The measurement postulates of quantum mechanics are operationally redundant

Understanding the core content of quantum mechanics requires us to disentangle the hidden logical relationships between the postulates of this theory. Here we show that the mathematical structure of quantum measurements, the formula for assigning outcome probabilities (Born's rule) and the post-measurement state-update rule, can be deduced from the other quantum postulates, often referred to as "unitary quantum mechanics", and the assumption that ensembles on finite-dimensional Hilbert spaces are characterised by finitely many parameters. This is achieved by taking an operational approach to physical theories, and using the fact that the manner in which a physical system is partitioned into subsystems is a subjective choice of the observer, and hence should not affect the predictions of the theory. In contrast to other approaches, our result does not assume that measurements are related to operators or bases, it does not rely on the universality of quantum mechanics, and it is independent of the interpretation of probability.Comment: This is a post-peer-review, pre-copyedit version of an article published in Nature Communications. The final authenticated version is available online at: http://dx.doi.org/10.1038/s41467-019-09348-

Weak Deeply Virtual Compton Scattering

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.Comment: 30 pages, 11 figure

Induced Gamma-band Activity Elicited by Visual Representation of Unattended Objects

Peer reviewedPostprin

Response to "The measurement postulates of quantum mechanics are not redundant"

Adrian Kent has recently presented a critique [arXiv:2307.06191] of our paper [Nat. Comms. 10, 1361 (2019)] in which he claims to refute our main result: the measurement postulates of quantum mechanics can be derived from the rest of postulates, once we assume that the set of mixed states of a finite-dimensional Hilbert space is finite-dimensional. To construct his argument, Kent considers theories resulting from supplementing quantum mechanics with hypothetical "post-quantum" measurement devices. We prove that each of these theories contains pure states (i.e. states of maximal knowledge) which are not rays of the Hilbert space, in contradiction with the "pure state postulate" of quantum mechanics. We also prove that these alternatives violate the finite-dimensionality of mixed states. Each of these two facts separately invalidates the refutation. In this note we also clarify the assumptions used in the above-cited paper and discuss the notions of pure state, physical system, and the sensitivity of the structure of the state space under modifications of the measurements or the dynamics.Comment: 7 page

Insights into receptor structure and dynamics at the surface of living cells

Evaluating protein structures in living cells remains a challenge. Here, we investigate Interleukin-4 receptor alpha (IL-4Rα) into which the non-canonical amino acid bicyclo[6.1.0]nonyne-lysine (BCNK) is incorporated by genetic code expansion. Bioorthogonal click labeling is performed with tetrazine-conjugated dyes. To quantify the reaction yield in situ, we develop brightness-calibrated ratiometric imaging, a protocol where fluorescent signals in confocal multi-color images are ascribed to local concentrations. Screening receptor mutants bearing BCNK in the extracellular domain uncovered site-specific variations of both click efficiency and Interleukin-4 binding affinity, indicating subtle well-defined structural perturbations. Molecular dynamics and continuum electrostatics calculations suggest solvent polarization to determine site-specific variations of BCNK reactivity. Strikingly, signatures of differential click efficiency, measured for IL-4Rα in ligand-bound and free form, mirror sub-angstrom deformations of the protein backbone at corresponding locations. Thus, click efficiency by itself represents a remarkably informative readout linked to protein structure and dynamics in the native plasma membrane

Time Correlation Functions of Three Classical Heisenberg Spins on an Isosceles Triangle and on a Chain: Strong Effects of Broken Symmetry

At arbitrary temperature $T$, we solve for the dynamics of single molecule magnets composed of three classical Heisenberg spins either on a chain with two equal exchange constants $J_1$, or on an isosceles triangle with a third, different exchange constant $J_2$. As T\rightrarrow\infty, the Fourier transforms and long-time asymptotic behaviors of the two-spin time correlation functions are evaluated exactly. The lack of translational symmetry on a chain or an isosceles triangle yields time correlation functions that differ strikingly from those on an equilateral trinagle with $J_1=J_2$. At low $T$, the Fourier transforms of the two autocorrelation functions with $J_1\ne J_2$ show one and four modes, respectively. For a semi-infinite $J_2/J_1$ range, one mode is a central peak. At the origin of this range, this mode has a novel scaling form.Comment: 9 pages, 14 figures, accepted for publication in Phys. Rev.

Spatio-temporal distribution of induced seismicity in flooded mines in the Ruhr area - interpretation by geomechanical numerical modelling

Induced seismicity during mine flooding is the focus of the FloodRisk project. One of the study areas is the Ruhr area, which is characterised by centuries of intensive coal mining. After the closure of the last mines, controlled flooding began. Within the FloodRisk project, we investigate ground uplift, stress changes due to pore pressure changes and the reactivation potential of faults to explain induced seismicity. We concentrate on the seismicity monitoring and geomechanics of the Haus Aden catchment, for which we investigate the relationship between water rise, tectonic stress and induced seismicity. The monitoring of seismicity is based on a network of up to 30 short-period seismic stations installed by the Ruhr University in the area of the former "Bergwerk Ost", which exhibited the highest seismicity in the Ruhr area during active mining. The stations cover an area of about 160 km 2 and are spaced between 0.5 and 3.5 km apart. They allow continuous monitoring of seismicity. Since 2019, more than 2200 induced events have been localised. A prerequisite for the interpretation of seismicity is a detailed localisation of the events. The relative localisation of the induced earthquakes has significantly reduced the location uncertainty and allowed the spatial and temporal evolution of earthquake clusters due to the rise in mine water levels to be studied. The resulting pattern of seismicity was compared with known underground structures. This comparison indicates that most of the events occur approximately 300 m below the main pillars between the longwall panels in the already flooded deepest level of the mine. A generic FE numerical model was developed for a section of the Heinrich Robert mine based on the geometry of the pillars, shafts and longwall panels. The stress data for model calibration are based on a compilation of the regional stress state in the eastern Ruhr area. For this purpose, hydraulic fracture tests carried out in the mines to minimise rock bursts were re-evaluated and compared with stress orientations derived from independent sources such as borehole fractures and earthquake source mechanisms. Using this 3D numerical approach, we conclude that there is increased vertical stress within and below the pillars as a result of stress arching. As the horizontal stress changes below the mine levels are small, this results in increasing differential stresses that can lead to the observed events below the mine level when the mine water level rises

Butterfly hysteresis loop at non-zero bias field in antiferromagnetic molecular rings: cooling by adiabatic magnetization

At low temperatures, the magnetization of the molecular ferric wheel NaFe$_6$ exhibits a step at a critical field $B_c$ due to a field-induced level-crossing. By means of high-field torque magnetometry we observed a hysteretic behavior at the level-crossing with a characteristic butterfly shape which is analyzed in terms of a dissipative two-level model. Several unusual features were found. The non-zero bias field of the level-crossing suggests the possibility of cooling by adiabatic magnetization.Comment: 4 pages, 5 figures, REVTEX4, to appear in PR