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Tighter quantum uncertainty relations following from a general probabilistic bound

Fröwis, Florian and Schmied, Roman and Gisin, Nicolas. (2015) Tighter quantum uncertainty relations following from a general probabilistic bound. Physical Review A , 92 (1). 012102.

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Official URL: http://edoc.unibas.ch/53924/

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Abstract

Uncertainty relations (URs) such as the Heisenberg-Robertson or the time-energy UR are often considered to be hallmarks of quantum theory. Here, a simple derivation of these URs is presented based on a single classical inequality from estimation theory, a Cramér-Rao-like bound. The Heisenberg-Robertson UR is then obtained by using the Born rule and the Schrödinger equation. This allows a clear separation of the probabilistic nature of quantum mechanics from the Hilbert space structure and the dynamical law. It also simplifies the interpretation of the bound. In addition, the Heisenberg-Robertson UR is tightened for mixed states by replacing one variance by the quantum Fisher information. Thermal states of Hamiltonians with evenly gapped energy levels are shown to saturate the tighter bound for natural choices of the operators. This example is further extended to Gaussian states of a harmonic oscillator. For many-qubit systems, we illustrate the interplay between entanglement and the structure of the operators that saturate the UR with spin-squeezed states and Dicke states.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Experimentelle Nanophysik (Treutlein)
UniBasel Contributors:Schmied, Roman
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Physical Society
ISSN:2469-9926
e-ISSN:2469-9934
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
Identification Number:
Last Modified:20 Feb 2017 15:31
Deposited On:20 Feb 2017 15:31

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