scholarly journals The quantum beam splitter revisited without a vacuum state

2022 ◽  
Vol 19 (1 Jan-Jun) ◽  
Author(s):  
Alexander Nahmad ◽  
Damian P San-Roman-Alerigi ◽  
Edna Magdalena Hernández González ◽  
Erick Barrios ◽  
Gustavo Armendariz Peña ◽  
...  
Keyword(s):  
Beam Splitter ◽  
Single Photon ◽  
Vacuum State ◽  
Quantum States ◽  
Wave Functions ◽  
Quantum Interferometer ◽  
Quantum Wave ◽  
Photon States

In this article we explain in a new light two fundamental concepts ofquantum optics, the quantum beam splitter and the quantum interferometer, in termsof two state quantum wave functions. This method is consistent with the concept ofentanglement, and hence the algebra needed to describe them is reduced to additionsand products of the components of the quantum states. Furthermore, under thepremises of this method it is possible to study quantum states of greater complexity,like those arising from the addition and products of single photon states.

scholarly journals Collapse dynamics and Hilbert-space stochastic processes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Daniele Bajoni ◽  
Oreste Nicrosini ◽  
Alberto Rimini ◽  
Simone Rodini
Keyword(s):  
Hilbert Space ◽  
Beam Splitter ◽  
Measurement Problem ◽  
Single Photon ◽  
Numerical Approach ◽  
Quantum States ◽  
Photon Detector ◽  
State Vector Reduction ◽  
Collapse Models ◽  
Physical Features

AbstractSpontaneous collapse models of state vector reduction represent a possible solution to the quantum measurement problem. In the present paper we focus our attention on the Ghirardi–Rimini–Weber (GRW) theory and the corresponding continuous localisation models in the form of a Brownian-driven motion in Hilbert space. We consider experimental setups in which a single photon hits a beam splitter and is subsequently detected by photon detector(s), generating a superposition of photon-detector quantum states. Through a numerical approach we study the dependence of collapse times on the physical features of the superposition generated, including also the effect of a finite reaction time of the measuring apparatus. We find that collapse dynamics is sensitive to the number of detectors and the physical properties of the photon-detector quantum states superposition.

Quantum Theory

2017 ◽  
Author(s):  
Frank S. Levin
Keyword(s):  
Quantum Mechanics ◽  
Quantum Theory ◽  
Uncertainty Principle ◽  
Quantum Spin ◽  
Quantum States ◽  
Wave Functions ◽  
Symbolic Representations ◽  
Quantum Numbers ◽  
The Subject ◽  
Heisenberg's Uncertainty Principle

The subject of Chapter 8 is the fundamental principles of quantum theory, the abstract extension of quantum mechanics. Two of the entities explored are kets and operators, with kets being representations of quantum states as well as a source of wave functions. The quantum box and quantum spin kets are specified, as are the quantum numbers that identify them. Operators are introduced and defined in part as the symbolic representations of observable quantities such as position, momentum and quantum spin. Eigenvalues and eigenkets are defined and discussed, with the former identified as the possible outcomes of a measurement. Bras, the counterpart to kets, are introduced as the means of forming probability amplitudes from kets. Products of operators are examined, as is their role underpinning Heisenberg’s Uncertainty Principle. A variety of symbol manipulations are presented. How measurements are believed to collapse linear superpositions to one term of the sum is explored.

scholarly journals Scattering in Terms of Bohmian Conditional Wave Functions for Scenarios with Non-Commuting Energy and Momentum Operators

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 408
Author(s):  
Matteo Villani ◽  
Guillermo Albareda ◽  
Carlos Destefani ◽  
Xavier Cartoixà ◽  
Xavier Oriols
Keyword(s):  
Single Particle ◽  
Degrees Of Freedom ◽  
Single Photon ◽  
Open Quantum Systems ◽  
Wave Functions ◽  
Practical Application ◽  
Light Matter Interaction ◽  
Pure States ◽  
Energy And Momentum ◽  
Full Quantum

Without access to the full quantum state, modeling quantum transport in mesoscopic systems requires dealing with a limited number of degrees of freedom. In this work, we analyze the possibility of modeling the perturbation induced by non-simulated degrees of freedom on the simulated ones as a transition between single-particle pure states. First, we show that Bohmian conditional wave functions (BCWFs) allow for a rigorous discussion of the dynamics of electrons inside open quantum systems in terms of single-particle time-dependent pure states, either under Markovian or non-Markovian conditions. Second, we discuss the practical application of the method for modeling light–matter interaction phenomena in a resonant tunneling device, where a single photon interacts with a single electron. Third, we emphasize the importance of interpreting such a scattering mechanism as a transition between initial and final single-particle BCWF with well-defined central energies (rather than with well-defined central momenta).

scholarly journals Non-Gaussianity of quantum states: An experimental test on single-photon-added coherent states

2010 ◽  
Vol 82 (6) ◽  
Author(s):  
Marco Barbieri ◽  
Nicolò Spagnolo ◽  
Marco G. Genoni ◽  
Franck Ferreyrol ◽  
Rémi Blandino ◽  
...  
Keyword(s):  
Experimental Test ◽  
Coherent States ◽  
Single Photon ◽  
Quantum States

scholarly journals Quantum flux and reverse engineering of quantum wave functions

2013 ◽  
Vol 102 (6) ◽  
pp. 60005 ◽  
Author(s):  
D. J. Mason ◽  
M. F. Borunda ◽  
E. J. Heller
Keyword(s):  
Reverse Engineering ◽  
Wave Functions ◽  
Quantum Flux ◽  
Quantum Wave

Homodyne-like detection scheme based on photon-number-resolving detectors

2017 ◽  
Vol 15 (08) ◽  
pp. 1740016 ◽  
Author(s):  
Alessia Allevi ◽  
Matteo Bina ◽  
Stefano Olivares ◽  
Maria Bondani
Keyword(s):  
Coherent States ◽  
Beam Splitter ◽  
Photon Number ◽  
Local Oscillator ◽  
Quantum States ◽  
Homodyne Detection ◽  
Detection Scheme ◽  
Light Signals ◽  
The Difference ◽  
Signal Field

Homodyne detection is the most effective detection scheme employed in quantum optics to characterize quantum states. It is based on mixing at a beam splitter the signal to be measured with a coherent state, called the “local oscillator,” and on evaluating the difference of the photocurrents of two photodiodes measuring the outputs of the beam splitter. If the local oscillator is much more intense than the field to be measured, the homodyne signal is proportional to the signal-field quadratures. If the local oscillator is less intense, the photodiodes can be replaced with photon-number-resolving detectors, which have a smaller dynamics but can measure the light statistics. The resulting new homodyne-like detector acquires a hybrid nature, being it capable of yielding information on both the particle-like (statistics) and wave-like (phase) properties of light signals. The scheme has been tested in the measurement of the quadratures of coherent states, bracket states and phase-averaged coherent states at different intensities of the local oscillator.

scholarly journals Quantum Filtering Equations for a System Driven by Nonclassical Fields

2018 ◽  
Vol 25 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Anita Da̧browska
Keyword(s):  
Quantum System ◽  
Coherent States ◽  
Single Photon ◽  
Photon Counting ◽  
Stochastic Evolution ◽  
Input Output ◽  
Nonclassical States ◽  
Cascade System ◽  
Unitary Evolution ◽  
Photon States

Using Gardiner and Collet’s input-output model and the concept of cascade system, we determine the filtering equation for a quantum system driven by light in some specific nonclassical states. The quantum system and electromagnetic field are described by making use of quantum stochastic unitary evolution. We consider two examples of the nonclassical states of field: a combination of vacuum and single photon states and a mixture of two coherent states. The stochastic evolution conditioned on the results of the photon counting and quadrature measurements is described.

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