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We present a method for quantum state tomography that enables the efficient estimation, with fixed precision, of any of the matrix elements of the density matrix of a state, provided that the states from the basis in which the matrix is…

Quantum Physics · Physics 2015-06-12 Ariel Bendersky , Juan Pablo Paz

Effective quantum cosmology is formulated with a realistic global internal time given by the electric vector potential. New possibilities for the quantum behavior of space-time are found, and the high-density regime is shown to be very…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Stephon Alexander , Martin Bojowald , Antonino Marciano , David Simpson

Electron capture processes are important in the search for new physics. In this context, a high capture rate is desired. We investigate the possibility of enhancing the electron capture rate by irradiating laser beam to ''atom''. The…

High Energy Physics - Phenomenology · Physics 2008-11-26 Takaaki Nomura , Joe Sato , Takashi Shimomura

We present a polynomial-time quantum algorithm for obtaining the energy spectrum of a physical system, i.e. the differences between the eigenvalues of the system's Hamiltonian, provided that the spectrum of interest contains at most a…

Quantum Physics · Physics 2012-06-22 Hefeng Wang , S. Ashhab , Franco Nori

We use quantum energy teleportation in the light-matter interaction as an operational means to create quantum field states that violate energy conditions and have negative local stress-energy densities. We show that the protocol is optimal…

Quantum Physics · Physics 2025-03-20 Nicholas Funai , Eduardo Martin-Martinez

The current density for a freely evolving state without negative momentum components can temporarily be negative. The operational arrival time distribution, defined by the absorption rate of an ideal detector, is calculated for a model…

Quantum Physics · Physics 2009-10-31 J. G. Muga , J. P. Palao , C. R. Leavens

A random matrix theory approach is applied in order to analyze the localization properties of local spectral density for a generic system of coupled quantum states with strong static imperfection in the unperturbed energy levels. The system…

Quantum Physics · Physics 2009-11-07 V. S. Starovoitov

Probing optical excitations with nanometer resolution is important for understanding their dynamics and interactions down to the atomic scale. Electron microscopes currently offer the unparalleled ability of rendering spatially-resolved…

Quantum Physics · Physics 2020-07-16 Valerio Di Giulio , Mathieu Kociak , F. Javier García de Abajo

We investigate quantum radiation reaction in laser-electron interactions across different energy and intensity regimes. Using a fully quantum approach which also accounts exactly for the effect of the strong laser pulse on the electron…

High Energy Physics - Phenomenology · Physics 2016-03-17 Victor Dinu , Chris Harvey , Anton Ilderton , Mattias Marklund , Greger Torgrimsson

We generalize effective energy variational techniques to study appropriately quantized solitonic field configurations. Our approach rests on collective quantization ideas and is specifically designed for the numerical evaluation of soliton…

High Energy Physics - Theory · Physics 2008-11-26 Sergei V. Bashinsky

A theoretical description of local absorption is proposed in order to investigate spectral variations on a length scale comparable with the extension of the relevant quantum states. A general formulation is derived within the density-matrix…

Materials Science · Physics 2009-10-31 O. Mauritz , G. Goldoni , F. Rossi , E. Molinari

We present quantum algorithms for the estimation of n-time correlation functions, the local and non-local density of states, and dynamical linear response functions. These algorithms are all based on block-encodings - a versatile technique…

Quantum Physics · Physics 2020-08-19 Patrick Rall

In quantum field theory, coherent states can be created that have negative energy density, meaning it is below that of empty space, the free quantum vacuum. If no restrictions existed regarding the concentration and permanence of negative…

Quantum Physics · Physics 2026-04-01 G. Jordan Maclay , Eric W. Davis

The study addresses the quantum spreading of a localized stationary flow of high energy particles. Results demonstrate that as particle energy increases, the spreading speed of the particle wave packet diminishes rapidly. Concurrently,…

High Energy Physics - Phenomenology · Physics 2023-10-17 N. F. Shul'ga , S. N. Shulga

The ultimate electric and magnetic energy densities that can be attained by bandlimited electromagnetic pulses in free space are calculated using an ab initio quantized treatment, and the quantum states of electromagnetic fields that…

Quantum Physics · Physics 2008-03-07 Mankei Tsang

Kernel density estimation is a convenient way to estimate the probability density of a distribution given the sample of data points. However, it has certain drawbacks: proper description of the density using narrow kernels needs large data…

Data Analysis, Statistics and Probability · Physics 2015-02-27 Anton Poluektov

The standard experimental techniques usually adopted in the study of the behaviour of ultracold atoms in optical lattices involve extracting the atom density profile from absorption images of the atomic sample after trap release. Quantum…

Quantum Physics · Physics 2009-11-13 S. Anderloni , F. Benatti , R. Floreanini , A. Trombettoni

Entanglement in high energy and and nuclear reactions is receiving great attention. A proper description of these reactions uses density matrices, and the express of entanglement in terms of {\it separability}. Quantum tomography bypasses…

High Energy Physics - Phenomenology · Physics 2019-10-15 John C. Martens , John P. Ralston , Daniel Tapia Takaki

Quantum metrology utilizes entanglement for improving the sensitivity of measurements. Up to now the focus has been on the measurement of just one out of two non-commuting observables. Here we demonstrate a laser interferometer that…

The experimental evaluation of many quantum mechanical quantities requires the estimation of several directly measurable observables, such as local observables. Due to the necessity to repeat experiments on individual quantum systems in…

Quantum Physics · Physics 2024-06-10 Ruidi Zhu , Ciara Pike-Burke , Florian Mintert