scholarly journals Quantum Darwinism in a Composite System: Objectivity versus Classicality

Entropy ◽  
2021 ◽  
Vol 23 (8) ◽  
pp. 995
Author(s):  
Barış Çakmak ◽  
Özgür E. Müstecaplıoğlu ◽  
Mauro Paternostro ◽  
Bassano Vacchini ◽  
Steve Campbell
Keyword(s):  
Hilbert Space ◽  
Quantum System ◽  
Quantum Discord ◽  
Composite System ◽  
Analytical Expression ◽  
Composite Systems ◽  
Composite Quantum System ◽  
Qubit System ◽  
Quantum Darwinism ◽  
Decoherence Free Subspace

We investigate the implications of quantum Darwinism in a composite quantum system with interacting constituents exhibiting a decoherence-free subspace. We consider a two-qubit system coupled to an N-qubit environment via a dephasing interaction. For excitation preserving interactions between the system qubits, an analytical expression for the dynamics is obtained. It demonstrates that part of the system Hilbert space redundantly proliferates its information to the environment, while the remaining subspace is decoupled and preserves clear non-classical signatures. For measurements performed on the system, we establish that a non-zero quantum discord is shared between the composite system and the environment, thus violating the conditions of strong Darwinism. However, due to the asymmetry of quantum discord, the information shared with the environment is completely classical for measurements performed on the environment. Our results imply a dichotomy between objectivity and classicality that emerges when considering composite systems.

scholarly journals DECOHERENCE IN COMPOSITE QUANTUM OPEN SYSTEMS: THE EFFECTIVENESS OF UNSTABLE DEGREES OF FREEDOM

2006 ◽  
Vol 20 (20) ◽  
pp. 2951-2976 ◽  
Author(s):  
FERNANDO C. LOMBARDO ◽  
PAULA I. VILLAR
Keyword(s):  
Harmonic Oscillator ◽  
Quantum System ◽  
Degrees Of Freedom ◽  
Composite System ◽  
Open Systems ◽  
External Environment ◽  
Degree Of Freedom ◽  
Quantum Open Systems ◽  
Composite Quantum System

The effect induced by an environment on a composite quantum system is studied. The model considers the composite system as comprised by a subsystem A coupled to a subsystem B which is also coupled to an external environment. We studied all possible four combinations of subsystems A and B made up with a harmonic oscillator and an upside down oscillator. We analyzed the decoherence suffered by subsystem A due to an effective environment composed by subsystem B and the external reservoir. In all the cases we found that subsystem A decoheres even though it interacts with the environment only through its sole coupling to B. However, the effectiveness of the diffusion depends on the unstable nature of subsystem A and B. Therefore, the role of this degree of freedom in the effective environment is analyzed in detail.

scholarly journals Quantum system compression: A Hamiltonian guided walk through Hilbert space

2021 ◽  
Vol 103 (1) ◽  
Author(s):  
Robert L. Kosut ◽  
Tak-San Ho ◽  
Herschel Rabitz
Keyword(s):  
Hilbert Space ◽  
Quantum System

scholarly journals Reading a Qubit Quantum State with a Quantum Meter: Time Unfolding of Quantum Darwinism and Quantum Information Flux

2019 ◽  
Vol 26 (04) ◽  
pp. 1950023
Author(s):  
Salvatore Lorenzo ◽  
Mauro Paternostro ◽  
G. Massimo Palma
Keyword(s):  
Quantum Information ◽  
Harmonic Oscillator ◽  
Quantum System ◽  
Quantum State ◽  
Common Theme ◽  
Quantum Harmonic Oscillator ◽  
Collision Model ◽  
Single Qubit ◽  
Quantum Darwinism

Quantum non-Markovianity and quantum Darwinism are two phenomena linked by a common theme: the flux of quantum information between a quantum system and the quantum environment it interacts with. In this work, making use of a quantum collision model, a formalism initiated by Sudarshan and his school, we will analyse the efficiency with which the information about a single qubit gained by a quantum harmonic oscillator, acting as a meter, is transferred to a bosonic environment. We will show how, in some regimes, such quantum information flux is inefficient, leading to the simultaneous emergence of non-Markovian and non-darwinistic behaviours.

The Analysis and Synthesis of Vibrating Systems

1954 ◽  
Vol 58 (526) ◽  
pp. 703-719 ◽  
Author(s):  
R. E. D. Bishop
Keyword(s):  
Composite System ◽  
Frequency Equation ◽  
Computational Effort ◽  
Analytical Treatment ◽  
Principal Mode ◽  
Oscillatory Systems ◽  
Composite Systems ◽  
Analysis And Synthesis ◽  
Simple Systems ◽  
Vibrating Systems

SummaryComplicated oscillatory systems may be broken down into component “ sub-systems ” for the purpose of vibration analysis. These will generally submit more readily to analytical treatment. After an introduction to the concept of receptance, the principles underlying this form of analysis are reviewed.The dynamical properties of simple systems (in the form of their receptances) may be tabulated. By this means the properties of a complicated system may be found by first analysing it into convenient sub-systems and then extracting the properties of the latter from a suitable table. A catalogue of this sort is given for the particular case of conservative torsional systems with finite freedom.The properties of the composite system which may be readily found in this way are (i) its receptances and (ii) its frequency equation. Tables are given of expressions for these in terms of the receptances of the component sub-systems. All of the tables may easily be extended. The tabulated receptances may also be used for determining relative displacements during free vibration in any principal mode.A method of presenting information on the vibration characteristics of machinery, which is effectively due to Carter, is illustrated by means of an example. More general adoption by manufacturers of this method (which requires no more computational effort than must normally be made) would lead to enormous savings of labour in calculating natural frequencies of composite systems.

Effectiveness of Non-Markovian Methods for Quantum Discord Dynamics of Non-coupled Two-Qubit System

2018 ◽  
Vol 70 (3) ◽  
pp. 268 ◽  
Author(s):  
Yong-Gang Huang ◽  
Xiao-Yun Wang ◽  
Xue-Xian Yang ◽  
Ke Deng ◽  
Jin-Zhang Peng ◽  
...  
Keyword(s):  
Quantum Discord ◽  
Qubit System

scholarly journals Delayed-choice Measurement and Temporal Nonlocality

2001 ◽  
Vol 56 (1-2) ◽  
pp. 202-204 ◽  
Author(s):  
Ilki Kim ◽  
Günter Mahler
Keyword(s):  
Quantum Mechanics ◽  
Quantum System ◽  
Direct Observation ◽  
Bell Inequality ◽  
Network Dynamics ◽  
Consistent Histories ◽  
Discrete Parameter ◽  
Delayed Choice ◽  
Composite Quantum System ◽  
Non Locality

AbstractWe study for a composite quantum system with a quantum Turing architecture the temporal non-locality of quantum mechanics by using the temporal Bell inequality, which will be derived for a discretized network dynamics by identifying the subsystem indices with (discrete) parameter time. However, the direct “observation” of the quantum system will lead to no violation of the temporal Bell inequality and to consistent histories of any subsystem. Its violation can be demonstrated, though, for a delayedchoice measurement

Measurement of quantum correlation by Frobenius norm in non-Markovian system

2018 ◽  
Vol 16 (03) ◽  
pp. 1850022 ◽  
Author(s):  
Juju Hu ◽  
Shuqin Liu ◽  
Yinghua Ji
Keyword(s):  
Density Matrix ◽  
Quantum System ◽  
Quantum Correlation ◽  
Quantum Discord ◽  
Frobenius Norm ◽  
Easy Method ◽  
Test Matrix ◽  
Research Results ◽  
Bipartite State ◽  
Markovian System

In order to measure the quantum correlation of a bipartite state quickly, an easy method is to construct a test matrix through the commutations among the blocks of its density matrix. Then, the Frobenius norm of the test matrix can be used to measure the quantum correlation. In this paper, we apply the measurement by Frobenius norm ([Formula: see text] to the dynamics evolution of the non-Markovian quantum system and compare it with the typical quantum discord ([Formula: see text] proposed by Ollivier and Zurek. The research results show that [Formula: see text] can indeed measure the quantum correlation of a bipartite state as same as [Formula: see text]. Further studies find that there are still differences between the two measurements: in some regions, when [Formula: see text] is zero, [Formula: see text] is not zero. It indicates that [Formula: see text] is more detailed than [Formula: see text] to measure quantum correlation of a bipartite state.

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