3,016 research outputs found
Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath
A single-molecule magnet placed in a magnetic field perpendicular to its
anisotropy axis can be truncated to an effective two-level system, with easily
tunable energy splitting. The quantum coherence of the molecular spin is
largely determined by the dynamics of the surrounding nuclear spin bath. Here
we report the measurement of the nuclear spin--lattice relaxation in a single
crystal of the single-molecule magnet Mn-ac, at mK in
perpendicular fields up to 9 T. Although the molecular spin is in
its ground state, we observe an increase of the nuclear relaxation rates by
several orders of magnitude up to the highest . This unique finding
is a consequence of the zero-point quantum fluctuations of the Mn-ac
spin, which allow it to efficiently transfer energy from the excited nuclear
spin bath to the lattice. Our experiment highlights the importance of quantum
fluctuations in the interaction between an `effective two-level system' and its
surrounding spin bath.Comment: 5 pages, 4 figure
EMDR Treatment in People with Mild ID and PTSD: 4 Cases
Although there is evidence to suggest that people with intellectual disabilities (ID) are likely to be more susceptible to the development of posttraumatic stress disorder (PTSD) than persons in the general population, until now only eight case reports on the treatment of people with ID suffering from PTSD symptoms have been published. In an effort to enrich the literature on this subject, the aim was to investigate the applicability of an evidence-based treatment for PTSD (i.e., EMDR) in four people with mild ID, suffering from PTSD following various kinds of trauma. In all cases PTSD symptoms decreased and the gains were maintained at 3 months to 2.5 year follow-up. In addition, depressive symptoms and physical complaints subsided, and social and adaptive skills improved. It is concluded that clientsâČ improvements converge to suggest the applicability of EMDR in people with mild ID. Difficulties involved in arriving at an accurate PTSD diagnosis in ID clients are discussed
Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath
Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin-lattice relaxation rate 1/T1n in a single crystal of the single-molecule magnet Mn12-ac, at Tâ30 mK in perpendicular fields Bâ„ up to 9 T. The relaxation channel at Bâ0 is dominated by incoherent quantum tunneling of the Mn12-ac spin S, aided by the nuclear bath itself. However for Bâ„>5 T we observe an increase of 1/T1n by several orders of magnitude up to the highest field, despite the fact that the molecular spin is in its quantum mechanical ground state. This striking observation is a consequence of the zero-point quantum fluctuations of S, which allow it to mediate the transfer of energy from the excited nuclear spin bath to the crystal lattice at much higher rates. Our experiment highlights the importance of quantum fluctuations in the interaction between an >effective two-level system> and its surrounding spin bath. © 2014 American Physical Society.This work has been part of the research program of the âStichting FOM.âPeer Reviewe
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