Psychiatric and psychosocial outcome of orthotopic liver transplantation

Background. The study aimed to explore the prevalence of psychiatric disorders among orthotopic liver transplantation (OLT) recipients, and to investigate how psychiatric morbidity was linked to health-related quality of life (HRQOL). Methods: We recruited 75 patients who had undergone OLT a median of 3.8 years previously (range = 5-129 months). Psychiatric morbidity was assessed using the Structural Clinical Interview for the IDSM-III-R. Psychometric observer-rating and self-rating scales were administered to evaluate cognitive functioning (SKT), depressive symptomatology (HAMD(17)), Posttraumatic stress symptoms (PTSS-10), social support (SSS), and HRQOL (SF-36 Health Status Questionnaire). Treatment characteristics were obtained from medical records. Results: 22.7% (n = 17) of our sample had a current or probable psychiatric diagnosis according to DSM-III-R: 2.7% full posttraumatic stress disorder (PTSD) (n = 2), 2.7% major depressive disorder (MDD) comorbid to full PTSD (n = 2), 1.3% MDD comorbid to partial PTSD (n = 1), and 16% partial PTSD (n = 12). Patients with PTSD symptoms demonstrated lower cognitive performance, higher severity of depressive symptoms and more unfavorable perception of social support. OLT-related PTSD symptomatology was associated with maximal decrements in HRQOL. The duration of intensive care treatment, the number of medical complications, and the occurrence of acute rejection were positively correlated with the risk of PTSD symptoms subsequent to OLT. Conclusion: OLT-related PTSD symptomatology impairing HRQOL is a complication for a subgroup of OLT recipients. Health-care providers should be aware of the possible presence of PTSD in OLT survivors. Copyright (C) 2002 S. KargerAG, Basel

Decoding the Projective Transverse Field Ising Model

The competition between non-commuting projective measurements in discrete quantum circuits can give rise to entanglement transitions. It separates a regime where initially stored quantum information survives the time evolution from a regime where the measurements destroy the quantum information. Here we study one such system - the projective transverse field Ising model - with a focus on its capabilities as a quantum error correction code. The idea is to interpret one type of measurement as an error and the other type as a syndrome measurement. We demonstrate that there is a finite threshold below which quantum information encoded in an initially entangled state can be retrieved reliably. In particular, we implement the maximum likelihood decoder to demonstrate that the error correction threshold is distinct from the entanglement transition. This implies that there is a finite regime where quantum information is protected by the projective dynamics, but cannot be retrieved by using syndrome measurements.Comment: 18 pages, 9 figure

Functional completeness of planar Rydberg blockade structures

The construction of Hilbert spaces that are characterized by local constraints as the low-energy sectors of microscopic models is an important step towards the realization of a wide range of quantum phases with long-range entanglement and emergent gauge fields. Here we show that planar structures of trapped atoms in the Rydberg blockade regime are functionally complete: Their ground state manifold can realize any Hilbert space that can be characterized by local constraints in the product basis. We introduce a versatile framework, together with a set of provably minimal logic primitives as building blocks, to implement these constraints. As examples, we present lattice realizations of the string-net Hilbert spaces that underlie the surface code and the Fibonacci anyon model. We discuss possible optimizations of planar Rydberg structures to increase their geometrical robustness.Comment: 33 pages, 14 figures, v2: fixed typos, added additional references and comment

Minimal instances for toric code ground states

A decade ago Kitaev's toric code model established the new paradigm of topological quantum computation. Due to remarkable theoretical and experimental progress, the quantum simulation of such complex many-body systems is now within the realms of possibility. Here we consider the question, to which extent the ground states of small toric code systems differ from LU-equivalent graph states. We argue that simplistic (though experimentally attractive) setups obliterate the differences between the toric code and equivalent graph states; hence we search for the smallest setups on the square- and triangular lattice, such that the quasi-locality of the toric code hamiltonian becomes a distinctive feature. To this end, a purely geometric procedure to transform a given toric code setup into an LC-equivalent graph state is derived. In combination with an algorithmic computation of LC-equivalent graph states, we find the smallest non-trivial setup on the square lattice to contain 5 plaquettes and 16 qubits; on the triangular lattice the number of plaquettes and qubits is reduced to 4 and 9, respectively.Comment: 14 pages, 11 figure