M. K. Khan

Open Quantum Systems in Noninertial Frames

We study the effects of decoherence on the entanglement generated by the Unruh effect in noninertial frames by using phase flip, phase damping and depolarizing channels. It is shown that decoherence strongly influences the initial state entanglement. Entanglement sudden death can occur irrespective of the acceleration of the noninertial frame under the action of phase flip and phase damping channels. It is investigated that an early sudden death occurs for large acceleration under the depolarizing environment. Moreover, entanglement increases for a highly decohered phase flip channel.

Decoherence and entanglement degradation of a qubit-qutrit system in non-inertial frames

We study the effect of decoherence on a qubit-qutrit system under the influence of global, local and multilocal decoherence in non-inertial frames. We show that the entanglement sudden death can be avoided in non-inertial frames in the presence of amplitude damping, depolarizing and phase damping channels at lower level of decoherence. However, degradation of entanglement is seen due to Unruh effect. It is seen that for lower values of decoherence, the depolarizing channel heavily degrades the entanglement as compared to the amplitude damping and phase damping channels. Entanglement sudden birth is also seen in case of depolarizing channel. However, for higher values of decoherence parameters, amplitude damping channel dominantly degrades the entanglement of the hybrid system. Entanglement sudden death is not seen for any value of acceleration of the accelerated observer “Rob” in case of phase damping channel. Further more, a symmetrical behaviour of negativity is seen for depolarizing channel.

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.

Noise effects in a three-player prisoner's dilemma quantum game

We study the three-player prisoners dilemma game under the effect of decoherence and correlated noise. It is seen that the quantum player is always better off than the classical players. It is also seen that the games Nash equilibrium does not change in the presence of correlated noise in contradiction to the effect of decoherence in the 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.

The effect of quantum memory on quantum games

We study quantum games with correlated noise through a generalized quantization scheme. We investigate the effects of memory on quantum games, such as Prisoners Dilemma, Battle of the Sexes and Chicken, through three prototype quantum-correlated channels. It is shown that the quantum player enjoys an advantage over the classical player for all nine cases considered in this paper for the maximally entangled case. However, the quantum player can also outperform the classical player for subsequent cases that can be noted in the case of the Battle of the Sexes game. It can be seen that the Nash equilibria do not change for all the three games under the effect of memory.

ENVIRONMENT-ASSISTED QUANTUM MINORITY GAMES

The effect of entanglement and correlated noise in a four-player quantum Minority game is investigated. Different time correlated quantum memory channels are considered to analyze the Nash equilibrium payoff of the 1st player. It is seen that the Nash equilibrium payoff is substantially enhanced due to the presence of correlated noise. The behaviour of damping channels (amplitude damping and phase damping) is approximately similar. However, bit-phase flip channel heavily influences the minority game as compared to other channels in the presence of correlated noise. On the other hand, phase flip channel has a symmetrical behaviour around 50% noise threshold. The significant reduction in payoffs due to decoherence is well compensated due to the presence of correlated noise. However, the Nash equilibrium of the game does not change in the presence of noise. It is seen that in case of generalized amplitude damping channel, entanglement plays a significant role at lower level of decoherence. The channel has less dominant effects on the payoff at higher values of decoherence. Furthermore, amplitude damping and generalized amplitude damping channels have almost comparable effects at lower level of decoherence

Distinguishing quantum channels via magic squares game

(p<0.5)

Quantum Monty Hall problem under decoherence

. Therefore, the game deserves careful study during its implementation due to prominent role of noise for different channels.

Non-Maximal Tripartite Entanglement Degradation of Dirac and Scalar Fields in Non-Inertial Frames

We study the effect of quantum memory in magic squares game when played in quantum domain. We consider different noisy quantum channels and analyze their influence on the magic squares quantum pseudo-telepathy game. We show that the probability of success can be used to distinguish the quantum channels. It is seen that the mean success probability decreases with increase of quantum noise. Where as the mean success probability increases with increase of quantum memory. It is also seen that the behaviour of amplitude damping and phase damping channels is similar. On the other hand, the behaviour of depolarizing channel is similar to the flipping channels. Therefore, the probability of success of the game can be used to distinguish the quantum channels.

Entanglement of Open Quantum Systems in Noninertial Frames

We study the effect of decoherence on quantum Monty Hall problem under the influence of amplitude damping, depolarizing, and dephasing channels. It is shown that under the effect of decoherence, there is a Nash equilibrium of the game in case of depolarizing channel for Alices quantum strategy. Whereas in case of dephasing noise, the game is not influenced by the quantum channel. For amplitude damping channel, Bobs payoffs are found symmetrical about a decoherence of 50% and the maximum occurs at this value of decoherence for his classical strategy. However, it is worth-mentioning that in case of depolarizing channel, Bobs classical strategy remains always dominant against any choice of Alices strategy.