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For the quantum kicked top we study numerically the distribution of Hilbert-space vectors evolving in the presence of a small random perturbation. For an initial coherent state centered in a chaotic region of the classical dynamics, the…

chao-dyn · Physics 2009-10-22 Ruediger Schack , Giacomo M. D'Ariano , Carlton M. Caves

Quantum speed limits provide ultimate bounds on the time required to transform one quantum state into another. Here, we extend the notion of quantum speed limits to collections of quantum states, investigating the time for converting a…

Quantum Physics · Physics 2024-04-10 Moein Naseri , Chiara Macchiavello , Dagmar Bruß , Paweł Horodecki , Alexander Streltsov

In ordinary, non-relativistic, quantum physics, time enters only as a parameter and not as an observable: a state of a physical system is specified at a given time and then evolved according to the prescribed dynamics. While the state can,…

Quantum Physics · Physics 2013-02-13 Joseph Fitzsimons , Jonathan Jones , Vlatko Vedral

A cluster state cannot be a unique ground state of a two-body interacting Hamiltonian. Here, we propose the creation of a cluster state of logical qubits encoded in spin-1/2 particles by adiabatically weakening two-body interactions. The…

Quantum Physics · Physics 2014-10-30 Thi Ha Kyaw , Ying Li , Leong Chuan Kwek

We study the estimation of the overlap between two unknown pure quantum states of a finite dimensional system, given $M$ and $N$ copies of each type. This is a fundamental primitive in quantum information processing that is commonly…

Quantum systems are viewed as emergent systems from the fundamental degrees of freedom. The laws and rules of quantum mechanics are understood as an effective description, valid for the emergent systems and specially useful to handle…

Mathematical Physics · Physics 2025-11-26 Ricardo Gallego Torromé

Bell's theorem states that Local Hidden Variables (LHVs) cannot fully explain the statistics of measurements on some entangled quantum states. It is natural to ask how much supplementary classical communication would be needed to simulate…

Quantum Physics · Physics 2023-10-25 Peter Sidajaya , Aloysius Dewen Lim , Baichu Yu , Valerio Scarani

Steerability is a characteristic nonlocal trait of quantum states lying in between entanglement and Bell nonlocality. A given quantum state is considered to be steerable if it violates a suitably chosen steering inequality. A quantum state…

This PHD thesis is concerned with uncertainty relations in quantum probability theory, state estimation in quantum stochastics, and natural bundles in differential geometry. After some comments on the nature and necessity of decoherence in…

Differential Geometry · Mathematics 2010-11-15 Bas Janssens

Contrary to general relativity, quantum theory treats space and time in fundamentally different ways. In particular, while joint probabilities associated with spacelike separated measurements are defined in terms of the Born rule, joint…

Quantum Physics · Physics 2026-01-13 James Fullwood , Zhihao Ma , Zhen Wu

We investigate the question of unitarity of evolution between hypersurfaces in quantum field theory in curved spacetime from the perspective of the general boundary formulation. Unitarity thus means unitarity of the quantum operator that…

High Energy Physics - Theory · Physics 2011-08-25 Daniele Colosi , Robert Oeckl

A non-ergodic quantum state of a many body system is in general random as well as multi-parametric, former due to a lack of exact information due to complexity and latter reflecting its varied behavior in different parts of the Hilbert…

Quantum Physics · Physics 2023-06-21 Devanshu Shekhar , Pragya Shukla

We introduce a 'uniform tension-reduction' (UTR) model, which allows to represent the probabilities associated with an arbitrary measurement situation and use it to explain the emergence of quantum probabilities (the Born rule) as 'uniform'…

Quantum Physics · Physics 2015-09-17 Diederik Aerts , Massimiliano Sassoli de Bianchi

We construct a class of systems for which quantum dynamics can be expanded around a mean field approximation with essentially classical content. The modulus of the quantum overlap of mean field states naturally introduces a classical…

Mutually unbiased bases (MUBs) play a key role in many protocols in quantum science, such as quantum key distribution. However, defining MUBs for arbitrary high-dimensional systems is theoretically difficult, and measurements in such bases…

Quantum Physics · Physics 2013-04-03 D. Giovannini , J. Romero , J. Leach , A. Dudley , A. Forbes , M. J. Padgett

A possible solution to the problem of providing a spacetime description of the transmission of signals for quantum entangled states is obtained by using a bimetric spacetime structure, in which quantum entanglement measurements alter the…

Quantum Physics · Physics 2014-11-18 J. W. Moffat

We use a one-dimensional model system to compare the predictions of two different 'yardsticks' to compute the position of a particle from its quantum field theoretical state. Based on the first yardstick (defined by the Newton-Wigner…

Quantum Physics · Physics 2015-06-15 R. E. Wagner , M. R. Ware , E. V. Stefanovich , Q. Su , R. Grobe

Quantum metrology seeks to push the boundaries of measurement precision by harnessing quantum phenomena. Conventional methods often rely on maximally entangled resources, with states that are usually challenging to produce and sustain in…

Quantum Physics · Physics 2026-02-23 Unathi Skosana , Byron Alexander , Changhyoup Lee , Mark Tame

The evolution of an open system is usually associated with the interaction of the system with an environment. A new method to study the open-type system evolution of a qubit (two-level atom) state is established. This evolution is…

As quantum computers and simulators begin to produce results that cannot be verified classically, it becomes imperative to develop a variety of tools to detect and diagnose experimental errors on these devices. While state or process…

Quantum Physics · Physics 2022-12-22 Alaina M. Green , Tanmoy Pandit , C. Huerta Alderete , Norbert M. Linke , Raam Uzdin