of the measured observable. The probabilities obtained in this branching confirm the Born rule.Comment: A revised version that includes a more general presentation of the model (in Sect. 4) and a larger revision of the Introductio

Scattering theory of the bifurcation in quantum measurement

We model quantum measurement of a two-level system $\mu$. Previous obstacles for understanding the measurement process are removed by basing the analysis of the interaction between $\mu$ and the measurement device on quantum field theory. We show how microscopic details of the measurement device can influence the transition to a final state. A statistical analysis of the ensemble of initial states reveals that those initial states that are efficient in leading to a transition to a final state, result in either of the expected eigenstates for $\mu$, with probabilities that agree with the Born rule.Comment: Change of title and minor revisions of main text and supplemental material; main text 8 pages, 2 figures; supplemental material 9 pages, 2 figure

Quantum Field Theory with Classical Sources - Linearized Quantum Gravity

In a previous work and in terms of an exact quantum-mechanical framework, $\hbar$-independent causal and retarded expectation values of the second-quantized electro-magnetic fields in the Coulomb gauge were derived in the presence of a conserved classical electric current. The classical $\hbar$-independent Maxwell's equations then naturally emerged. In the present work, we extend these considerations to linear gravitational quantum deviations around a flat Minkowski space-time in a Coulomb-like gauge. The emergence of the classical causal and properly retarded linearized classical theory of general relativity with a conserved classical energy-momentum tensor is then outlined. The quantum-mechanical framework also provides for a simple approach to classical quadrupole gravitational radiation of Einstein and microscopic spontaneous graviton emission and/or absorption processes

Uppvärmning av Almunge brandstation med pyrolys

This project has been carried out on the behalf of Ihus in collaboration with Stuns Energi. The goal was to find and model a solution based on the process of pyrolysis that can deliver enough heat to Almunge fire station while storing maximum amount of CO2 in the form of biochar. Two systems that primarily used waste heat from a pyrolysis reactor were studied. In one case a wood pellet boiler was used to cover peak load and the second system used a coal boiler that uses some of the coal produced in the reactor. The result shows that both solutions can theoretically deliver the required amount of heat and have lower emissions of carbon dioxide than the current method of heat generation used on the property, a wood pellet boiler. A model of the system that uses a coal boiler shows that it, under a period of one year, releases 5 % more CO2, has a 60 % higher amount of unused waste heat, and consumes 22 % more substrate per month than the system that uses a wood pellet burner. However, the coal boiler resulted in 18 % higher in biochar production, potentially 33 % more coal bound if the produced biochar is used as a carbon sink, and 18 % higher economical value after 20 years.Detta projekt har genomf¨orts p˚a best¨allning av Ihus i samarbete med Stuns Energi. Det gick ut p˚a att hitta och modellera en energil¨osning, baserad p˚a en pyrolysprocess, som f¨orser en brandstation i Almunge med den v¨arme stationen kr¨aver p˚a m˚anadsbasis samtidigt som maximal m¨angd CO2 binds i form av biokol. Tv˚a system som prim¨art anv¨ander spillv¨arme fr˚an en pyrolysreaktor i uppv¨armningssyftet togs fram. I ena fallet anv¨ands en pelletspanna f¨or att t¨acka de effekttopparna som kan uppst˚a och det andra systemet anv¨ander sig av en kolpanna som matas med kolet fr˚an pyrolysprocessen. Resultatet visar att b˚ada l¨osningar kan teoretiskt leverera den m¨angden v¨arme fastigheten kr¨aver och har l¨agre utsl¨app av koldioxid ¨ an den nuvarande d¨ar fastigheten endast v¨arms upp av en pelletspanna. Systemet som anv¨ander sig av kolpannan visade sig under ett ˚ars period sl¨appa ut 5 % mer CO2, har 60 % st¨orre andel av ej utnyttjad spillv¨arme och konsumerar 22 % mer substrat per m˚anad ¨an systemet med pelletspannan men kompenserade det med 18 % h¨ogre produktion av biokol, potentiellt 33 % st¨orre m¨angd kol som binds om biokolet anv¨ands som kols¨anka och 18 % h¨ogre ekonomiskt v¨arde efter 20 ˚ar