Nonlocal single particle steering generated through single particle entanglement

Abstract

In 1927, at the Solvay conference, Einstein posed a thought experiment with the primary intention of showing the incompleteness of quantum mechanics; to prove it, he employed the instantaneous nonlocal effects caused by the collapse of the wavefunction of a single particle—the spooky action at a distance–, when a measurement is done. This historical event preceded the well-know Einstein–Podolsk–Rosen criticism over the incompleteness of quantum mechanics. Here, by using the Stern–Gerlach experiment, we demonstrate how the instantaneous nonlocal feature of the collapse of the wavefunction together with the single-particle entanglement can be used to produce the nonlocal effect of steering, i.e. the single-particle steering. In the steering process Bob gets a quantum state depending on which observable Alice decides to measure. To accomplish this, we fully exploit the spreading (over large distances) of the entangled wavefunction of the single-particle. In particular, we demonstrate that the nonlocality of the single-particle entangled state allows the particle to “know” about the kind of detector Alice is using to steer Bob’s state. Therefore, notwithstanding strong counterarguments, we prove that the single-particle entanglement gives rise to truly nonlocal effects at two faraway places. This opens the possibility of using the single-particle entanglement for implementing truly nonlocal task.

A Protocol for Conversion of Path-Spin to Spin-Spin Quantum Entanglement

“…The term 'steering' in quantum mechanics refers to the ability of one observer (Alice) to influence the state of a distant particle (Bob) through measurements made on her own particle. This phenomenon showcases the nonlocal nature of quantum entanglement [39]. It has been established that two successive SG experiments produce quantum nonlocality and quantum steering [40], whose relations with entanglement put a prominent footprint on our usual understanding of the experiment as a natural consequence of considering quantum correlations.…”

Thirty Years in Silicon Photonics: A Personal View

“…Values that span from 2.5% up to 30.1% are observed for different levels of description of the setup (Figure 14I) [211]. Moreover, it has been reported that SPE is a resource for other kind of quantum information applications, for example quantum key distribution [223,224], quantum teleportation [225], state swapping [226], entanglement concentration [227], and single-photon steering [228,229].…”