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Updated: Feb 17, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
State-Independent Uncertainty Relations and Entanglement Detection in Noisy Systems
René Schwonnek1, Lars Dammeier1, Reinhard F Werner1
1Leibniz Universität Hannover-Institut für Theoretische Physik, Hannover 30167, Germany.
Abstract:
Quantifying quantum mechanical uncertainty is vital for the increasing number of experiments that reach the uncertainty limited regime. We present a method for computing tight variance uncertainty relations, i.e., the optimal state-independent lower bound for the sum of the variances for any set of two or more measurements. The bounds come with a guaranteed error estimate, so results of preassigned accuracy can be obtained straightforwardly. Our method also works for postive-operator-valued measurements. Therefore, it can be used for detecting entanglement in noisy environments, even in cases where conventional spin squeezing criteria fail because of detector noise.
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