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We investigate the splitting probability of a monitored continuous-time quantum walk with two targets and show that, in stark contrast to a classical random walk, it exhibits a nonanalytic, phase-transition-like behavior controlled by the…

Statistical Mechanics · Physics 2026-01-23 Prashant Singh , David A. Kessler , Eli Barkai

There are two distinct perspectives on the quantum time-of-arrival: one can ask for the probability that a particle is found at the detector at a given time, regardless of whether it was previously detected, or for the probability that the…

Quantum Physics · Physics 2026-03-31 Mafalda Pinto Couto , Lorenzo Maccone , Lorenzo Catani , Simone Roncallo

In its simplest form, decoherence occurs when a quantum state is entangled with a second state, but the results of measurements made on the second state are not accessible. As the second state has effectively "measured" the first, in this…

Quantum Physics · Physics 2017-05-02 Samuel P. Nolan , Simon A. Haine

We present a detailed study of scattering by an amplitude-modulated potential barrier using three distinct physical frameworks: quantum, classical, and semiclassical. Classical physics gives bounds on the energy and momentum of the…

Quantum walks (QWs) represent pillars of quantum dynamics and information processing. They provide a powerful framework for simulating quantum transport, designing search algorithms, and enabling universal quantum computation. Several…

Quantum Physics · Physics 2026-01-30 E. Stefanutti , J. Philipps , J. Buetow , A. Guidara , M. Nuvoli , A. Chiuri , L. Sansoni

We address the relation between quantum metrological resolution and coherence. We examine this dependence in two manners: we develop a quantum Wiener-Kintchine theorem for a suitable model of quantum ruler, and we compute the Fisher…

Quantum Physics · Physics 2021-10-27 Laura Ares , Alfredo Luis

Quantum metrology concerns improving the estimation of an unknown parameter using an optimal measurement scheme on the quantum system. More the optimality of the measurement, the better will be the improvement in sensing the value of the…

Quantum Physics · Physics 2025-07-30 H. S. Karthik

The goal of quantum metrology is to improve measurements' sensitivities by harnessing quantum resources. Metrologists often aim to maximize the quantum Fisher information, which bounds the measurement setup's sensitivity. In studies of…

Quantum walks are roughly analogous to classical random walks, and like classical walks they have been used to find new (quantum) algorithms. When studying the behavior of large graphs or combinations of graphs it is useful to find the…

Quantum Physics · Physics 2015-10-28 Seth S. Cottrell

A {\it completed} scattering of a particle on a static one-dimensional (1D) potential barrier is a combined quantum process to consist from two elementary sub-processes (transmission and reflection) evolved coherently at all stages of…

Quantum Physics · Physics 2007-05-23 N L Chuprikov

Variational quantum algorithms are promising tools for near-term quantum computers as their shallow circuits are robust to experimental imperfections. Their practical applicability, however, strongly depends on how many times their circuits…

Quantum Physics · Physics 2021-09-13 Barnaby van Straaten , Bálint Koczor

The role of classical noise in quantum walks (QW) on integers is investigated in the form of discrete dichotomic random variable affecting its reshuffling matrix parametrized as a SU2)/U(1) coset element. Analysis in terms of quantum…

Quantum Physics · Physics 2015-06-05 D. Ellinas , A. J. Bracken , I. Smyrnakis

The discrete time quantum walk which is a quantum counterpart of random walk plays important roles in the theory of quantum information theory. In the present paper, we focus on discrete time quantum walks viewed as quantization of random…

Quantum Physics · Physics 2013-12-13 Yusuke Ide , Norio Konno , Etsuo Segawa

Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing…

Quantum Physics · Physics 2010-12-10 Godfrey Leung , Paul Knott , Joe Bailey , Viv Kendon

The quantum walk is the quantum analogue of the well-known random walk, which forms the basis for models and applications in many realms of science. Its properties are markedly different from the classical counterpart and might lead to…

When impurity and phonon scattering coexist, the Boltzmann equation has been solved accurately for nonlinear electron transport in a quantum wire. Based on the calculated non-equilibrium distribution of electrons in momentum space, the…

Strongly Correlated Electrons · Physics 2015-05-18 Danhong Huang , Godfrey Gumbs

We apply a discrete quantum walk from a quantum particle on a discrete quantum spacetime from loop quantum gravity and show that the related Entanglement Entropy can drive a entropic force. We apply this concepts to propose a model of a…

High Energy Physics - Theory · Physics 2017-06-19 M. M. Amaral , R. Aschheim , Klee Irwin

We consider quantum walks defined on arbitrary infinite graphs, parameterized by a family of scattering matrices attached to the vertices. Multiplying each scattering matrix by an i.i.d. random phase, we obtain a random scattering quantum…

Mathematical Physics · Physics 2026-02-16 Alain Joye , Andreas Schaefer , Simone Warzel

We propose an experimentally accessible scheme to determine lower bounds on the quantum Fisher information (QFI), which ascertains multipartite entanglement or usefulness for quantum metrology. The scheme is based on comparing the…

Quantum Physics · Physics 2016-03-14 Florian Fröwis , Pavel Sekatski , Wolfgang Dür

Quantum Fisher information is a central quantity in quantum metrology. We discuss an alternative representation of quantum Fisher information for unitary parametrization processes. The highlight of this representation is that all…

Quantum Physics · Physics 2015-02-25 Jing Liu , Xiaoxing Jing , Xiaoguang Wang