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The spin-coherent-state positive-operator-valued-measure (POVM) is a fundamental measurement in quantum science, with applications including tomography, metrology, teleportation, benchmarking, and measurement of Husimi phase space…

Quantum Physics · Physics 2018-10-03 Ezad Shojaee , Christopher S. Jackson , Carlos A. Riofrio , Amir Kalev , Ivan H. Deutsch

Wigner functions provide a way to do quantum physics using quasiprobabilities, that is, "probability" distributions that can go negative. Informationally complete POVMs, a much younger subject than phase space formulations of quantum…

Quantum Physics · Physics 2020-10-07 John B. DeBrota , Blake C. Stacey

We demonstrate in this paper that the probabilities for sequential measurements have features very different from those of single-time measurements. First, they cannot be modelled by a classical stochastic process. Second, they are…

Quantum Physics · Physics 2009-11-11 Charis Anastopoulos

I provide a prescription to define space, at a given moment, for an arbitrary observer in an arbitrary (sufficiently regular) curved space-time. This prescription, based on synchronicity (simultaneity) arguments, defines a foliation of…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. Lachièze-Rey

It is well-known in quantum information theory that a positive operator valued measure (POVM) is the most general kind of quantum measurement. Mathematically, a quantum probability is a normalised POVM, namely a function on certain subsets…

Quantum Physics · Physics 2022-12-06 Kyler S. Johnson , Michael J. Kozdron

We propose a stochastic interpretation of spacetime non-commutativity starting from the path integral formulation of quantum mechanical commutation relations. We discuss how the (non-)commutativity of spacetime is inherently related to the…

High Energy Physics - Theory · Physics 2025-03-12 Michele Arzano , Folkert Kuipers

We propose a scheme that can realize a class of positive-operator-valued measures (POVMs) by performing a sequence of projective measurements on the original system, in the sense that for an arbitrary input state the probability…

Quantum Physics · Physics 2007-05-23 Guoming Wang , Mingsheng Ying

The second-order differential equation for a damped harmonic oscillator can be converted to two coupled first-order equations, with two two-by-two matrices leading to the group $Sp(2)$. It is shown that this oscillator system contains the…

Mathematical Physics · Physics 2016-04-06 Sibel Baskal , Young S. Kim , Marilyn E. Noz

We discuss the problem of time in quantum mechanics. In the traditional formulation time enters the model as a~parameter, not an observable. In our model time is a quantum observable as any other quantum quantity and it is also a component…

Quantum Physics · Physics 2023-03-13 Andrzej Góźdź , Marek Góźdź , Aleksandra Pędrak

Motivated by a recent proposal (by Koslowski-Sahlmann) of a kinematical representation in Loop Quantum Gravity (LQG) with a nondegenerate vacuum metric, we construct a polymer quantization of the parametrised massless scalar field theory on…

General Relativity and Quantum Cosmology · Physics 2013-09-12 Sandipan Sengupta

This work explores the behaviour of a noncommutative harmonic oscillator in a time-dependent background, as previously investigated in [1]. Specifically, we examine the system when expressed in terms of commutative variables, utilizing a…

Quantum Physics · Physics 2024-07-10 Manjari Dutta , Shreemoyee Ganguly , Sunandan Gangopadhyay

We construct an effective commutative Schr\"odinger equation in Moyal space-time in $(1+1)$-dimension where both $t$ and $x$ are operator-valued and satisfy $\left[ \hat{t}, \hat{x} \right] = i \theta$. Beginning with a time-reparametrised…

Quantum Physics · Physics 2017-08-17 Partha Nandi , Sayan Kumar Pal , Aritra N Bose , Biswajit Chakraborty

A model in which pointlike defects are randomly embedded in Minkowski spacetime is considered. The distribution of spacetime defects is constructed to be Lorentz-invariant. It does not introduce a preferred reference frame, because it is…

High Energy Physics - Theory · Physics 2013-12-16 M. Schreck , F. Sorba , S. Thambyahpillai

There are good reasons to suspect that spacetime at Planck scales is noncommutative. Typically this noncommutativity is controlled by fixed "vectors" or "tensors" with numerical entries. For the Moyal spacetime, it is the antisymmetric…

High Energy Physics - Theory · Physics 2014-11-20 A. P. Balachandran , Anosh Joseph , Pramod Padmanabhan

Quantum-mechanical observables for spatial and spacetime localization are considered from a lattice-theoretic perspective. It is shown that when replacing the lattice of all complex orthogonal projections underlying the Born rule by the…

Mathematical Physics · Physics 2026-02-13 Gandalf Lechner , Ivan Romualdo de Oliveira

A Lorentz invariant model for gravity-induced quantum state reduction is presented, which is mainly developed from Penrose's argument that the time translation operator in a superposition of macroscopic states is ill-defined. The problem to…

Quantum Physics · Physics 2017-01-16 Garrelt Quandt-Wiese

The objective of this work is to develop a recursive, discrete time quantum filtering equation for a system that interacts with a probe, on which measurements are performed according to the Positive Operator Valued Measures (POVMs)…

Quantum Physics · Physics 2013-09-10 Ram A. Somaraju , Alain Sarlette , Hugo Thienpont

We present a method for measuring quantum states encoded in the temporal modes of photons. The basis for the multilevel quantum states is defined by the use of modes propagating in a dispersive medium, which is a fiber in this case. The…

Quantum Physics · Physics 2020-11-26 Karolina Sedziak-Kacprowicz , Artur Czerwinski , Piotr Kolenderski

We address the problem of quantum nonlocality with positive operator valued measures (POVM) in the context of Einstein-Podolsky-Rosen quantum steering. We show that, given a candidate for local hidden state (LHS) ensemble, the problem of…

Quantum Physics · Physics 2018-08-15 H. Chau Nguyen , Antony Milne , Thanh Vu , Sania Jevtic

A reference frame F is described by the element g of the Poincare' group P which connects F with a given fixed frame F_0. If F is a quantum frame, defined by a physical object following the laws of quantum physics, the parameters of g have…

Quantum Physics · Physics 2015-06-26 S. Mazzucchi