Adaptive Quantum State Tomography Improves Accuracy Quadratically

D. H. Mahler, Lee A. Rozema, Ardavan Darabi, Christopher Ferrie, Robin Blume-Kohout, and A. M. Steinberg

Phys. Rev. Lett. 111, 183601 – Published 29 October 2013

Abstract

We introduce a simple protocol for adaptive quantum state tomography, which reduces the worst-case infidelity [ $1 - F (\hat{ρ}, ρ)$ ] between the estimate and the true state from $O (1 / \sqrt{N})$ to $O (1 / N)$ . It uses a single adaptation step and just one extra measurement setting. In a linear optical qubit experiment, we demonstrate a full order of magnitude reduction in infidelity (from 0.1% to 0.01%) for a modest number of samples ( $N \approx 3 \times 10^{4}$ ).

Received 2 March 2013

DOI:https://doi.org/10.1103/PhysRevLett.111.183601

Authors & Affiliations

D. H. Mahler^1,2,*, Lee A. Rozema^1,2, Ardavan Darabi^1,2, Christopher Ferrie³, Robin Blume-Kohout⁴, and A. M. Steinberg^1,2

¹Department of Physics, Centre for Quantum Information and Quantum Control and Institute for Optical Sciences, University of Toronto, 60 St. George Street, Toronto, Ontario M5S 1A7, Canada
²Canadian Institute for Advanced Research, Toronto, Ontario M5G1Z8, Canada
³Center for Quantum Information and Control, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
⁴Sandia National Laboratories, Advanced Device Technologies (01425), Albuquerque, New Mexico 87185, USA

^*dmahler@physics.utoronto.ca

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Vol. 111, Iss. 18 — 1 November 2013

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