Revealing hidden Einstein-Podolsky-Rosen nonlocality

Area of Science:

• Quantum Information Science
• Quantum Foundations
• Quantum Optics

Background:

• Quantum steering is a key aspect of quantum nonlocality, closely linked to the Einstein-Podolsky-Rosen (EPR) paradox.
• It represents a form of quantum correlation intermediate between Bell nonlocality and entanglement.
• Previous detection in continuous variable systems relied on violating Reid's EPR inequality, using inferred variances of complementary observables.

Purpose of the Study:

• To propose and experimentally validate a novel criterion for detecting EPR steering based on entropy functions.
• To demonstrate the superiority of the entropic criterion over the variance-based inequality for identifying EPR steering.

Main Methods:

• Development of a new EPR steering detection criterion utilizing entropy functions.
• Experimental testing of the proposed entropic criterion in a continuous variable system.
• Comparison of the entropic criterion's performance against the established variance-based Reid's EPR inequality.

Main Results:

• The proposed entropic criterion successfully identified EPR steering in the experimental results.
• The variance-based criterion failed to detect EPR steering for the same experimental data.
• The entropic criterion proved to be more powerful than the variance inequality for detecting EPR steering.

Conclusions:

• The novel entropic criterion offers a more sensitive tool for detecting quantum steering.
• This advancement expands the range of quantum states and systems where EPR steering can be observed.
• The findings contribute to a deeper understanding of quantum nonlocality and its manifestations.