Abstract
During the last few decades, considerable advances in quantum information theory have shown deep existing connections between quantum correlation effects (like entanglement and quantum discord) and thermodynamics. Here the concept of conditional entropy plays a considerable role. In contrast to the classical case, quantum conditional entropy can take negative values. This counter-intuitive feature, already well understood in the context of information theory, was recently shown theoretically to also have a physical meaning in quantum thermodynamics [del Rio et al. Nature 2011, 474, 61]. Extending this existing work, here we provide evidence of the significance of negative conditional entropy in a concrete experimental context: Incoherent Neutron Scattering (INS) from protons of H2 in nano-scale environments; e.g., in INS from H2 in C-nanotubes, the data of the H2 translational motion along the nanotube axis seems to show that the neutron apparently scatters from a fictitious particle with mass of 0.64 atomic mass units (a.m.u.)—instead of the value of 2 a.m.u. as conventionally expected. An independent second experiment confirms this finding. However, taking into account the possible negativity of conditional entropy, we explain that this effect has a natural interpretation in terms of quantum thermodynamics. Moreover, it is intrinsically related to the number of qubits capturing the interaction of the two quantum systems H2 and C-nanotube. The considered effect may have technological applications (e.g., in H-storage materials and fuel cells).
Highlights
During the last few decades, considerable advances in quantum information theory have shown deep existing connections between quantum correlation effects and thermodynamics
Taking into account the possible negativity of conditional entropy, we explain that this effect has a natural interpretation in terms of quantum thermodynamics
We may emphasize the significance of the counter-intuitive Elitzur-Vaidman effect [20] concerning interaction-free measurements (IFM, popularly known as “bomb tester”), which revealed the ability to obtain experimental information about an object’s presence in some position of one path of a Mach-Zehnder interferometer (MZI), without ever “touching” it
Summary
During the last few decates, theoretical advances in (non-relativistic) quantum mechanics have provided novel insights into several physical and technological fields, and have allowed us to predict new effects and to invent new technological applications. Quantum correlations between non-identical particles (e.g., protons and neutrons) are all but unknown in most fields, like, e.g., chemistry, molecular biology and applied material sciences, but they play a central role here They are unknown in standard non-relativistic neutron scattering theory [8,9,10,11]. The focus of this paper is on the experimental relevance of general theory for concrete scattering experiments—interpretational issues concerning basic quantum entities and/or purely theoretical derivations play only a minor role here. This viewpoint was unacceptable for the overwhelming majority of physicists in the last century In this context, we may emphasize the significance of the counter-intuitive Elitzur-Vaidman effect [20] concerning interaction-free measurements (IFM, popularly known as “bomb tester”), which revealed the ability to obtain experimental information about an object’s presence in some position of one path of a Mach-Zehnder interferometer (MZI), without ever “touching” it. Many computer-science theoreticians believe that such a quantum supremacy does not exist at all—i.e., that QIT does not provide fundamentally more computational power than classical IT
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