Sudden Birth Research Articles

New features of the stationary and moving atom–atom entanglement

In this paper, we introduce useful scheme of the atom–atom interaction in the case of absence and presence of the atomic motion effect. The quantum entanglement between the two two-level atoms based on concurrence quantifier will be investigated. The dependence atom–atom entanglement on the different system parameters will be examined. Moreover, the influence of the atomic motion and initial state setting on the dynamical behavior of the entanglement between two atoms will be discussed. Furthermore, we have explored some important phenomena related to the entanglement between two atoms such as entanglement sudden death (ESD) and entanglement sudden birth (ESB). Finally, we have obtained a high amount of the atom–atom entanglement by a proper choice of the system parameters in the case of stationary and moving atoms.

Thermal effect on the generated quantum correlation between two superconducting qubits

Quantum correlations in two superconducting (SC) qubits, placed in an SC-cavity and driven by noise fields, are investigated by using quantum discord (QD) and measurement-induced nonlocality with quantum entanglement (QE). It was found that the initial values of QD and measurement-induced non-locality (MIN) grow from zero-values to non-zero values. This growth of quantum correlations is due to the unitary qubits–field interaction. It is found that by increasing the coupling to the thermal environment, the generated correlations (of QD, MIN and QE) return to their zero-values and the phenomena of the sudden death and sudden birth only occur for QE. It is interesting to note that the state of two superconducting qubits has the quantum discord and quantum nonlocality without entanglement. The ability of the thermal field parameter for the disappearance of the generated correlations depend on the spontaneous emission parameter and vice versa.

Quantum Fisher information of the GHZ state due to classical phase noise lasers under non-Markovian environment

The dynamics of N-qubit GHZ state quantum Fisher information (QFI) under phase noise lasers (PNLs) driving is investigated in terms of non-Markovian master equation. We first investigate the non-Markovian dynamics of the QFI of N-qubit GHZ state and show that when the ratio of the PNL rate and the system–environment coupling strength is very small, the oscillations of the QFIs decay slower which corresponds to the non-Markovian region; yet when it becomes large, the QFIs monotonously decay which corresponds to the Markovian region. When the atom number N increases, QFIs in both regions decay faster. We further find that the QFI flow disappears suddenly followed by a sudden birth depending on the ratio of the PNL rate and the system–environment coupling strength and the atom number N, which unveil a fundamental connection between the non-Markovian behaviors and the parameters of system–environment couplings. We discuss two optimal positive operator-valued measures (POVMs) for two different strategies of our model and find the condition of the optimal measurement. At last, we consider the QFI of two atoms with qubit–qubit interaction under random telegraph noises (RTNs).

Generalized discord, entanglement, Einstein–Podolsky–Rosen steering, and Bell nonlocality in two-qubit systems under (non-)Markovian channels: Hierarchy of quantum resources and chronology of deaths and births

Generalized quantum discord $(D_q)$, Einstein-Podolsky-Rosen steering $(S)$, entanglement $(E)$, and Bell nonlocality ($N$), are logically distinct quantifiers of quantum correlations. All these measures capture nonclassical aspects of quantum states and play some role as resources in quantum information processing. In this work, we look for the hierarchy satisfied by these quantum correlation witnesses for a class of two-qubit states. We show that $N \triangleright S\triangleright E\triangleright D_q$, meaning that nonlocality implies steering, which in turn implies entanglement, which then implies $q$-discord. For the quantum states under concern, we show that the invariance of this hierarchy under noisy quantum channels directly implies a death chronology. Additionally, we have found that sudden death of all quantum resources except discord is absent only for a subset of states of measure zero. At last, we provide an illustration of another consequence of the aforementioned hierarchy, namely, the existence of a sudden birth chronology under non-Markovian channels.

Gaussian quantum steering and its asymmetry in curved spacetime

We study Gaussian quantum steering and its asymmetry in the background of a Schwarzschild black hole. We present a Gaussian channel description of quantum state evolution under the influence of the Hawking radiation. We find that thermal noise introduced by Hawking effect will destroy the steerability between an inertial observer Alice and an accelerated observer Bob who hovers outside the event horizon, while it generates steerability between Bob and a hypothetical observer anti-Bob inside the event horizon. Unlike entanglement behaviors in curved spacetime, here the steering from Alice to Bob suffers from a "sudden death" and the steering from anti-Bob to Bob experiences a "sudden birth" with increasing Hawking temperature. We also find that the Gaussian steering is always asymmetric and the maximum steering asymmetry cannot exceed $\ln 2$, which means the state never evolves to an extremal asymmetry state. Furthermore, we obtain the parameter settings that maximize steering asymmetry and find that (i) $s=arccosh(\frac{\cosh^2 r}{1-\sinh^2r})$ is the critical point of steering asymmetry, and (ii) the attainment of maximal steering asymmetry indicates the transition between one-way steerability and both-way steerability for the two-mode Gaussian state under the influence of Hawking radiation.

Utopia and Progress: The Case of Thomas Paine's Apocalypse

One of the overlooked aspects of political utopianism is the mechanism which brings about the utopia. What brings about the change from the ordinary politics of the present to the utopian state? For Thomas Paine the change is apocalyptic. Paine’s later writing testifies to the sudden birth of reason in the world and foresees its sweeping effect over individual human minds and human societies. He describes reason as an irresistible revelation, an apocalypse. Evaluating the American and French revolutions, Paine identifies the mechanism of change as the rational apocalypse itself. On the one hand, this mechanism of change shatters the coherence of Paine’s comprehensive thought. On the other, Paine’s utopianism is both thought-provoking and cautionary. To what extent can reason enlighten individuals to their true interests in harmony with others? To what extent do utopian plans for society rely on something miraculous or apocalyptic to change human consciousness? Should political utopianism purport to fix the problems of the world now, or is it primarily a device for imagining a better world which future generations might slowly construct?

Distillability sudden death and sudden birth in a two-qutrit system under decoherence at finite temperature

Distillability sudden death and sudden birth in a two-qutrit system locally subject to amplitude damping channel at a finite temperature have been studied in detail. By using the negativity and the realignment criterion, the results show that certain initially prepared free entangled states under amplitude damping channel at a finite temperature may become bound entangled or separable states in a finite time. Moreover, we have also demonstrated initially prepared bound entangled or separable states may also become distillable entangled states in a finite time.

A life uncertain - My baby's vulnerability: Mothers' lived experience of connection with their preterm infants in a Botswana neonatal intensive care unit.

BackgroundPreterm and low–birth weight infants are often separated from their mothers when admitted to neonatal units for stabilisation of body temperature and technological support.ObjectivesThe aim of the study was to explore and describe the lived experiences of mothers regarding care of their hospitalised preterm infants in a neonatal unit in a public hospital in Gaborone, Botswana.MethodThis study utilised a qualitative exploratory and descriptive phenomenological study design. Mothers of hospitalised preterm infants were purposefully selected, with whom there was extensive engagement. Two in-depth interviews were conducted with each participant (P).ResultsMothers were shocked by the sudden birth of a preterm infant and found the neonatal environment intimidating. This increased their fear and anxiety and delayed development of a relationship with their infants. Support from staff, other mothers in the neonatal unit and family members enabled the mothers to overcome their fear and to develop an emotional connection with their infants.ConclusionOn-going supportive communication with the mothers by healthcare professionals promotes their confidence and competence in caring for their preterm infants, which in turn promotes mother–infant attachment.

Thermal Entanglement Properties in two Kinds of Two-qubit Spin Squeezing Model

Using the concurrence (C) criterion, we investigate the thermal entanglement properties in two-qubit spin squeezing model for two kinds of squeezing interaction: one-axis twisting model (OATM) and two-axis countertwisting model (TACM) with a transverse field. To the OATM, in the limit case of T→0, the ground state entanglement is initially increased from zero to the maximum value, then decreased in a period of time and suddenly disappeared finally with further enhancing the external magnetic field Ω. One interesting thing is that instead of decaying slowly to zero the entanglement is sudden disappeared with further enhancing Ω or μ (the spin squeezing interaction in X direction), and decreasing the parameter μ or Ω can obviously broaden the scope of entanglement exists. For the finite temperature case, a novelty point is the sudden birth phenomenon occured in the behaviors of entanglement, it is initially to be zero (persists for some time), with further improving Ω and μ the entanglement will be suddenly appeared, and the time interval (persists to be zero) before sudden birth is obviously prolonged with decreasing two parameters. The temperature range of entanglement exists can be extended evidently with increasing μ or Ω, and one can obtain entanglement at higher temperature through changing them. When to the TACM, the ground state entanglement is initially decreased from the maximum value and then suddenly disappeared with increasing Ω. While increasing γ the ground state entanglement is increased initially from zero to the maximum value and then sudden disappeared with further improving γ (the spin squeezing interaction in XY plane), proper tuing γ or Ω can prolong the lives of entanglement evidently. For the finite temperature case, the sudden birth phenomenon also occured in the the evoluted concurrence, the variation of parameters Ω and γ can reduce the time interval before sudden birth. The influence of the temperature T on thermal entanglement property is also investigated. The temperature range of entanglement existence can be extended evidently with increasing γ, one can obtain entanglement at higher temperature through changing parameters γ and Ω.

Dynamics of the Bipartite and Multipartite Entanglement in the Heisenberg Chain with Dzyaloshinskii-Moriya Interaction

We study and compare the dynamics of the bipartite entanglement (BE) and multipartite entanglement (ME) in the Heisenberg chain with Dzyaloshinskii-Moriya (DM) interaction. We have shown that the DM interaction can induce both entanglement sudden death and entanglement sudden birth in the BE, while no such phenomena occurs in the ME features of the systems. The robustness dynamic of ME in the time domain would be interesting to those are working in the quantum information and quantum computing communities.

Sudden Death, Sudden Birth, and Nonclassical Effects of Photon-Added Power-Law Potential Within the Framework of Subsystem-Environment Correlations

Recently photon-added states that could be detected through the emission rather than the absorption of electromagnetic radiation have been actively explored and investigated. In this paper, we construct the photon-added power-law-potential coherent states (PA-PLPCSs) using generalized Heisenberg algebra. The Klauder minimal set of conditions required to obtain coherent states are satisfied. We study nonclassical effects associated with PA-PLCSs using the Mandel parameter and discuss some of their intriguing nonclassical behavior. These states have interesting significance and can be realized experimentally, exhibiting highly nonclassical behavior that depends on the degree of excitation and other parameters. Finally, we study the dynamics of entanglement and quantum discord for two-mode state within the framework of PLPCSs and show that the sudden death and sudden birth of correlations are due to the change and transfer of the correlation between one mode and its environment, using the monogamic relation between the entanglement and quantum discord.

Solving the qubit coupled with reservoir under time-varying external field with Ket-Bra Entangled State Method

In this paper, we first make a brief review of the general method of solving master equation of density operator, which includes the C-number method method and the super-operator method. The C-number can transform quantum master equation into Fokker-Plank equation or the differential equation of density matrix elements, and this method has a wide applicable range but the Fokker-Plank equation and differential equation are difficult to solve. Besides, the solution is not always applicable for any initial condition. The super-operator method can solve master equation efficiently compared with C-number method, however the solving process of super-operator method mostly depends on the characteristics of Lie algebra. For instance, if the corresponding Lindblad operator can be divided into the generators of Su(2) or Su(1,1) Lie group, the super-operator is no longer applicable. Thus although super-operator is more efficiently than C-number method, it has a narrow applicable range. Furthermore, other researchers have made much effort to develop super-operator method, for instance, S.J. Wang proposed the left and right action operator, the left operator is the same as the general operator, while the right action operator from the right side acts on other general operator, thus the explicit formation of super-operator can be given by this method. Fan proposed the thermal entangled state representation which can convert operator between real mode and fictitious mode. All these developments depend on Lie algebra, thus they all have a narrow applicable range just like super-operator method. We introduce a new Ket-Bra entangled state (KBES) method in this paper, which can transform master equation into Schrodinger-like equation with the corresponding Ket-Bra entangled state. Then one can use the method of Schrodinger equation such as time evolution method, perturbation method, etc. to solve the master equation. Compared with C-number method and super-operator method, the KBES method has several merits. 1) A wide applicable range, KBES method is applicable for any master equation of finite-level system in theory. 2) Compatibility with computer programming, the most crucial procedure is to calculate the exponent of Lindblad operator eFt which needs the diagonalization of F, and all this can be finished by computer. 3) Most mature methods of Schrodinger equation can be used to solve master equation because of the KBES method can transform master equation into Schrodinger-like equation. Then we study the model which two-level qubit is coupled with reservoir under time-varying external field, the corresponding master equation is deduced and solved by KBES method. Furthermore, we analyze the decoherence evolution of density operator and we consider the entanglement evolutions of two uncoupled qubit cases. We find that the external field seriously influences the decoherence process. The off-diagonal elements 10(t) become damply oscillated when the external field exists, and the frequency of oscillate keeps growing along with . Besides, the dynamic evolution of concurrence is also influenced by the external field, which leads to the occurrence of both entanglement sudden death and entanglement sudden birth, while the last ESB phenomenon only happens under the external field. Thus, we thought that one can suppress the decoherence and disentanglement process by exerting suitable time-varying external field on the open system, of course, the suitable external field can also be obtained by our KBES method in theory.

The entanglement evolution between two entangled atoms

The entanglement properties of two entangled atoms interacting with the field under intensity-dependent coupling are studied in detail. It is found that the degree of entanglement between the two atoms changes periodically and undergoes the entanglement sudden death (ESD) and sudden birth at some time. The entanglement properties between the field and the atom inside the cavity are dependent on the photon number. Most interestingly, the entanglement between the field and the atom in the field is influenced significantly by manipulating the atom outside the field.

Dynamical properties of moving atom–atom entanglement and entanglement between two atoms with optical field

Quantum information technology largely relies on a sophisticated and fragile resource, called quantum entanglement, which exhibits a highly nontrivial manifestation of the coherent superposition of the states of composite quantum systems. In this paper, we study the interaction between the general and even coherent fields with moving and stationary two two-level atoms. In this regard, this paper investigates the von Neumann entropy and the atoms–field tangle as a measure of entanglement between the general and even coherent fields with the two atoms. Also, the entanglement between the two atoms using concurrence and negativity during time evolution is discussed. This paper examines the effects of multiphoton transitions and initial state setting on the entanglement for the system under consideration. Finally, the results demonstrate an important phenomenon such as the sudden death and birth of entanglement when the two atoms are initially in entangled states.

Effect of the time-dependent coupling on a superconducting qubit-field system under decoherence: Entanglement and Wehrl entropy

The dynamics of a superconducting (SC) qubit interacting with a field under decoherence with and without time-dependent coupling effect is analyzed. Quantum features like the collapse–revivals for the dynamics of population inversion, sudden birth and sudden death of entanglement, and statistical properties are investigated under the phase damping effect. Analytic results for certain parametric conditions are obtained. We analyze the influence of decoherence on the negativity and Wehrl entropy for different values of the physical parameters. We also explore an interesting relation between the SC-field entanglement and Wehrl entropy behavior during the time evolution. We show that the amount of SC-field entanglement can be enhanced as the field tends to be more classical. The studied model of SC-field system with the time-dependent coupling has high practical importance due to their experimental accessibility which may open new perspectives in different tasks of quantum formation processing.

Dynamics of different entanglement measures of two three-level atoms interacting nonlinearly with a single-mode field

In this paper, we present a model which exhibits two identical $\Xi$-type three-level atoms interacting with a single-mode field with $k$-photon transition in an optical cavity enclosed by a Kerr medium. Considering full nonlinear formalism, it is assumed that the single-mode field, atom-field coupling and Kerr medium are all $f$-deformed. By using the adiabatic elimination method, it is shown that, the Hamiltonian of the considered system can be reduced to an effective Hamiltonian with two two-level atoms and $f$-deformed Stark shift. In spite of the fact that, the system seems to be complicated, under initial conditions which may be prepared for the atoms (coherent superposition of their ground and upper states) and the field (coherent state), the explicit form of the state vector of the entire system is analytically obtained. Then, the entanglement dynamics between different subsystems (i.e. "field-two atoms", "atom-(field+atom)" and "atom-atom") are evaluated through appropriate measures like von Neumann entropy, tangle and concurrence. In addition, the effects of intensity-dependent coupling, deformed Kerr medium, detuning parameter, deformed Stark shift and multi-photon process on the considered entanglement measures are numerically analyzed, in detail. It is shown that the degree of entanglement between subsystems can be controlled by selecting the evolved parameters, suitably. Briefly, the Kerr medium highly decreases the amount of different considered measures of entanglement, especially for two-photon transition. This destructive effect preserves even when all other parameters are present, too. Furthermore, we find that the so-called entanglement sudden death and birth can occur in the atom-atom entanglement.

Effects of detuning and atomic motion parameter on the dynamical behavior of the entanglement between two-level atom and SU(1,1) quantum system

In this paper, we study the dynamics of the atomic inversion and von Neumann entropy for a moving and non-moving two-level atom interacting with multi SU(1,1) quantum system. The wave function and system density matrix using specific initial conditions are obtained. The effects of initial atomic state position and detuning parameters are examined in the absence and presence of the atomic motion effect. Important phenomena such as entanglement sudden death, sudden birth and long-living entanglement are explored during time evolution. The results show that the detuning parameter and excitation number is very useful in generating a high amount of entanglement.

Initial pore pressures under the Lusi mud volcano, Indonesia

The Lusi mud volcano of East Java, Indonesia, remains one of the most unusual geologic disasters of modern times. Since its sudden birth in 2006, Lusi has erupted continuously, expelling more than 90 million cubic meters of mud that has displaced approximately 40,000 people. This study undertakes the first detailed analysis of the pore pressures immediately prior to the Lusi mud volcano eruption by compiling data from the adjacent (150 m away) Banjar Panji-1 wellbore and undertaking pore pressure prediction from carefully compiled petrophysical data. Wellbore fluid influxes indicate that sequences under Lusi are overpressured from only 350 m depth and follow an approximately lithostat-parallel pore pressure increase through Pleistocene clastic sequences (to 1870 m depth) with pore pressure gradients up to [Formula: see text]. Most unusually, fluid influxes, a major kick, connection gases, elevated background gases, and offset well data confirm that high-magnitude overpressures also exist in the Plio-Pleistocene volcanic sequences (1870 to approximately 2833 m depth) and Miocene (Tuban Formation) carbonates, with pore pressure gradients of [Formula: see text]. The varying geology under the Lusi mud volcano poses a number of challenges for determining overpressure origin and undertaking pore pressure prediction. Overpressures in the fine-grained and rapidly deposited Pleistocene clastics have a petrophysical signature typical of disequilibrium compaction and can be reliably predicted from sonic, resistivity, and drilling exponent data. However, it is difficult to establish the overpressure origin in the low-porosity volcanic sequences and Miocene carbonates. Similarly, the volcanics do not have any clear porosity anomaly, and thus pore pressures in these sequences are greatly underestimated by standard prediction methods. The analysis of preeruption pore pressures underneath the Lusi mud volcano is important for understanding the mechanics, triggering, and longevity of the eruption, as well as providing a valuable example of the unknowns and challenges associated with overpressures in nonclastic rocks.

Quantum correlations of two qubits interacting with a macroscopic medium

We consider two particles of spin-1/2 interacting with a one-dimensional N-spin array, which is an exactly solvable model. The dynamics of entanglement and quantum discord (QD) of the spins of the two particles is investigated by regarding the 1D N-spin array as the environment. It is found that although the entanglement may suffers a sudden death and a sudden birth in the evolution, it can neither be generated nor become larger than its initial value. Different from the entanglement dynamics, QD can be amplified, and even be generated by the interaction between particles and the common environment. We also observe that QD decays asymptotically to zero and later experiences a rival when the average number of excitation in the 1D N-spin array becomes larger in the case of nonzero inter-distance between two particles.

Entanglement dynamics for uniformly accelerated two-level atoms

We study, in the paradigm of open quantum systems, the entanglement dynamics of two uniformly accelerated atoms with the same acceleration perpendicular to the separation. The two-atom system is treated as an open system coupled with a bath of fluctuating massless scalar fields in the Minkowski vacuum, and the master equation that governs its evolution is derived. It has been found that, for accelerated atoms with a nonvanishing separation, entanglement sudden death is a general feature when the initial state is entangled, while for those in a separable initial state, entanglement sudden birth only happens for atoms with an appropriate interatomic separation and sufficiently small acceleration. Remarkably, accelerated atoms can get entangled in certain circumstances while the inertial ones in the Minkowski vacuum cannot. A comparison between the results of accelerated atoms and those of static ones in a thermal bath shows that uniformly accelerated atoms exhibit features distinct from those immersed in a thermal bath at the Unruh temperature in terms of entanglement dynamics.