scholarly journals Thermodynamic Cost of Quantum transfers

2021 ◽  
Author(s):  
Forouzan Mirmasoudi ◽  
Sodeif Ahadpour
Keyword(s):  
Excited States ◽  
Energy Cost ◽  
Quantum Fisher Information ◽  
Quantum Correlations ◽  
Spin Squeezing ◽  
Quantum Systems ◽  
Control Parameters ◽  
Dense Coding ◽  
Optimal Dense Coding ◽  
Coding Capacity

Abstract In this work, we will study thermodynamic cost of dense coding. In this regard, a scheme is proposed for quantum channel where is induced from two initially uncorrelated thermal quantum systems. At first, the quantum Fisher information and spin squeezing is used to quantify the correlation dynamics over the system. The system reveals that the dynamics of quantum correlations depends crucially on specific energy and temperature. Also, they can be utilized as control parameters for optimal dense coding. Several interesting features of the variations of the energy cost and the dense coding capacity are obtained. It can keep its own valid capacity value in a broad range of temperature by increasing in the energy value of excited states. Also, we can identify valid dense coding with the help of calculating energy cost in the system. Using this approach, identifying a critical point of this model in dense coding capacity quality can be very effective.

scholarly journals Super dense coding in one-axis twisting model

2020 ◽  
Vol 66 (3 May-Jun) ◽  
pp. 356
Author(s):  
S. Ahadpour ◽  
F. Mirmasoudi
Keyword(s):  
Thermal Properties ◽  
Quantum Correlations ◽  
Spin Squeezing ◽  
Spin Model ◽  
Dense Coding ◽  
The Relationship ◽  
Coding Capacity ◽  
Depen Dencies

We study thermal dense coding in a two-spin model under an external magnetic eld. Its depen-dencies on magnetic eld, strength of the spin squeezing and temperature are presented in detail.Our main goal now is to study how we can increase the thermal dense coding capacity in the presenceof magnetic eld, strength of the spin squeezing and temperature. It shows that the dense codingtend to valid value by setting the value of the input quantum correlations. Our most importantmotive for this study is to examine the relationship between the thermal properties of super quan-tum discord (SQD) and dense coding. The results show that the thermal properties of the SQD onour channel enable us to determine when and under what conditions the system is suitable for validdense coding. Our proposals could be lead to that this scheme is efficient for quantum informationprocessing.

Thermal Entanglement and Dense Coding in Two-Qubit XX Spin Chain under an Arbitrary Magnetic Field

2013 ◽  
Vol 446-447 ◽  
pp. 986-991
Author(s):  
Hai Lin Huang ◽  
Zhao Yu Sun
Keyword(s):  
Magnetic Field ◽  
Thermal State ◽  
Arbitrary Orientation ◽  
Dense Coding ◽  
Thermal Entanglement ◽  
Optimal Direction ◽  
Optimal Dense Coding ◽  
Arbitrary Magnetic Field ◽  
Coding Capacity ◽  
The Magnetic Field

The effect of arbitrary orientation in the magnetic field on the entanglement and dense coding of a two-qubit XX model is investigated. The concurrence and optimal dense coding capacity are calculated for different orientations of the magnetic field. It is found that the entanglement can be maximized by rotating the magnetic field to an optimal direction at given temperature. Furthermore, there exists critical concurrence Cc, beyond which the thermal state is unfeasible for optimal dense coding.

scholarly journals Topological pumping of a 1D dipolar gas into strongly correlated prethermal states

Science ◽  
2021 ◽  
Vol 371 (6526) ◽  
pp. 296-300
Author(s):  
Wil Kao ◽  
Kuan-Yu Li ◽  
Kuan-Yu Lin ◽  
Sarang Gopalakrishnan ◽  
Benjamin L. Lev
Keyword(s):  
Excited States ◽  
Interaction Strength ◽  
Quantum Correlations ◽  
Quantum Systems ◽  
Strongly Correlated ◽  
Quantum Gas ◽  
Dipolar Interactions ◽  
Fundamental Interest ◽  
One Dimensional ◽  
Particle Measurements

Long-lived excited states of interacting quantum systems that retain quantum correlations and evade thermalization are of great fundamental interest. We create nonthermal states in a bosonic one-dimensional (1D) quantum gas of dysprosium by stabilizing a super-Tonks-Girardeau gas against collapse and thermalization with repulsive long-range dipolar interactions. Stiffness and energy-per-particle measurements show that the system is dynamically stable regardless of contact interaction strength. This enables us to cycle contact interactions from weakly to strongly repulsive, then strongly attractive, and finally weakly attractive. We show that this cycle is an energy-space topological pump (caused by a quantum holonomy). Iterating this cycle offers an unexplored topological pumping method to create a hierarchy of increasingly excited prethermal states.

scholarly journals Thermal quantum correlations of spin chain with multiple interactions

2020 ◽  
Vol 66 (5 Sept-Oct) ◽  
pp. 692
Author(s):  
S. Ahadpour ◽  
F. Mirmasoudi
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Quantum Correlations ◽  
Dense Coding ◽  
Correlated Channels ◽  
The Impact ◽  
Coding Capacity ◽  
Multiple Interactions ◽  
Moriya Interaction

In order to explore the impact of distance between spins on quantum correlation, we compute trace ditance discord (TDD) and spin squeezing in an anisotropic Heisenberg XYZ model with Dzyaloshinskii-Moriya interaction in the presence of the external magnetic field. It is valuable to investigate that how we can protect quantum correlations in system when the distance between the spins is promoted. We find that rich Dzyaloshinskii-Moriya interaction and low temperature can be effective for quantum correlations with increasing distance between spins. As, at sufficeintly low temperature In addition, the generated correlated channels are inspected to interchange the information between the system qubits applying the standard dense coding protocol; then, the dense coding capacity of the transmitted information is quantified. It is found that the strength Dzyaloshinskii-Moriya interaction and magnetic field have a great impact on the dynamics of the quantum correlations and, consequently, the quality of the generated channels to exchange the information.  Therefore, the effect of Dzyaloshinskii-Moriya interaction for various strengths of temperature needs to be considered to have valid dense coding when distance of spin increases.

scholarly journals Cyclic quantum causal models

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonathan Barrett ◽  
Robin Lorenz ◽  
Ognyan Oreshkov
Keyword(s):  
Causal Reasoning ◽  
Causal Structure ◽  
Bell Inequalities ◽  
Quantum Correlations ◽  
Quantum Systems ◽  
Causal Models ◽  
Causal Order ◽  
Quantum Processes ◽  
Causal Explanations ◽  
Causal Structures

AbstractCausal reasoning is essential to science, yet quantum theory challenges it. Quantum correlations violating Bell inequalities defy satisfactory causal explanations within the framework of classical causal models. What is more, a theory encompassing quantum systems and gravity is expected to allow causally nonseparable processes featuring operations in indefinite causal order, defying that events be causally ordered at all. The first challenge has been addressed through the recent development of intrinsically quantum causal models, allowing causal explanations of quantum processes – provided they admit a definite causal order, i.e. have an acyclic causal structure. This work addresses causally nonseparable processes and offers a causal perspective on them through extending quantum causal models to cyclic causal structures. Among other applications of the approach, it is shown that all unitarily extendible bipartite processes are causally separable and that for unitary processes, causal nonseparability and cyclicity of their causal structure are equivalent.

FRUSTRATED TRANSVERSE ISING MODELS: A CLASS OF FRUSTRATED QUANTUM SYSTEMS

1992 ◽  
Vol 06 (14) ◽  
pp. 2439-2469 ◽  
Author(s):  
P. SEN ◽  
B. K. CHAKRABARTI
Keyword(s):  
Excited States ◽  
Transverse Field ◽  
Ising Models ◽  
Quantum Systems ◽  
Nearest Neighbour ◽  
Competing Interactions ◽  
Annni Model ◽  
Kirkpatrick Model ◽  
Transverse Fields ◽  
Exact Diagonalisation

The analytical and numerical (Monte Carlo and exact diagonalisation) estimates of phase diagrams of frustrated Ising models in transverse fields are discussed here. Specifically we discuss the Sherrington–Kirkpatrick model in transverse field and the Axial Next-Nearest Neighbour Ising (ANNNI) model in transverse field. The effects of quantum fluctuations (induced by the transverse field) on the ground and excited states of such systems with competing interactions (frustration) are also discussed. The results are compared to those available for other frustrated quantum systems.

scholarly journals USE OF THE WHIRLIGIG PRINCIPLE FOR STABILIZING THE INITIAL STATES OF SOME CLASSIC AND QUANTUM SYSTEMS

2020 ◽  
pp. 78-81
Author(s):  
V.A. Buts
Keyword(s):  
Quantum System ◽  
Excited States ◽  
Quantum Systems ◽  
Nuclear Systems ◽  
Initial States

It is shown that the whirligig principle can be used for stabilization of the initial states of some classical and quantum systems. This feature of the whirligig principle is demonstrated by simple examples. The most important result of this work is the proof of the fact that the stabilization of the excited states of quantum systems can be realized by acting not on the quantum system itself, but by acting on the states into which the system must go. Potentially, this result can be used to stabilize excited nuclear systems.

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