Two interferometric complementarities

Paradox in Wave-Particle Duality

“…(2) In the context of the double-slit welcher-weg experiments, the original formulation of the BPC dictates that in a particular experimental configuration, "the observation of an interference pattern and the acquisition of which-way information are mutually exclusive". (4)(5)(6)(7)(8)(9) Experiments have revealed the possibility of partial fringe visibility and partial which-way-information within strict limitations, and many experiments have backed this validation of BPC. (10)(11)(12)(13)(14) What these experiments have in 3 common, however, is the fact that they provide information by measurement techniques which ultimately perturb the wavefunction.…”

An Approach To “Quantumness” In Coherent Control

“…For any two-path interferometer, it can further be shown [95][96][97][98][99] that the complementarity between wave and particle behavior is quantitatively manifest in the duality relation…”

“…(64b). Note that since the duality relation (56) holds for all measurements O R , it specifically holds for the measurements that maximize the acquired WWI, K(O R ) = D R , and restore the most fringe contrast, V(O R ) = C R , respectively [94,99].…”

Proposal for direct measurement of concurrence via visibility in a cavity QED system

“…The scheme works for any arbitrary pure state of a two-qubit cavity system even when no prior knowledge about the state is given. The scheme derives from the realization that the concurrence coincides with the two-particle visibility under suitable interferometric setups, which in turn derives from previous theoretical investigations [19,20,24,25,26,27,28,29,30] that revealed complementarity between one-particle and twoparticle interferences and consequently intimate relations between two-particle interference and the concurrence.The scheme for single-particle interference. A twolevel atom prepared in its ground state passes successively through cavity A, a dispersive interaction region and cavity B.…”

“…The question naturally arises whether entanglement can be estimated without having to fully reconstruct the unknown state. It has been shown that the answer to this question is yes at least for the case of pure two-qubit states [7,8], although, even in this case, more than one observable need to be measured.In recent years, several methods [9,10,11,12,13] have been proposed for detecting and measuring entanglement without a full reconstruction of the state; e.g., the method [9] based on the technique of minimal and optimal tomography [14,15] performed on one of the entangled pair, the method [10] based on entanglement witness [16,17] which was realized experimentally [18], the method [11,12] based on PPT criterion [1,2], and the method [13] based on two-particle interferometry [19,20]. These methods, although much simpler than the full state reconstruction, are not completely free of experimental difficulties, as they require either controlled unitary operations or some prior knowledge about the quantum state in question, or they can detect entanglement but not measure its amount.…”