scholarly journals Coupling modifies the quantum fluctuations of entangled oscillators

2021 ◽  
Author(s):  
Roberto Baginski Batista Santos ◽  
Vinicius de Souza Ferreira Lisboa
Keyword(s):  
Coupled Oscillators ◽  
Quantum Fluctuations ◽  
Quantum Systems ◽  
Transfer Mechanism ◽  
The Other ◽  
Precision Measurements ◽  
Uncertainty Product

Abstract Coupled oscillators are among the simplest composite quantum systems in which the interplay of entanglement and interaction may be explored. We examine the effects of coupling on the quantum fluctuations of the coordinates and momenta of the oscillators in a single-excitation entangled Bell-like state. We discover that coupling acts as a mechanism for noise transfer between one pair of coordinate and momentum and another. Through this noise transfer mechanism, the uncertainty product is lowered, on average, relatively to its non-coupled level for one pair of coordinate and momentum and it is enhanced for the other pair. This novel mechanism for noise transfer may be explored in precision measurements in entanglement-assisted sensing and metrology.

scholarly journals Multi-Bloch vector representation of the qutrit

2011 ◽  
Vol 11 (5&6) ◽  
pp. 361-373
Author(s):  
Pawel Kurzynski
Keyword(s):  
Quantum State ◽  
Quantum Systems ◽  
Quantum States ◽  
The Other ◽  
Two Dimensional ◽  
Bloch Vector ◽  
Vector Representation ◽  
Alternative Approach ◽  
Complete Set

An ability to describe quantum states directly by average values of measurement outcomes is provided by the Bloch vector. For an informationally complete set of measurements one can construct unique Bloch vector for any quantum state. However, not every Bloch vector corresponds to a quantum state. It seems that only for two-dimensional quantum systems it is easy to distinguish proper Bloch vectors from improper ones, i.e. the ones corresponding to quantum states from the other ones. I propose an alternative approach to the problem in which more than one vector is used. In particular, I show that a state of the qutrit can be described by the three qubit-like Bloch vectors.

DYNAMICS AND MODULATED CHAOS FOR TWO COUPLED OSCILLATORS

2004 ◽  
Vol 14 (01) ◽  
pp. 337-346 ◽  
Author(s):  
QINSHENG BI
Keyword(s):  
Coupled Oscillators ◽  
Dynamical Behavior ◽  
Period Doubling ◽  
Period Doubling Bifurcation ◽  
The Other ◽  
Van Der Pol ◽  
Parametrically Excited ◽  
Van Der Pol Oscillators ◽  
Period Doubling Bifurcations

The dynamical behavior of two coupled parametrically excited van der Pol oscillators is investigated in this paper. A special road to chaos is explored in detail. Period-doubling bifurcation associated with one of the frequencies of the system may be observed, the other frequency of the coupled oscillators plays a role in the evolution. It is found that one of the frequencies of the system contributes to the cascade of period-doubling bifurcations associated with the other frequency, which leads to a generalized modulated chaos.

scholarly journals STUDYING STRUCTURE OF ELECTROWEAK CORRECTIONS

1995 ◽  
Vol 10 (26) ◽  
pp. 3803-3815 ◽  
Author(s):  
ZENRŌ HIOKI
Keyword(s):  
Top Quark ◽  
Confidence Level ◽  
Born Approximation ◽  
Higgs Mass ◽  
New Physics ◽  
The Other ◽  
Precision Measurements ◽  
Quantum Corrections ◽  
Electroweak Theory ◽  
Weak Boson

Several different effects in electroweak quantum corrections are explored separately through the latest data on the weak-boson masses. The leading-log approximation, the improved-Born approximation and the nondecoupling top-quark effects are studied without depending on the recent CDF data about mt, and the results are given in a form independent, of the Higgs mass. On the other hand, the bosonic and the nondecoupling Higgs effects are examined by fully taking account of those CDF data. It is emphasized that future precision measurements of MW and mt are considerably significant not only for further studies of the electroweak theory at higher confidence level but also for new-physics searches beyond it.

scholarly journals Study of Superficial Layers Obtained by Selective Transfer in the Friction Couples

2017 ◽  
Vol 2 (6) ◽  
pp. 54
Author(s):  
Filip Ilie
Keyword(s):  
Superficial Layer ◽  
Transfer Mechanism ◽  
The Other ◽  
X Rays ◽  
Selective Transfer ◽  
Friction Couple ◽  
Material Transfer ◽  
Structure Defects ◽  
Wear Process ◽  
Friction Surfaces

In the friction process of two materials and in the presence of some proper lubricants, the wear process manifest itself as a material transfer from an element of the friction couple on the other, process specific to the selective transfer mechanism. The selective transfer can be sure achieved in a friction couple if there is a favorable energy, the relative movement and if in the friction area is a material made by copper and the lubricant is adequate (glycerin).The selective transfer mechanism is characterized by the physicochemical processes, which take place in the contact zones of the friction couples, and which to allow the selective transfer of some elements of the materials from a surface to the other, forming a thin superficial layer with the superior properties at wear and friction. This is a condition for any friction couple of high efficiently and a normal self-adjusting phenomena. The forming of this layer on the contact surfaces makes as fiction force to be reduced. It is in closely related to the structure formed by the selective transfer, between the metallic friction surfaces and with the properties these surface layers metallic. The most important parameters concerning the physical state of the superficial layers are micro-tensions, the structure and its modification on friction surfaces, the structure defects as well as the way of distribution of the additions and of the alloying elements from alloy. The purpose of the present paper is research these parameters by the structural analysis with X-rays, as the research method of the thin superficial layers.

scholarly journals Quantum Horn's lemma, finite heat baths, and the third law of thermodynamics

Quantum ◽  
2018 ◽  
Vol 2 ◽  
pp. 54 ◽  
Author(s):  
Jakob Scharlau ◽  
Markus P. Mueller
Keyword(s):  
Crucial Role ◽  
Heat Bath ◽  
Quantum Systems ◽  
The Other ◽  
State Transitions ◽  
Quantum Operations ◽  
The Third ◽  
Third Law Of Thermodynamics ◽  
Quantum Version ◽  
Third Law

Interactions of quantum systems with their environment play a crucial role in resource-theoretic approaches to thermodynamics in the microscopic regime. Here, we analyze the possible state transitions in the presence of "small" heat baths of bounded dimension and energy. We show that for operations on quantum systems with fully degenerate Hamiltonian (noisy operations), all possible state transitions can be realized exactly with a bath that is of the same size as the system or smaller, which proves a quantum version of Horn's lemma as conjectured by Bengtsson and Zyczkowski. On the other hand, if the system's Hamiltonian is not fully degenerate (thermal operations), we show that some possible transitions can only be performed with a heat bath that is unbounded in size and energy, which is an instance of the third law of thermodynamics. In both cases, we prove that quantum operations yield an advantage over classical ones for any given finite heat bath, by allowing a larger and more physically realistic set of state transitions.

scholarly journals Quantum Entropy and Complexity

2017 ◽  
Vol 24 (02) ◽  
pp. 1750005
Author(s):  
F. Benatti ◽  
S. Khabbazi Oskouei ◽  
A. Shafiei Deh Abad
Keyword(s):  
Dynamical Systems ◽  
Shannon Entropy ◽  
Kolmogorov Complexity ◽  
Quantum Systems ◽  
Quantum Spin ◽  
Spin Chains ◽  
The Other ◽  
Quantum Entropy ◽  
Quantum Spin Chains ◽  
Quantum Complexity

We study the relations between the recently proposed machine-independent quantum complexity of P. Gacs [1] and the entropy of classical and quantum systems. On one hand, by restricting Gacs complexity to ergodic classical dynamical systems, we retrieve the equality between the Kolmogorov complexity rate and the Shannon entropy rate derived by A. A. Brudno [2]. On the other hand, using the quantum Shannon-McMillan theorem [3], we show that such an equality holds densely in the case of ergodic quantum spin chains.

FEEDBACK IN OPEN QUANTUM SYSTEMS

1995 ◽  
Vol 09 (11n12) ◽  
pp. 629-654 ◽  
Author(s):  
H. M. WISEMAN
Keyword(s):  
System Dynamics ◽  
Feedback Loop ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Feedback Mechanism ◽  
The Other ◽  
Langevin Equations ◽  
Quantum Trajectories ◽  
Classical Counterpart ◽  
Open Quantum

Open quantum systems continually lose information to their surroundings. In some cases this information can be readily retrieved from the environment and put to good use by engineering a feedback loop to control the system dynamics. Two cases are distinguished: one where the feedback mechanism involves a measurement of the environment, and the other where no measurement is made. It is shown that the latter case can always replicate the former, but not vice versa. This emphasizes the quantum nature of the information being fed back. Two approaches are used to describe the feedback: quantum trajectories (which apply only for feedback based on measurement) and quantum Langevin equations (which can be used in either case), and the results are shown to be equivalent. The obvious applications for the theory are in quantum optics, where the information is lost by radiation damping and can be retrieved by photodetection. A few examples are discussed, one of which is particularly interesting as it has no classical counterpart.

scholarly journals ${\mathcal N}$-FOLD SUPERSYMMETRIC QUANTUM MECHANICS WITH REFLECTIONS

2012 ◽  
Vol 27 (19) ◽  
pp. 1250102 ◽  
Author(s):  
TOSHIAKI TANAKA
Keyword(s):  
Quantum Mechanics ◽  
Hermitian Matrix ◽  
Mechanical Systems ◽  
Quantum Systems ◽  
Supersymmetric Quantum Mechanics ◽  
The Other ◽  
Quantum Mechanical ◽  
Quantum Mechanical Systems ◽  
Ordinary Quantum

We formulate [Formula: see text]-fold supersymmetry in quantum mechanical systems with reflection operators. As in the cases of other systems, they possess the two significant characters of [Formula: see text]-fold supersymmetry, namely, almost isospectrality and weak quasi-solvability. We construct explicitly the most general one- and two-fold supersymmetric quantum mechanical systems with reflections. In the case of [Formula: see text], we find that there are seven inequivalent such systems, three of which are characterized by three arbitrary functions having definite parity while the other four characterized by two arbitrary functions. In addition, four of the seven inequivalent systems do not reduce to ordinary quantum systems without reflections. Furthermore, in certain particular cases, they are essentially equivalent to the most general two-by-two Hermitian matrix two-fold supersymmetric quantum systems obtained previously by us.

Evolution of quantum correlations in the open quantum systems consisting of two coupled oscillators

2017 ◽  
Vol 16 (4) ◽  
Author(s):  
Farkhondeh Abbasnezhad ◽  
Somayeh Mehrabankar ◽  
Davood Afshar ◽  
Mojtaba Jafarpour
Keyword(s):  
Coupled Oscillators ◽  
Open Quantum Systems ◽  
Quantum Correlations ◽  
Quantum Systems ◽  
Open Quantum
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