scholarly journals Extractable quantum work from a two-mode Gaussian state in a noisy channel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Marina Cuzminschi ◽  
Alexei Zubarev ◽  
Aurelian Isar
Keyword(s):  
Open System ◽  
Thermal State ◽  
Heterodyne Detection ◽  
Gaussian State ◽  
Noisy Channel ◽  
Work Efficiency ◽  
Initial State ◽  
System Parameters ◽  
Information Work ◽  
Lindblad Master Equation

AbstractWe study a Szilard engine based on a Gaussian state of a system consisting of two bosonic modes placed in a noisy channel. As the initial state of the system is taken an entangled squeezed thermal state, and the quantum work is extracted by performing a measurement on one of the two modes. We use the Markovian Kossakowski-Lindblad master equation for describing the time evolution of the open system and the quantum work definition based on the second order Rényi entropy to simulate the engine. We also study the information-work efficiency of the Szilard engine as a function of the system parameters. The efficiency is defined as the ratio of the extractable work averaged over the measurement angle and the erasure work, which is proportional to the information stored in the system. We show that the extractable quantum work increases with the temperature of the reservoir and the squeezing between the modes, average numbers of thermal photons and frequencies of the modes. The work increases also with the strength of the measurement, attaining the maximal values in the case of a heterodyne detection. The extractable work is decreasing by increasing the squeezing parameter of the noisy channel and it oscillates with the phase of the squeezed thermal reservoir. The efficiency mostly has a similar behavior with the extractable quantum work evolution. However information-work efficiency decreases with temperature, while the quantity of the extractable work increases.

scholarly journals Extractable quantum work from a two-mode Gaussian state in a noisy channel

2021 ◽  
Author(s):  
Marina Cuzminschi ◽  
Isar Aurelian ◽  
Alexei Zubarev
Keyword(s):  
Master Equation ◽  
Time Evolution ◽  
Open System ◽  
Thermal State ◽  
Second Order ◽  
Heterodyne Detection ◽  
Gaussian State ◽  
Noisy Channel ◽  
Initial State ◽  
Lindblad Master Equation

Abstract We study a Szilard engine based on a Gaussian state of a system consisting of two bosonic modes placed in a noisy channel. As the initial state of the system is taken an entangled squeezed thermal state, and the quantum work is extracted by performing a measurement on one of the two modes. We use the Markovian Kossakowski-Lindblad master equation for describing the time evolution of the open system and the quantum work definition based on the second order R\'{e}nyi entropy to simulate the engine. We show that the extractable quantum work increases with the temperature of the reservoir and the squeezing between the modes, average numbers of thermal photons and frequencies of the modes. The work increases also with the strength of the measurement, attaining the maximal values in the case of a heterodyne detection. As well the extractable work is decreasing by increasing the squeezing parameter of the noisy channel and it oscillates with the phase of the squeezed thermal reservoir.

scholarly journals Quantum correlations for two coupled oscillators interacting with two heat baths

2020 ◽  
Vol 98 (4) ◽  
pp. 327-331
Author(s):  
I.V. Dudinetc ◽  
V.I. Man’ko
Keyword(s):  
Equilibrium State ◽  
Coupled Oscillators ◽  
Thermal State ◽  
Heat Bath ◽  
Quantum Correlations ◽  
Harmonic Oscillators ◽  
Time Dependent ◽  
Gaussian State ◽  
Initial State ◽  
Dependent State

We study a system of two coupled oscillators (A oscillators), each of which linearly interact with their own heat bath consisting of a set of independent harmonic oscillators (B oscillators). The initial state of the A oscillator is taken to be coherent while the B oscillator is in a thermal state. We analyze the time-dependent state of the A oscillator, which is a two-mode Gaussian state. By making use of Simon’s separability criterion, we show that this state is separable for all times. We consider the equilibrium state of the A oscillator in detail and calculate its Wigner function.

scholarly journals Entanglement of thermal state of quantum annealing processor

2020 ◽  
Vol 24 (Suppl. 1) ◽  
pp. 325-332
Author(s):  
Abdel-Haleem Abdel-Aty ◽  
Ahmad Khedr ◽  
Amr Youssef ◽  
Yasser Saddeek
Keyword(s):  
Quantum Correlation ◽  
Thermal State ◽  
Quantum Correlations ◽  
Chain Model ◽  
Spin Orbit Coupling ◽  
Coupling Constant ◽  
Quantum Annealing ◽  
System Parameters ◽  
Spin Chain Model ◽  
System Nodes

We investigate the dynamics of quantum correlations between the quantum annealing processor nodes. The quantum annealing processor is simulated by spin-chain model. It is assumed that system started from the thermal state. The Hamiltonian of the system is mathematically designed and analytically solved. The properties of the system are investigated. Negativity is used to investigate the dynamics of quantum correlation between the system nodes. The effect of the system parameters (spin-orbit coupling, coupling constant, and bias parameter) on the dynamics of negativity is explored. Results showed that the coupling constant had a great effect in the dynamics of the quantum correlation.

Amplified thermal state: Properties and decoherence

2021 ◽  
pp. 2150448
Author(s):  
Zheng-Yin Zhao ◽  
Xue-Xiang Xu
Keyword(s):  
Light Intensity ◽  
Amplification Factor ◽  
Thermal State ◽  
Signal To Noise Ratio ◽  
Photon Number ◽  
Gaussian State ◽  
Matrix Elements ◽  
Number Operator ◽  
Signal To Noise ◽  
Photon Loss

In this paper, we introduce the amplified thermal state (ATS) by operating [Formula: see text] on the thermal state (TS). Here, [Formula: see text] is the amplification factor and [Formula: see text] is the photon number operator. We study its properties, such as light intensity, signal-to-noise ratio (SNR), Fock matrix elements and Wigner function. In addition, we study its decoherence in photon-loss channel by analyzing evolution of all above properties. All considered properties are derived analytically and simulated numerically. Compared with the original TS, the amplification can enhance light intensity and SNR, remain the mixed character, and exhibit non-Gaussianity. While the decoherence will weaken light intensity and SNR, remain the mixed character, and return to Gaussian state.

Quantum feedback control for qubit-qutrit entanglement

2016 ◽  
Vol 16 (7&8) ◽  
pp. 597-614
Author(s):  
Tiantian Ma ◽  
Jun Jing ◽  
Yi Guo ◽  
Ting Yu
Keyword(s):  
Feedback Control ◽  
Open System ◽  
Control Mechanism ◽  
Initial State ◽  
Level Atom ◽  
Control Scheme ◽  
Quantum Feedback ◽  
Local Feedback ◽  
Quantum Open System ◽  
Different Parts

We study a hybrid quantum open system consisting of two interacting subsystems formed by one two-level atom (qubit) and one three-level atom (qutrit). The quantum open system is coupled to an external environment (cavity) via the qubit-cavity interaction. It is found that the feedback control on different parts of the system (qubit or qutrit) gives dramatically different asymptotical behaviors of the open system dynamics. We show that the local feedback control mechanism acting on the qutrit subsystem is superior than that on the qubit in the sense of improving the entanglement. Particularly, the qutrit-control scheme may result in an entangled steady state, depending on the initial state.

Physiotherapy for hypertensive disease from the perspectives of chaotic dynamics of cardiovascular system parameters in patients

10.12737/7242 ◽  
2014 ◽  
Vol 8 (1) ◽  
pp. 0-0 ◽  
Author(s):  
Горбунов ◽  
D. Gorbunov ◽  
Эльман ◽  
Kseniya Elman ◽  
Гараева ◽  
...  
Keyword(s):  
Phase Space ◽  
Cardiovascular System ◽  
Chaotic Dynamics ◽  
Hypertensive Disease ◽  
Initial State ◽  
Hypertensive Patients ◽  
System Parameters ◽  
Calculation Of Parameters ◽  
Effi Ciency ◽  
Two Stages

The problem of one-type uncertainty is solved when cardiovascular system parameters in hypertensive patients undergoing physiotherapy aren’t differentiated by stochastics, but these differences are clearly revealed by the methods of neurocomputing and calculation of parameters of quasi-attractors. Simultaneously, the solution of system synthesis problem is possible, i.e. identification of more important diagnostic characters xi from the whole set of state vector of cardiovascular system x(t) in hypertensive patients. Efficiency of physiotherapy is estimated at two stages of course of treatment: in the initial state (initial physiotherapy) and after the termination of course of treatment. The dynamics of motion of quasi-attractors in phase space of states in hypertensive patients is shown. Thus, the problem of elimination of one-type uncertainty in studying the effi-ciency of curative measures is solved.

Optimizing the lever propelling system for manual wheelchairs

2012 ◽  
Vol 60 (4) ◽  
pp. 793-800 ◽  
Author(s):  
W. Choromański ◽  
K. Fiok ◽  
G. Dobrzyński
Keyword(s):  
Experimental Data ◽  
Optimization Method ◽  
Drive System ◽  
Knowledge Gap ◽  
Work Efficiency ◽  
System Parameters ◽  
Axis Of Rotation ◽  
Manual Wheelchairs ◽  
Individual Human

Abstract The article concerns the optimization of manual wheelchairs with a lever propelling system. Lever-driven manual wheelchairs are a promising wheelchair group, however they still need to be improved in order to compete successfully with classic manual push rim-driven wheelchairs. Also, despite all manual wheelchairs human work efficiency during propulsion plays an important role, there is not enough research carried out that would focus on this problem regarding lever-driven wheelchairs. The research, presented in this paper, according to the authors’ intention, is to make this knowledge gap smaller. The article describes an analytical optimization method for adjusting important lever-drive system parameters - levers length and its axis of rotation position - to individual human anthropometry. The method is based on experimental data regarding maximum human push capabilities acquired in another study. The optimized parameters’ values were determined after assessment of maximum human expendable energy during a single work phase (pushing the levers). As a result of this study authors determined optimal levers length and their axis of rotation position for a 50 percentile French male. The carried out research shows also, that the suboptimal area for positioning the levers axis of rotation is relatively wide.

scholarly journals On non-Markovian Time Evolution in Open Quantum Systems

2007 ◽  
Vol 14 (03) ◽  
pp. 265-274 ◽  
Author(s):  
Andrzej Kossakowski ◽  
Rolando Rebolledo
Keyword(s):  
Time Evolution ◽  
Open System ◽  
Open Quantum Systems ◽  
Vacuum State ◽  
Quantum Systems ◽  
Initial State ◽  
Completely Positive ◽  
Open Quantum

Non-Markovian reduced dynamics of an open system is investigated. In the case when the initial state of the reservoir is the vacuum state, an approximation is introduced which makes it possible to construct a reduced dynamics which is completely positive.

Reducing quantum-memory-assisted entropic uncertainty by weak measurement and weak measurement reversal

2015 ◽  
Vol 13 (05) ◽  
pp. 1550037 ◽  
Author(s):  
Yanliang Zhang ◽  
Maofa Fang ◽  
Guodong Kang ◽  
Qingping Zhou
Keyword(s):  
Quantum Information Processing ◽  
Weak Measurement ◽  
Quantum Memory ◽  
Noisy Channel ◽  
Dynamic Features ◽  
Initial State ◽  
Positive Role ◽  
Entropic Uncertainty Relation ◽  
Qubit System ◽  
Before And After

We have investigated the dynamic features of the quantum-memory-assisted entropic uncertainty relation (QMA EUR) in the amplitude damping (AD) channel. The initial state of qubit system and quantum memory system shared between Alice and Bob is assumed as extended by Werner-like (EWL) state. To reduce the amount of entropic uncertainty of Pauli observables in this noisy channel, we presented a reduction scheme by means of weak measurements (WMs) and weak measurement reversals (WMRs) before and after the entangled system subjecting to the noisy channel. It is shown that the prior WM and poster WMR can effectively reduce quantity of entropic uncertainty, but the poster WM operation cannot played a positive role on reduction of quantity of entropic uncertainty. We hope that our proposal could be verified experimentally and might possibly have future applications in quantum information processing.

scholarly journals Asymptotic Entanglement Sudden Death in Two Atoms with Dipole–Dipole and Ising Interactions Coupled to a Radiation Field at Non-Zero Detuning

Entropy ◽  
2021 ◽  
Vol 23 (5) ◽  
pp. 629
Author(s):  
Gehad Sadiek ◽  
Wiam Al-Dress ◽  
Salwa Shaglel ◽  
Hala Elhag
Keyword(s):  
Asymptotic Behavior ◽  
Sudden Death ◽  
Radiation Field ◽  
Quantum Correlation ◽  
Bell State ◽  
Single Mode ◽  
Mean Value ◽  
Entanglement Sudden Death ◽  
Initial State ◽  
System Parameters

We investigate the time evolution and asymptotic behavior of a system of two two-level atoms (qubits) interacting off-resonance with a single mode radiation field. The two atoms are coupled to each other through dipole--dipole as well as Ising interactions. An exact analytic solution for the system dynamics that spans the entire phase space is provided. We focus on initial states that cause the system to evolve to entanglement sudden death (ESD) between the two atoms. We find that combining the Ising and dipole--dipole interactions is very powerful in controlling the entanglement dynamics and ESD compared with either one of them separately. Their effects on eliminating ESD may add up constructively or destructively depending on the type of Ising interaction (Ferromagnetic or anti-Ferromagnetic), the detuning parameter value, and the initial state of the system. The asymptotic behavior of the ESD is found to depend substantially on the initial state of the system, where ESD can be entirely eliminated by tuning the system parameters except in the case of an initial correlated Bell state. Interestingly, the entanglement, atomic population and quantum correlation between the two atoms and the field synchronize and reach asymptotically quasi-steady dynamic states. Each one of them ends up as a continuous irregular oscillation, where the collapse periods vanish, with a limited amplitude and an approximately constant mean value that depend on the initial state and the system parameters choice. This indicates an asymptotic continuous exchange of energy (and strong quantum correlation) between the atoms and the field takes place, accompanied by diminished ESD for these chosen setups of the system. This system can be realized in spin states of quantum dots or Rydberg atoms in optical cavities, and superconducting or hybrid qubits in linear resonators.

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