Entanglement dynamics of non-inertial observers in a correlated environment

Effect of decoherence and correlated noise on the entanglement of X-type state of the Dirac fields in the non-inertial frame is investigated. A two qubit X-state is considered to be shared between the partners where Alice is in inertial frame and Rob in an accelerated frame. The concurrence is used to quantify the entanglement of the X-state system influenced by time correlated amplitude damping, depolarizing and bit flip channels. It is seen that amplitude damping and bit flip channels heavily influence the entanglement of the system as compared to the depolarizing channel. It is found possible to avoid entanglement sudden death (ESD) for all the channels under consideration for {\mu}>0.75 for any type of initial state. No ESD behaviour is seen for depolarizing channel in the presence of correlated noise for entire range of decoherence parameter p and Rob's acceleration r. It is also seen that the effect of environment is much stronger than that of acceleration of the accelerated partner. Furthermore, it is investigated that correlated noise compensates the loss of entanglement caused by the Unruh effect.Comment: 18 pages, 6 .eps figures, published online 14 January 2012 in Quantum Information Processing, Springer. arXiv admin note: substantial text overlap with arXiv:1204.1900; and text overlap with arXiv:1105.1216 by other author

Effect of flipping noise on the entanglement dynamics of a 3x3 system

Entanglement dynamics of a qutrit-qutrit system under the influence of global, local and multilocal decoherence introduced by phase flip, trit flip and trit phase flip channels is investigated. The negativity and realignment criterion are used to quantify the entanglement of the system. It is shown that the entanglement sudden death and distibility sudden death can be avoided in the presence of phase flip, trit flip and trit-phase flip environments. It is shown that certain free entangled distillable qutrit states become bound entangled or separable i.e. convert into non-distillable states under different flipping noises. It is also seen that local operations do not have any effect on the entanglement dynamics of the system. Further more, no ESD and DSD is seen for the case of trit flip channel.Comment: 11 pages, 4 eps figure

Decoherence and multipartite entanglement of non-inertial observers

Decoherence effect on multipartite entanglement in non-inertial frames is investigated. GHZ state is considered to be shared between the partners with one partner in inertial frame whereas the other two in accelerated frames. One-tangle and {\pi}-tangles are used to quantify the entanglement of the multipartite system influenced by phase damping and phase flip channels. It is seen that for phase damping channel, entanglement sudden death (ESD) occurs for p>0.5 in the infinite acceleration limit. On the other hand, in case of phase flip channel, ESD behaviour happens around 50% decoherence. It is also seen that entanglement sudden birth (ESB) does occur in case of phase flip channel. Furthermore, it is seen that effect of environment on multipartite entanglement is much stronger than that of the acceleration of non-inertial frames.Comment: 11 pages, 3 .eps figures, Slightly updated to published version in CPL, typos corrected, updated reference

Entanglement dynamics of a qubit-qutrit system in non-inertial frames

The effect of decoherence on a qubit-qutrit system under the influence of global and multilocal decoherence in non-inertial frames is investigated. It is shown that the entanglement sudden death (ESD) can be avoided in non-inertial frames in the presence of dephasing and bit-trit phase flip channels for entire range of decoherence. However, ESD behaviour is seen for higher level of decoherence in case of phase flip and bit-trit flip channels. Irrespective of the entanglement degradation caused by the Unruh effect, no ESD occurs for the dephasing environment. Furthermore, flipping channels have approximately similar effect on the entanglement of the hybrid system.Comment: 10 pages, 3 eps figures. arXiv admin note: substantial text overlap with arXiv:1101.398

Decoherence dynamics of geometric measure of quantum discord and measurement-induced nonlocality for noninertial observers at finite temperature

Quantum discord quantifies the total non-classical correlations in mixed states. It is the difference between total correlation, measured by quantum mutual information, and the classical correlation. Another step forward towards the quantification of quantum discord was by Dakic, Vedral, and Brukner [Phys. Rev. Lett. 105,190502 (2010)] who introduced the geometric measure of quantum discord (GMQD) and derived an explicit formula for a two-qubit state. Recently, Luo and Fu [Phys. Rev. Lett. 106, 120401 (2011)] introduced measurement-induced nonlocality (MIN) as a measure of nonlocality for a bipartite quantum system. The dynamics of GMQD is recently considered by Song et al. [arXiv: quant/ph.1203.3356] and Zhang et al. [Eur. Phys. J. D 66, 34 (2012)] for inertial observers. However, the topic requires due attention in noninertial frames, particularly, from the perspective of MIN. Here I consider X-structured bipartite quantum system in noninertial frames and analyze the decoherence dynamics of GMQD and MIN at finite temperature. The dynamics under the influence of amplitude damping, depolarizing and phase flip channels is discussed. It is worth-noting that initial state entanglement plays an important role in bipartite states. It is possible to distinguish the Bell, Werner and general type initial quantum states using GMQD. Sudden transition in the behaviour of GMQD and MIN occurs depending upon the mean photon number of the local environment. The transition behaviour disappears for larger values of n, i.e. n>0.3. It becomes more prominent, when environmental noise is introduced in the system. ......Comment: 22 pages, 6 .eps figures, 1 table, Accepted for Publication in Journal of Quantum Information Processin

Proper curvature symmetry in non-static cylindrically symmetric Lorentzian manifolds

We considered the most general form of non-static cylindrically symmetric space-times for studying proper curvature symmetry by using the rank of the 6X6 Riemann matrix and direct integration techniques. Studying proper curvature symmetry in each case of the above space-times it is shown that when the above space-times admit proper curvature symmetry, they form an infinite dimensional vector space.Comment: 23 page

Noise effects in a three-player Prisoner's Dilemma quantum game

We study the three-player Prisoner's Dilemma game under the effect of decoherence and correlated noise. It is seen that the quantum player is always better off over the classical players. It is also seen that the game's Nash equilibrium does not change in the presence of correlated noise in contradiction to the effect of decoherence in multiplayer case. Furthermore, it is shown that for maximum correlation the game does not behave as a noiseless game and the quantum player is still better off for all values of the decoherence parameter p which is not possible in the two-player case. In addition, the payoffs reduction due to decoherence is controlled by the correlated noise throughout the course of the game.Comment: 18 pages, 5 ps figures, 1 tabl

Quantum Model of Bertrand Duopoly

We present the quantum model of Bertrand duopoly and study the entanglement behavior on the profit functions of the firms. Using the concept of optimal response of each firm to the price of the opponent, we found only one Nash equilibirum point for maximally entangled initial state. The very presence of quantum entanglement in the initial state gives payoffs higher to the firms than the classical payoffs at the Nash equilibrium. As a result the dilemma like situation in the classical game is resolved.Comment: 9 pages, 2 .eps figur

Noisy non-transitive quantum games

We study the effect of quantum noise in 3 by 3 entangled quantum games. By considering different noisy quantum channels we analyze that how a two-player, three-strategy Rock-Scissor-Paper game is influenced by the quantum noise. We consider the winning non-transitive strategies R, S and P such as R beats S, S beats P, and P beats R. The game behaves as a noiseless game for maximum value of the quantum noise parameter. It is seen that Alice's payoff is heavily influenced by the depolarizing noise as compared to the amplitude damping noise. Depolarizing channel causes a monotonic decrease in players payoffs as we increase the amount of of quantum noise. In case of amplitude damping channel, the Alice's payoff function reaches its minimum for alpha=0.5 and is symmetrical. This means that larger values of quantum noise influence the game weakly. On the other hand, phase damping channel does not influence the game's payoff. Furthermore, the game's Nash equilibrium and non-transitive character of the game are not affected under the influence of quantum noise.Comment: 18 pages, 6 .eps figures, 1 .eps tabl

Classification of Kantowski-Sachs and Bianchi Type III space-times according to their proper conformal vector fields

We investigate proper conformal vector fields in non conformally flat Kantowski-Sachs and Bianchi type III space-times using direct integration technique. Using the above mentioned technique we show that very special classes of the above space-times admit proper conformal vector fields.Comment: 5 page