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A scheme for optimal Gaussian cloning of optical coherent states is proposed and experimentally demonstrated. Its optical realization is based entirely on simple linear optical elements and homodyne detection. The optimality of the…

Quantum Physics · Physics 2009-11-11 Ulrik L. Andersen , Vincent Josse , Gerd Leuchs

In this paper, we provide an algorithm and general framework for the simulation of photons passing through linear optical interferometers. Given $n$ photons at the input of an $m$-mode interferometer, our algorithm computes the…

Quantum Physics · Physics 2023-08-04 Nicolas Heurtel , Shane Mansfield , Jean Senellart , Benoît Valiron

Recently, a generalization of the standard optical multiport was proposed [Phys. Rev. A 93, 043845 (2016)]. These directionally unbiased multiports allow photons to reverse direction and exit backwards from the input port, providing a…

Quantum Physics · Physics 2017-04-12 David S. Simon , Casey A. Fitzpatrick , Shuto Osawa , Alexander V. Sergienko

The decomposition or approximation of a linear operator on a matrix space as a sum of Kronecker products plays an important role in matrix equations and low-rank modeling. The approximation problem in Frobenius norm admits a well-known…

Optimization and Control · Mathematics 2023-12-08 Mareike Dressler , André Uschmajew , Venkat Chandrasekaran

We propose a hybrid quantum-classical approximate optimization algorithm for photonic quantum computing, specifically tailored for addressing continuous-variable optimization problems. Inspired by counterdiabatic protocols, our algorithm…

Quantum Physics · Physics 2024-10-03 Pranav Chandarana , Koushik Paul , Mikel Garcia-de-Andoin , Yue Ban , Mikel Sanz , Xi Chen

Continuous-variables (CV) quantum optics is a natural formalism for neural networks (NNs) due to its ability to reproduce the information processing of such trainable interconnected systems. In quantum optics, Gaussian operators induce…

Quantum Physics · Physics 2026-01-15 Todor Krasimirov-Ivanov , Alba Cervera-Lierta , Paolo Stornati , Federico Centrone

In this work, a novel method for using a set of electromagnetic quadrupole fields is presented to implement arbitrary unitary operators on a two-state quantum system of electrons. In addition to analytical derivations of the required…

Quantum Physics · Physics 2022-02-28 Stefan Löffler

Precise device characterization is a fundamental requirement for a large range of applications using photonic hardware, and constitutes a multi-parameter estimation problem. Estimates based on measurements using single photons or classical…

Quantum Physics · Physics 2023-08-24 Nana Liu , Hugo Cable

We suggest an efficient scheme for quantum computation with linear optical elements utilizing "linked" photon states. The linked states are designed according to the particular quantum circuit one wishes to process. Once a linked-state has…

Quantum Physics · Physics 2009-11-10 Nadav Yoran , Benni Reznik

Optical tweezers constitute pivotal tools in Atomic, Molecular, and Optical(AMO) physics, facilitating precise trapping and manipulation of individual atoms and molecules. This process affords the capability to generate desired geometries…

Atomic Physics · Physics 2024-01-11 Yongwoong Lee , Eunmi Chae

We attempt the use of a unitary operator to approximate the lattice Boltzmann collision operator. We use a modified amplitude encoding to bypass the renormalization that would have required classical processing at every step (thus eroding…

Quantum Physics · Physics 2026-01-08 Wael Itani , Katepalli R. Sreenivasan

Linear optics underpins tests of fundamental quantum mechanics and computer science, as well as quantum technologies. Here we experimentally demonstrate the longstanding goal of a single reprogrammable optical circuit that is sufficient to…

We derive an exact equation of motion for the reduced density matrices of individual subsystems of quantum many-body systems of any lattice dimension and arbitrary system size. Our projection operator based theory yields a highly efficient…

Quantum Physics · Physics 2014-06-13 Peter Degenfeld-Schonburg , Michael J. Hartmann

We propose an approach to optical quantum computation in which a deterministic entangling quantum gate may be performed using, on average, a few hundred coherently interacting optical elements (beamsplitters, phase shifters, single photon…

Quantum Physics · Physics 2009-11-10 Michael A. Nielsen

Knill, Laflamme, and Milburn [Nature 409, 46 (2001)] have shown that quantum logic operations can be performed using linear optical elements and additional ancilla photons. Their approach is probabilistic in the sense that the logic devices…

Quantum Physics · Physics 2009-11-07 J. D. Franson , M. M. Donegan , M. J. Fitch , B. C. Jacobs , T. B. Pittman

The working principles of linear optical quantum computing are based on photodetection, namely, projective measurements. The use of photodetection can provide efficient nonlinear interactions between photons at the single-photon level,…

Quantum Physics · Physics 2010-04-09 Hwang Lee , Pieter Kok , Colin P. Williams , Jonathan P. Dowling

Maximum likelihood iteration is one of the most commonly used reconstruction algorithms in quantum tomography. The main appeal of the method is that it is easy to implement and that it converges reliably to a physically meaningful density…

Quantum Physics · Physics 2025-08-21 Florian Oberender

We augment the time-linear formulation of the Kadanoff-Baym equations for systems of interacting electrons and quantized phonons or photons with the $G\widetilde{W}$ approximation, the Coulomb interaction $\widetilde{W}$ being dynamically…

Other Condensed Matter · Physics 2022-12-14 Yaroslav Pavlyukh , Enrico Perfetto , Gianluca Stefanucci

We present a unified framework to construct well-posed formulations for large classes of linear operator equations including elliptic, parabolic and hyperbolic partial differential equations. This general approach incorporates known weak…

Numerical Analysis · Mathematics 2025-08-08 Moritz Feuerle , Richard Löscher , Olaf Steinbach , Karsten Urban

This thesis contains contributions to the theory of quantum computation. We first define a new method to efficiently approximate special unitary operators. Specifically, given a special unitary U and a precision {\epsilon} > 0, we show how…

Quantum Physics · Physics 2017-02-17 Neil J. Ross