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Updated: Mar 29, 2026
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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
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Entanglement and Private Information in Many-Body Thermal States.
Samuel J Garratt1, Max McGinley2
1University of California, Department of Physics, Berkeley, California 94720, USA.
Physical Review Letters
|March 27, 2026
Summary
Quantum cryptography links entanglement in mixed states to correlations. Entangled states can distill private keys, revealing system entanglement via environmental eavesdropping information and linear response. Canonical ensembles remain entangled at all finite temperatures.
Area of Science:
- Quantum Information Science
- Condensed Matter Physics
- Quantum Cryptography
Background:
- Entanglement is a key quantum resource, crucial for quantum information processing.
- Characterizing entanglement in complex many-body systems, especially mixed states, remains a significant challenge.
- Quantum cryptography offers tools to define and detect entanglement through secure key distribution.
Purpose of the Study:
- To establish a connection between entanglement in many-body mixed states and standard correlation functions using quantum cryptography concepts.
- To develop a method for detecting entanglement by analyzing information accessible to an eavesdropper and the system's linear response.
- To investigate the role of symmetries in preserving entanglement against environmental decoherence.
Main Methods:
- Utilizing concepts from quantum cryptography to link entanglement to correlation functions.
- Deriving a relationship between eavesdropper information and linear response for thermal states.
- Analyzing the implications of density matrix symmetries on hidden correlations.
Main Results:
- Demonstrated that a system's ability to distill private keys implies its entangled state.
- Derived a direct relation between eavesdropper information and linear response for thermal states, enabling entanglement detection.
- Showed that strong symmetries in a density matrix guarantee correlations hidden from the environment.
Conclusions:
- Spatial correlations can serve as a new experimental probe for detecting entanglement across diverse physical systems.
- While grand canonical ensembles become separable above a critical temperature, canonical ensembles exhibit entanglement at all finite temperatures.
- The findings provide novel insights into the nature of entanglement in mixed states and its resilience to environmental interactions.
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