671 research outputs found
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
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