It is shown that the Einstein-Podolsky-Rosen (EPR) correlations for arbitrary spin s and the Greenberger-Horne-Zeilinger (GHZ) correlations for three particles can be described by nonlocal joint and conditional quantum probabilities. The nonlocality of these probabilities makes the Bell inequalities void. A description that exhibits the relation between the randomness and the nonlocality of entangled correlations is introduced. Entangled EPR and GHZ correlations are studied using the Gibbs-Shannon entropy. The nonlocal character of the EPR correlations is tested using the information Bell inequalities. Relations between the randomness, the nonlocality, and the entropic information for the EPR and the GHZ correlations are established and discussed.
The Einstein-Podolsky-Rosen (EPR) paradox gives an argument for the incompleteness of quantum mechanics based on the premises of local realism. A general view is that the argument is compromised, because EPR's premises are falsified by Greenberger-Horne-Zeilinger (GHZ) and Bell experiments. In this paper, we present an EPR argument based on premises not falsifiable by these experiments. We propose macroscopic EPR and GHZ experiments using spins
Sθ defined by two macroscopically distinct states. The analyzers that realize the unitary operations
Uθ determining the measurement settings
θ are devices that create macroscopic superposition states. For a system with two macroscopically distinct states available, macroscopic realism (MR) posits a predetermined outcome for a measurement
Sθ distinguishing between the states. Deterministic macroscopic realism (dMR) posits MR for the system prior to the interaction
Uθ. Weak macroscopic realism (wMR) posits MR for the system after
Uθ, at the time
tf (when the system is prepared for a final "pointer" measurement), the outcome of
Sθ not being changed by interactions that might occur at a remote system
B. The premise also posits that if the outcome for
SθA of a system
A can be predicted by a pointer measurement on a system
B defined after the interaction fixing the setting at
B, then the outcome for
SθA is determined at this time. The GHZ predictions negate dMR but are consistent with wMR. Yet, an EPR paradox arises based on wMR for the set-up proposed by Schrödinger, where one measures two complementary spins simultaneously, "one by direct, the other by indirect" measurement. We revisit the original EPR paradox and find similarly that an EPR argument can be based on a weak form of local realism not falsifiable by GHZ or Bell tests.
Two schemes, using respectively the single three-particle maximal Greenberger-Horne-Zeilinger (GHZ) state and the two Einstein-Podolsky-Rosen (EPR) states as quantum channels, for deterministic teleportation of arbitrary three-particle GHZ state are proposed. These schemes are also generalized into the case of teleportation of arbitrary n-particle GHZ state (n≥4). The fidelity of teleportation when the quantum channels are affected by noise is discussed. It is found that when using single three-particle GHZ state which is affected by noise as quantum channel, the fidelity of teleportation is only related to the entanglement of the channel. However, when using two EPR states which is affected by noise as quantum channels, the fidelity of teleportation is related to the entanglement of both the channels and the unknown state to be delivered. Compared with previous proposals, our schemes require a reduced number of entangled states as quantum channels to achieve the same task.