scholarly journals Quantum thermo-dynamical construction for driven open quantum systems

Quantum ◽  
2021 ◽  
Vol 5 ◽  
pp. 590
Author(s):  
Roie Dann ◽  
Ronnie Kosloff
Keyword(s):  
Quantum Dynamics ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Axiomatic Approach ◽  
Classical Description ◽  
Global Coherence ◽  
Physical Limit ◽  
Transient Control ◽  
Initial Control

Quantum dynamics of driven open systems should be compatible with both quantum mechanic and thermodynamic principles. By formulating the thermodynamic principles in terms of a set of postulates we obtain a thermodynamically consistent master equation. Following an axiomatic approach, we base the analysis on an autonomous description, incorporating the drive as a large transient control quantum system. In the appropriate physical limit, we derive the semi-classical description, where the control is incorporated as a time-dependent term in the system Hamiltonian. The transition to the semi-classical description reflects the conservation of global coherence and highlights the crucial role of coherence in the initial control state. We demonstrate the theory by analyzing a qubit controlled by a single bosonic mode in a coherent state.

scholarly journals Local Spin and Open Quantum Systems: Clarifying Misconceptions, Unifying Approaches

2020 ◽  
Author(s):  
Angel Martín Pendás ◽  
Evelio Francisco
Keyword(s):  
Quantum Control ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Real Space ◽  
Quantum Systems ◽  
Spin Coupling ◽  
Molecular Systems ◽  
Open Quantum ◽  
Local Spin

<p>We now show that Clark and Davidson local spins operators are perfectly defined subsystem operators if a fragment is taken as an <i>open quantum system</i> (OQS). Open systems have become essential in quantum control and quantum computation, but have not received much attention in Chemistry. We have already shown (<i>J. Chem. Theory Comput</i>. <b>2018</b>, <i>15</i>, 1079) how real space OQSs can be defined in molecular systems and how they offer new insights relating quantum mechanical entaglement and chemical bonding. The OQS account of local spin that we offer yields a rigorous, yet easily accessible way to rationalize local spin values. A fragment is found in a mixed state direct sum of sectors characterized by different number of electrons that occur with different probabilities. The local spin is then a weighted sum of otherwise standard <i>S</i>(<i>S</i>+1) values. With OQS glasses, it is obvious that atomic or fragment spins should not vanish. Our approach thus casts doubts on any procedure used to annihilate them, like those used by Mayer and coworkers. OQS local spins allow for a fruitful use of models. One can propose easily sector probabilities for localized, covalent, ionic, zwitterionic, etc. situations, and examine their ideal local spins. We have mapped all 2c-2e cases, and shown how to do that in general multielectron cases. The role of electron correlation is also studied by tuning the Hubbard U/t parameter for H chains. Correlation induced localization changes the spin-coupling patterns even qualitatively, and show how the limiting antiferromagnet arises.</p>

scholarly journals Fermionic duality: General symmetry of open systems with strong dissipation and memory

2021 ◽  
Vol 11 (3) ◽  
Author(s):  
Valentin Bruch ◽  
Konstantin Nestmann ◽  
Jens Schulenborg ◽  
Maarten Wegewijs
Keyword(s):  
Time Evolution ◽  
Quantum Dynamics ◽  
Open Systems ◽  
Broad Class ◽  
Open Quantum Systems ◽  
Causal Structure ◽  
Wide Band ◽  
Quantum Systems ◽  
Strong Interactions ◽  
General Symmetry

We consider the exact time-evolution of a broad class of fermionic open quantum systems with both strong interactions and strong coupling to wide-band reservoirs. We present a nontrivial fermionic duality relation between the evolution of states (Schrödinger) and of observables (Heisenberg). We show how this highly nonintuitive relation can be understood and exploited in analytical calculations within all canonical approaches to quantum dynamics, covering Kraus measurement operators, the Choi-Jamiołkowski state, time-convolution and convolutionless quantum master equations and generalized Lindblad jump operators. We discuss the insights this offers into the divisibility and causal structure of the dynamics and the application to nonperturbative Markov approximations and their initial-slip corrections. Our results underscore that predictions for fermionic models are already fixed by fundamental principles to a much greater extent than previously thought.

scholarly journals Description of Quantum Dynamics of Open Systems Based on Collision-Like Models

2005 ◽  
Vol 12 (01) ◽  
pp. 81-91 ◽  
Author(s):  
Mário Ziman ◽  
Peter Štelmachovič ◽  
Vladimír Bužek
Keyword(s):  
Quantum System ◽  
Quantum Dynamics ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Quantum Systems ◽  
Master Equations ◽  
Discrete Dynamics ◽  
Completely Positive ◽  
Semigroup Property ◽  
System A

Master equations in the Lindblad form describe evolution of open quantum systems that are completely positive and simultaneously have a semigroup property. We analyze the possibility to derive this type of master equations from an intrinsically discrete dynamics that is modelled as a sequence of collisions between a given quantum system (a qubit) with particles that form the environment. In order to illustrate our approach we analyze in detail how the process of an exponential decay and the process of decoherence can be derived from a collision-like model in which particular collisions are described by SWAP and controlled-NOT interactions, respectively.

scholarly journals Time-Reversal Symmetry and Arrow of Time in Quantum Mechanics of Open Systems

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 380 ◽  
Author(s):  
Naomichi Hatano ◽  
Gonzalo Ordonez
Keyword(s):  
Time Reversal ◽  
Quantum Dynamics ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Functional Space ◽  
Time Reversal Symmetry ◽  
Arrow Of Time ◽  
Initial State ◽  
Resonant States ◽  
Complex Eigenvalues

It is one of the most important and long-standing issues of physics to derive the irreversibility out of a time-reversal symmetric equation of motion. The present paper considers the breaking of the time-reversal symmetry in open quantum systems and the emergence of an arrow of time. We claim that the time-reversal symmetric Schrödinger equation can have eigenstates that break the time-reversal symmetry if the system is open in the sense that it has at least a countably infinite number of states. Such eigenstates, namely the resonant and anti-resonant states, have complex eigenvalues. We show that, although these states are often called “unphysical”, they observe the probability conservation in a particular way. We also comment that the seemingly Hermitian Hamiltonian is non-Hermitian in the functional space of the resonant and anti-resonant states, and hence there is no contradiction in the fact that it has complex eigenvalues. We finally show how the existence of the states that break the time-reversal symmetry affects the quantum dynamics. The dynamics that starts from a time-reversal symmetric initial state is dominated by the resonant states for t > 0 ; this explains the phenomenon of the arrow of time, in which the decay excels the growth. The time-reversal symmetry holds in that the dynamic ending at a time-reversal symmetric final state is dominated by the anti-resonant states for t < 0 .

scholarly journals Local Spin and Open Quantum Systems: Clarifying Misconceptions, Unifying Approaches

2020 ◽  
Author(s):  
Angel Martín Pendás ◽  
Evelio Francisco
Keyword(s):  
Quantum Control ◽  
Open Systems ◽  
Open Quantum Systems ◽  
Real Space ◽  
Quantum Systems ◽  
Spin Coupling ◽  
Molecular Systems ◽  
Open Quantum ◽  
Local Spin

<p>We now show that Clark and Davidson local spins operators are perfectly defined subsystem operators if a fragment is taken as an <i>open quantum system</i> (OQS). Open systems have become essential in quantum control and quantum computation, but have not received much attention in Chemistry. We have already shown (<i>J. Chem. Theory Comput</i>. <b>2018</b>, <i>15</i>, 1079) how real space OQSs can be defined in molecular systems and how they offer new insights relating quantum mechanical entaglement and chemical bonding. The OQS account of local spin that we offer yields a rigorous, yet easily accessible way to rationalize local spin values. A fragment is found in a mixed state direct sum of sectors characterized by different number of electrons that occur with different probabilities. The local spin is then a weighted sum of otherwise standard <i>S</i>(<i>S</i>+1) values. With OQS glasses, it is obvious that atomic or fragment spins should not vanish. Our approach thus casts doubts on any procedure used to annihilate them, like those used by Mayer and coworkers. OQS local spins allow for a fruitful use of models. One can propose easily sector probabilities for localized, covalent, ionic, zwitterionic, etc. situations, and examine their ideal local spins. We have mapped all 2c-2e cases, and shown how to do that in general multielectron cases. The role of electron correlation is also studied by tuning the Hubbard U/t parameter for H chains. Correlation induced localization changes the spin-coupling patterns even qualitatively, and show how the limiting antiferromagnet arises.</p>

THE NOTHING THAT REALLY IS!

2016 ◽  
Vol 12 (1) ◽  
pp. 4172-4177
Author(s):  
Abdul Malek
Keyword(s):  
Quantum Dynamics ◽  
Theoretical Physics ◽  
Historical Evolution ◽  
Proper Understanding ◽  
Physical Universe ◽  
Wave Particle Duality ◽  
Negative Effect ◽  
Materialist Interpretation

The denial of the existence of contradiction is at the root of all idealism in epistemology and the cause for alienations.  This alienation has become a hindrance for the understanding of the nature and the historical evolution mathematics itself and its role as an instrument in the enquiry of the physical universe (1). A dialectical materialist approach incorporating  the role of the contradiction of the unity of the opposites, chance and necessity etc., can provide a proper understanding of the historical evolution of mathematics and  may ameliorate  the negative effect of the alienation in modern theoretical physics and cosmology. The dialectical view also offers a more plausible materialist interpretation of the bewildering wave-particle duality in quantum dynamics (2).

The role of branding in establishing open systems

StandardView ◽  
1994 ◽  
Vol 2 (1) ◽  
pp. 18-26
Author(s):  
Roy McKean
Keyword(s):  
Open Systems

scholarly journals Memory Effects in Quantum Dynamics Modelled by Quantum Renewal Processes

Entropy ◽  
2021 ◽  
Vol 23 (7) ◽  
pp. 905
Author(s):  
Nina Megier ◽  
Manuel Ponzi ◽  
Andrea Smirne ◽  
Bassano Vacchini
Keyword(s):  
Quantum Dynamics ◽  
Open Quantum System ◽  
Open Quantum Systems ◽  
Phenomenological Approach ◽  
Quantum Systems ◽  
Renewal Processes ◽  
Continuous Part ◽  
Trace Distance ◽  
Open Quantum ◽  
And Control

Simple, controllable models play an important role in learning how to manipulate and control quantum resources. We focus here on quantum non-Markovianity and model the evolution of open quantum systems by quantum renewal processes. This class of quantum dynamics provides us with a phenomenological approach to characterise dynamics with a variety of non-Markovian behaviours, here described in terms of the trace distance between two reduced states. By adopting a trajectory picture for the open quantum system evolution, we analyse how non-Markovianity is influenced by the constituents defining the quantum renewal process, namely the time-continuous part of the dynamics, the type of jumps and the waiting time distributions. We focus not only on the mere value of the non-Markovianity measure, but also on how different features of the trace distance evolution are altered, including times and number of revivals.

scholarly journals Coherence Effects in Multiple Medium-Induced Radiation

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Fabio Dominguez ◽  
Jose Guilherme Milhano ◽  
Carlos A. Salgado ◽  
Konrad Tywoniuk ◽  
Victor Vila
Keyword(s):  
Time Scales ◽  
Survival Probability ◽  
Jet Quenching ◽  
Close Correspondence ◽  
Gluon Emission ◽  
Classical Description ◽  
Theoretical Support ◽  
Coherence Effects ◽  
Hard Gluon

In the first part of this work we study the color coherence phenomenon by considering the well-known quark-antiquark antenna with an in-medium hard gluon emission and an extra very soft emission outside it—double antenna. By discussing the coherence effects in terms of the survival probability, we generalize previous studies of the antenna radiation to the case of more than two emitters. After providing support to the jet quenching picture with effective emitters in the QCD cascade, we present a novel setup of an antenna splitting inside the medium taking into account the finite formation time of the dipole, which turns out to be an important scale. We read into the role of coherence and the relevant time scales which control the scenario, while also providing theoretical support for vacuum-like emissions early in the medium. Finally, by mapping the spectrum of in-medium splittings through the corresponding kinematical Lund diagram, we appreciate regimes of a close correspondence to a semi-classical description.

Correlation between myocardial contractile force and cytosolic inorganic phosphate during early ischemia

1997 ◽  
Vol 272 (3) ◽  
pp. H1333-H1341 ◽  
Author(s):  
M. X. He ◽  
S. Wang ◽  
H. F. Downey
Keyword(s):  
Inorganic Phosphate ◽  
Contractile Force ◽  
Left Ventricular ◽  
Resonance Spectroscopy ◽  
Rat Hearts ◽  
Initial Control ◽  
Myocardial Contractile Force ◽  
Myocardial Contractile ◽  
Developed Pressure

To test the role of inorganic phosphate (Pi) in downregulation of myocardial contractile force at the onset of ischemia, Pi of rat hearts was determined with 31P nuclear magnetic resonance spectroscopy. Forty cycles of brief hypoperfusion (30% of baseline flow for 33 s) were used to achieve a time resolution of 0.512 s for comparing dynamic changes in Pi and contractile force. Initial control values of left ventricular developed pressure (LVP), heart rate, and oxygen consumption were 136 +/- 11 mmHg, 236 +/- 4 beats/min, and 95 +/- 3 microl O2 x min(-1) x g(-1); these values were unchanged at the end of the experiment. During the first 10 s of hypoperfusion, Pi increased at a rate (percentage of the total observed change) faster than the decrease in LVP; Pi and LVP then changed at the same rate during the remainder of the hypoperfusion. ADP did not change in advance of LVP. Intracellular pH did not change. The results indicate that Pi plays an important role in initiating the downregulation of myocardial contractile force at the onset of ischemia. Perfusion pressure also declined faster than LVP at the onset of ischemia, indicating potential importance of vascular collapse in contractile downregulation during early ischemia.

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