Extreme nonlocality with one photon

Abstract

Quantum nonlocality is typically assigned to systems of two or more well separated particles, but nonlocality can also exist in systems consisting of just a single particle, when one considers the subsystems to be distant spatial field modes. Single particle nonlocality has been confirmed experimentally via a bipartite Bell inequality. In this paper, we introduce an N -party Hardy-like proof of impossibility of local elements of reality and a Bell inequality for local realistic theories for a single particle superposed symmetrical over N spatial field modes (i.e., a N qubit W state). We show that, in the limit of large N , the Hardy-like proof effectively becomes an all-versus nothing (or GHZ-like) proof, and the quantum-classical gap of the Bell inequality tends to be same of the one in a three-particle GHZ experiment. We detail how to test the nonlocality in realistic systems. arXiv:0911.0770v3 [quant-ph]

Nonlocality ofWand Dicke states subject to losses

“…Moreover, the nonlocality of symmetric pure qubit states is elegantly captured by a single Bell inequality [20]. The nonlocality of the simplest Dicke states, featuring a single excitation (the so-called W -states), has been widely discussed [21][22][23][24][25][26][27], in particular in the context of optical Bell tests based on single photon entanglement [28][29][30]. Notably, the possibility of self-testing the W state has been recently demonstrated [31,32].…”

Quantum Entanglement Concentration Based on Nonlinear Optics for Quantum Communications

“…After the photons pass through the QND1, if Alice picks up the phase shift, θ, the remaining state essentially will be Equation (69). Certainly, the similar step is performed by Charlie.…”

“…Experimental schemes to generate these W states have been already proposed [62][63][64][65]. It has been proven that the W state is robust to decoherence in the noisy environment [66][67][68], and it displays an effective all-versus-nothing nonlocality, as the number of N delocalizations of the single particle goes up [69]. Especially, Gottesman et al discussed an approach to building interferometric telescopes using such W states [70].…”

Deterministic teleportation using single-photon entanglement as a resource

“…Proposals [9][10][11][12][13][14][15][16][17][18][19][20] and experiments [21][22][23] demonstrating single-photon entanglement, nonlocality, and entanglement purification have been performed, but the prospect of teleportation using single-photon entanglement as the quantum resource has still not been regarded on equal footing with teleportation schemes involving "carrier" particles in each of the entangled modes.…”