Manipulation of entanglement sudden death in an all-optical setup

Abstract

The unavoidable and irreversible interaction between an entangled quantum system and its environment causes decoherence of the individual qubits as well as degradation of the entanglement between them. Entanglement sudden death (ESD) is the phenomenon wherein disentanglement happens in finite time even when individual qubits decohere only asymptotically in time due to noise. Prolonging the entanglement is essential for the practical realization of entanglement-based quantum information and computation protocols. For this purpose, the local NOT operation in the computational basis on one or both qubits has been proposed. Here, we formulate an all-optical experimental set-up involving such NOT operations that can hasten, delay, or completely avert ESD, all depending on when it is applied during the process of decoherence. Analytical expressions for these are derived in terms of parameters of the initial state's density matrix, whether for pure or mixed entangled states. After a discussion of the schematics of the experiment, the problem is theoretically analyzed, and simulation results of such manipulations of ESD are presented

Entanglement sudden death and revival in quantum dark-soliton qubits

“…For large separations, ESD occurs at t death ∼ 2 ms due to the balanced population of ρ eg and ρ −− whereas, for the mixed initial state, the dark period occurs for ∼ 3.6 ms. Prolonging entanglement is essential for practical realization of quantum information and computation protocols based on entanglement. Therefore, the dark period of entanglement can be delayed or averted by carrying out local unitary operation on qubits [50,51].…”

Phonon-mediated quantum discord in dark solitons

“…The phenomenon of sudden death and revival for quantum discord occurs at α ≥ 0.80. By estimating the death and revival time with the use of few kHz of chemical potential µ, the dark period (revivalsudden death) appears to be 10ms which can be averted or delayed by carrying out some local unitary operators on DS qubits [50,51].…”

Verifying the Survival of Time-Energy Entanglement Through Tissue

“…Multipartite entangled states are particularly susceptible to decoherence [26], as the degree of entanglement degrades super linearly with loss and interactions with the environment. In fact, entanglement breaking can occur faster than one would expect with environmentally-induced decoherence as found in entanglement "sudden death" [27][28][29][30].…”