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In order to resolve the measurement problem of Quantum Mechanics, non-unitary time evolution has been derived from the unitarity of standard quantum formalism. New wave functions of free and non-free quantum systems follow from Schroedinger…

Quantum Physics · Physics 2007-05-23 Pradip Kumar Chatterjee

The problem of measurement in quantum mechanics is that the quantum particle in the course of evolution, as described by the linear Schrodinger equation, exists in all of its possible states, but in measuring, the particle is always…

Quantum Physics · Physics 2013-11-04 Alexey V. Melkikh

Three problems stand in the way of deriving classical theories from quantum mechanics: those of realist interpretation, of classical properties and of quantum measurement. Recently, we have identified some tacit assumptions that lie at the…

Quantum Physics · Physics 2015-06-03 Petr Hajicek

In the mid-19th century, both the laws of mechanics and thermodynamics were known, and both appeared fundamental. This was changed by Boltzmann and Gibbs, who showed that thermodynamics can be *derived*, by applying mechanics to very large…

Quantum Physics · Physics 2021-07-05 Vyacheslav Lysov , Yasha Neiman

Starting from a new principle inspired by quantum tomography rather than from Born's rule, this paper gives a self-contained deductive approach to quantum mechanics and quantum measurement. A suggestive notion for what constitutes a quantum…

Quantum Physics · Physics 2024-05-22 Arnold Neumaier

Considering the recently established arbitrariness the Schroedinger equation has to be interpreted as an equation of motion for a statistical ensemble of particles. The statistical qualities of individual particles derive from the unknown…

Quantum Physics · Physics 2008-02-03 W. A. Hofer

The notorious quantum measurement problem brings out the difficulty to reconcile two quantum postulates: the unitary evolution of closed quantum systems and the wave-function collapse after a measurement. This problematics is particularly…

Quantum Physics · Physics 2022-08-24 George Moreno , Ranieri Nery , Cristhiano Duarte , Rafael Chaves

An early approach to include pointers representing measurement devices into quantum mechanics was given by von Neumann. Based on this idea, we model such pointers by qubits and couple them to a free particle, in analogy to a classical…

Quantum Physics · Physics 2021-10-22 Bernd Konrad , Fabio Di Pumpo , Matthias Freyberger

We consider the dynamics of a continuously monitored qubit in the limit of strong measurement rate where the quantum trajectory is described by a stochastic master equation with Poisson noise. Such limits are expected to give rise to…

Quantum Physics · Physics 2025-04-24 Alan Sherry , Cedric Bernardin , Abhishek Dhar , Aritra Kundu , Raphael Chetrite

We propose a theory of quantum (statistical) measurement which is close, in spirit, to Hepp's theory, which is centered on the concepts of decoherence and macroscopic (classical) observables, and apply it to a model of the Stern-Gerlach…

Mathematical Physics · Physics 2023-03-01 Walter F. Wreszinski

A non-Markovianity measure for quantum channels is introduced based on causality measure - a monotone of causal (temporal) correlations - arising out of the pseudo-density matrix (PDM) formalism which treats quantum correlations in space…

Quantum Physics · Physics 2021-02-04 Shrikant Utagi

The origin of non-classical correlations is difficult to identify since the uncertainty principle requires that information obtained about one observable invariably results in the disturbance of any other non-commuting observable. Here,…

Quantum Physics · Physics 2014-07-01 Holger F. Hofmann

The measurement postulate of quantum theory stands in conflict with the laws of thermodynamics and has evoked debate regarding what actually constitutes a measurement. With the help of modern quantum statistical mechanics, we take the first…

Quantum Physics · Physics 2025-12-16 Emanuel Schwarzhans , Felix C. Binder , Marcus Huber , Maximilian P. E. Lock

To elucidate ideal measurements, one must explain how individual events emerge from quantum theory which deals with statistical ensembles, and how different may end up with different final states. This so-called "measurement problem" is…

Quantum Physics · Physics 2017-10-04 Armen E. Allahverdyan , Roger Balian , Theo M. Nieuwenhuizen

Quantum metrology pursues high-precision measurements of physical quantities by using quantum resources. However, the decoherence generally hinders its performance. Previous work found that the metrological error tends to diverge in the…

Quantum Physics · Physics 2021-11-04 Wei Wu , Jun-Hong An

A history and drama of the development of quantum probability theory is outlined starting from the discovery of the Plank's constant exactly a 100 years ago. It is shown that before the rise of quantum mechanics 75 years ago, the quantum…

Probability · Mathematics 2007-05-23 V. P. Belavkin

One of the most striking features of quantum mechanics is the profound effect exerted by measurements alone. Sophisticated quantum control is now available in several experimental systems, exposing discrepancies between quantum and…

Despite its age, quantum theory still suffers from serious conceptual difficulties. To create clarity, mathematical physicists have been attempting to formulate quantum theory geometrically and to find a rigorous method of quantization, but…

Quantum Physics · Physics 2017-09-28 Maik Reddiger

In spite of the innumerable attempts to resolve the quantum measurement problem, almost since its beginning a century ago, a satisfactory solution still remains elusive. However, after the advent of quantum entanglement leading to…

General Physics · Physics 2025-04-29 Mani L. Bhaumik

The main purpose of this paper is to review the progress that has taken place so far in the search for a single unifying principle that harmonizes (i) the wave and particle natures of matter and radiation, both at the quantum and the…

Quantum Physics · Physics 2015-02-12 Partha Ghose