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Urbasi Sinha (Raman Research Institute, Bangalore)
Date & Time
Mon, 16 November 2020, 15:30 to 17:00

Quantum state tomography (QST) has been the traditional method for characterization of an unknown state. Recently, many direct measurement methods have been implemented to reconstruct the state in a resource efficient way. Here we present an interferometric method, in which any qubit state, whether mixed or pure, can be inferred from the visibility, phase shift, and average intensity of an interference pattern using a single-shot measurement—hence, we call it quantum state interferography. This provides us with a “black box” approach to quantum state estimation, wherein, between the incidence and extraction of state information, we are not changing any conditions within the setup, thus giving us a true single shot estimation of the quantum state. An extension of the scheme to pure states involving d−1 interferograms for d-dimensional systems (qudits) is also presented. The scaling gain is even more dramatic in the qudit scenario for our method, where, in contrast, standard QST, scales roughly as d2.