Środowiskowe Seminarium z Informacji i Technologii Kwantowych

Quantum metrology under the idealistic assumption of no decoherenceoffers enhancement of measurement precision that grows withoutrestraint with the number of particles involved. Motivated bypractical applications, we propose tools for quantifying theattainable quantum enhancement based on the geometry of quantumchannels and semi-definite programming that account for the inevitableimpact of the noise. As a result we obtain a simple and direct methodyielding bounds that interpolate between the quantum enhanced scalingcharacteristic for small number of particles and the asymptoticregime, where quantum enhancement amounts to a constant factorimprovement.