A new paper presents evidence of quantum entanglement (normally existing only in extremely fragile, environmentally-isolated, few-particle systems) in a high-temp many-particle system:
"Evidence for entanglement at high temperatures in an engineered molecular magnet " http://iopscience.iop.org/0295-5075/100/5/50001 [[ABSTRACT: The molecular compound [Fe2(μ2-oxo)(C3H4N2)6(C2O4)2] was designed and synthesized for the first time and its structure was determined using single-crystal X-ray diffraction. The magnetic susceptibility of this compound was measured from 2 to 300 K. The analysis of the susceptibility data using protocols developed for other spin singlet ground-state systems indicates that the quantum entanglement would remain at temperatures up to 732 K, significantly above the highest entanglement temperature reported to date. The large gap between the ground state and the first-excited state (282 K) suggests that the spin system may be somewhat immune to decohering mechanisms. Our measurements strongly suggest that molecular magnets are promising candidate platforms for quantum information processing.]] [[EXCERPT: Therefore, the study of entanglement in solid-state physics is of great relevance to the area of quantuminformation, since many proposals of quantum processors are solid-state based [20]. The recent demonstration that entanglement can change the thermodynamic properties of solids, such as magnetic susceptibility [17,18], shows that entanglement can be related to significant macroscopic effects. Hence, this subject establishes an interesting connection between quantum information theory and condensed-matter physics, because magnetization [37], heat capacity [38], and internal energy [39] can also be used to reveal spin entanglement among constituents of a solid. Quantum entanglement at elevated temperatures has been studied in several physical systems and the recent work by Vedral [40] summarizes this scenario. In that work it is recognized that some molecular magnets remain entangled at surprisingly high temperatures.]] Since some papers have shown that entanglement is a resource that can be used to extract more work from heat than is possible in unentangled systems, this paper may be of interest. Full pdf is available with free account sign-up. - Lou Pagnucco
