Uncertainty relations for the realization of macroscopic quantum superpositions and EPR paradoxes

Uncertainty relations for the realization of macroscopic quantum superpositions and EPR paradoxes

Towards an Einstein–Podolsky–Rosen paradox between two macroscopic atomic ensembles at room temperature

Experiments have reported the entanglement of two spatially separated macroscopic atomic ensembles at room temperature (Krauter et al 2011 Phys. Rev. Lett. 107 080503; Julsgaard et al 2001 Nature 413 400). We show how an Einstein–Podolsky–Rosen (EPR) paradox is realizable with this experiment. Our proposed test involves violation of an inferred Heisenberg uncertainty principle, which is a suffi...

Anomalous lack of decoherence of the macroscopic quantum superpositions based on phase-covariant quantum cloning.

We show that all macroscopic quantum superpositions (MQS) based on phase-covariant quantum cloning are characterized by an anomalous high resilence to the decoherence processes. The analysis supports the results of recent MQS experiments and leads to conceive a useful conjecture regarding the realization of complex decoherence-free structures for quantum information, such as the quantum computer.

Criteria for generalized macroscopic and mesoscopic quantum coherence

We consider macroscopic, mesoscopic, and “S-scopic” quantum superpositions of eigenstates of an observable and develop some signatures for their existence. We define the extent, or size S of a superposition, with respect to an observable x̂, as being the range of outcomes of x̂ predicted by that superposition. Such superpositions are referred to as generalized S-scopic superpositions to distingui...

Macroscopic Local Realism Incompatible with Quantum Mechanics: Failure of Local Realism where Measurements give Macroscopic Uncertainties

We show that quantum mechanics predicts a contradiction with local hidden variable theories for photon number measurements which have limited resolving power, to the point of imposing an uncertainty in the photon number result which is macroscopic in absolute terms. We show how this can be interpreted as a failure of a new premise, macroscopic local realism. Bell [1] in 1966 showed that the pre...