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arXiv · 1607.05723

Discriminating between Lüders and von Neumann measuring devices: An NMR investigation

C. S. Sudheer Kumar·Abhishek Shukla·T. S. Mahesh
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Abstract

Measurement of an observable on a quantum system involves a probabilistic collapse of the quantum state and a corresponding measurement outcome. Lüders and von Neumann state update rules attempt to describe the above phenomenological observations. These rules are identical for a nondegenerate observable, but differ for a degenerate observable. While Lüders rule preserves superpositions within a degenerate subspace under a measurement of the corresponding degenerate observable, the von Neumann rule does not. Recently Hegerfeldt and Mayato [Phys. Rev. A, 85, 032116 (2012)] had formulated a protocol to discriminate between the two types of measuring devices. Here we have reformulated this protocol for quantum registers comprising of system and ancilla qubits. We then experimentally investigated this protocol using nulear spin systems with the help of NMR techniques, and found that Lüders rule is favoured.

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C. S. Sudheer Kumar, Abhishek Shukla, T. S. Mahesh. 2016-08-05. Discriminating between Lüders and von Neumann measuring devices: An NMR investigation. https://doi.org/10.1016/j.physleta.2016.09.004

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