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The tomographic description of a quantum state is formulated in an abstract infinite dimensional Hilbert space framework, the space of the Hilbert-Schmidt linear operators, with trace formula as scalar product. Resolutions of the unity,…

Quantum Physics · Physics 2007-05-23 V. I. Man'ko , G. Marmo , A. Simoni , F. Ventriglia

Since the advent of quantum mechanics we have mainly been concerned with its predictions from the perspective of an external observer. This is in strong contrast to the theory of general relativity, where the physics is governed by the…

Quantum Physics · Physics 2014-11-17 Dries Sels , Michiel Wouters

By applying the projector to the filled lattice eigenstates on a specific position, or applying the local electron annihilation operator on the many-body ground state, one can construct a quantum state localized around a specific position…

Mesoscale and Nanoscale Physics · Physics 2025-03-06 Lucas A. Oliveira , Wei Chen

Quantum probability provides a novel framework for formulating machine-learning (ML) problems in Hilbert space. We introduce a prototype-based learning scheme where class representatives are encoded as generative matrix product states…

Quantum Physics · Physics 2026-05-19 Kun Zhang , Lei Ding , Sheng-Chen Bai , Jing Sun , An-Qi Jing , Min Tang , Shi-Ju Ran

In two recent papers by the author, a new approach was suggested for quantising space-time, or space. This involved developing a procedure for quantising a system whose configuration space--or history-theory analogue--is the set of objects,…

General Relativity and Quantum Cosmology · Physics 2007-05-23 C. J. Isham

Let $H$ be either a complex inner product space of dimension at least two, or a real inner product space of dimension at least three. Let us fix an $\alpha\in \left(0,\tfrac{\pi}{2}\right)$. The purpose of this paper is to characterize all…

Mathematical Physics · Physics 2018-05-21 György Pál Gehér

The manifold of pure quantum states is a complex projective space endowed with the unitary-invariant geometry of Fubini and Study. According to the principles of geometric quantum mechanics, the detailed physical characteristics of a given…

Quantum Physics · Physics 2015-06-26 Dorje C. Brody , Lane P. Hughston

We introduce Superstate Quantum Mechanics (SQM), a theory that considers states in Hilbert space subject to multiple quadratic constraints, with ``energy'' also expressed as a quadratic function of these states. Traditional quantum…

We consider the manifold of all quantum many-body states that can be generated by arbitrary time-dependent local Hamiltonians in a time that scales polynomially in the system size, and show that it occupies an exponentially small volume in…

Quantum Physics · Physics 2011-05-12 David Poulin , Angie Qarry , R. D. Somma , Frank Verstraete

Quantum theory of field (extended) objects without a priori space-time geometry has been represented. Intrinsic coordinates in the tangent fibre bundle over complex projective Hilbert state space $CP(N-1)$ are used instead of space-time…

General Physics · Physics 2007-05-23 Peter Leifer

It is shown that from the expectation values of obervables, which can be measured for a single system using protective measurements, the linear structure, inner product, and observables in the Hilbert space can be reconstructed. A universal…

High Energy Physics - Theory · Physics 2009-10-22 J. Anandan

To get out of logical deadlock in interpreting gedanken experiments like Schrodinger cat, actual meaning of a wave function, or a state, in the case of complex two-dimensional Hilbert space, is shown to represent transformations executing…

General Physics · Physics 2014-08-29 Alexander M. Soiguine

In this paper, we investigate the connection between Classical and Quantum Mechanics by dividing Quantum Theory in two parts: - General Quantum Axiomatics (a system is described by a state in a Hilbert space, observables are self-adjoint…

Quantum Physics · Physics 2009-11-07 H. Bergeron

In this paper we conjecture the existence of a new "ground" state in quantum gravity, supplying a wave function for the inflationary Universe. We present its explicit perturbative expression in the connection representation, exhibiting the…

General Relativity and Quantum Cosmology · Physics 2012-07-04 Joao Magueijo , Laura Bethke

$\mathcal{PT}$-symmetric quantum mechanics has been considered an important theoretical framework for understanding physical phenomena in $\mathcal{PT}$-symmetric systems, with a number of $\mathcal{PT}$-symmetry related applications. This…

Quantum Physics · Physics 2019-12-25 Da-Jian Zhang , Qing-hai Wang , Jiangbin Gong

We constructed a Hilbert space representation of a contextual Kolmogorov model. This representation is based on two fundamental observables -- in the standard quantum model these are position and momentum observables. This representation…

Quantum Physics · Physics 2015-06-26 Andrei Khrennikov

Quantum computation is based on tensor products and entangled states. We discuss an alternative to the quantum framework where tensor products are replaced by geometric products and entangled states by multivectors. The resulting theory is…

Quantum Physics · Physics 2008-01-16 Diederik Aerts , Marek Czachor

Hilbert space combines the properties of two fundamentally different types of mathematical spaces: vector space and metric space. While the vector-space aspects of Hilbert space, such as formation of linear combinations of state vectors,…

Quantum Physics · Physics 2015-05-27 I. D'Amico , J. P. Coe , V. V. Franca , K. Capelle

Most states in the Hilbert space are maximally entangled. This fact has proven useful to investigate - among other things - the foundations of statistical mechanics. Unfortunately, most states in the Hilbert space of a quantum many body…

Quantum Physics · Physics 2015-05-30 Alioscia Hamma , Siddhartha Santra , Paolo Zanardi

We consider a quaternionic quantum formalism for the description of quantum states and quantum dynamics. We prove that generalized quantum measurements on physical systems in quaternionic quantum theory can be simulated by usual quantum…

Quantum Physics · Physics 2015-07-29 Matthew A. Graydon