arXiv subjects

Thomas Brabec

Publications and source records attributed to Thomas Brabec.

22 records · Page 2Linked to original sources

arXiv2011

Spin-blockade effect and coherent control of DNA-damage by free radicals: a proposal on bio-spintronics

Coherent control of OH-free radicals interacting with the spin-triplet state of a DNA molecule is investigated. A model Hamiltonian for molecular spin singlet-triplet resonance is developed. We illustrate that the spin-triplet state in DNA molecules can be efficiently populated, as the spin-injection rate can be tuned to be orders of magnitudes greater than the decay rate due to small spin-orbit coupling in organic molecules. Owing to the nano-second life-time of OH free radicals, a non-equilibrium free energy barrier induced by the injected spin triplet state that lasts approximately longer than one-micro second in room temperature can efficiently block the initial Hydrogen abstraction and DNA damage. For a direct demonstration of the spin-blockade effect, a molecular simulation based on an {\em ab-initio} Car-Parrinello molecular dynamics is deployed.

physics.chem-ph↗

arXiv2011

Reactive Molecular Dynamics study on the first steps of DNA-damage by free hydroxyl radicals

We employ a large scale molecular simulation based on bond-order ReaxFF to simulate the chemical reaction and study the damage to a large fragment of DNA-molecule in the solution by ionizing radiation. We illustrate that the randomly distributed clusters of diatomic OH-radicals that are primary products of megavoltage ionizing radiation in water-based systems are the main source of hydrogen-abstraction as well as formation of carbonyl- and hydroxyl-groups in the sugar-moiety that create holes in the sugar-rings. These holes grow up slowly between DNA-bases and DNA-backbone and the damage collectively propagate to DNA single and double strand break.

physics.bio-ph↗

arXiv2010

Performance engineering of semiconductor spin qubit systems

The performance of a quantum computation system is investigated, with qubits represented by magnetic impurities in coupled quantum dots filled with two electrons. Magnetic impurities are electrically manipulated by electrons. The dominant noise source is the electron mediated indirect coupling between magnetic impurities and host spin bath. As a result of the electron mediated coupling, both noise properties and the time needed for elementary gate operations, depend on controllable system parameters, such as size and geometry of the quantum dot, and external electric and magnetic fields. We find that the maximum number of quantum operations per coherence time for magnetic impurities increases as electron spin singlet triplet energy gap decreases. The advantage of magnetic impurities over electrons for weak coupling and large magnetic fields will be illustrated.

cond-mat.mes-hall↗

arXiv2005

Transport properties of nano-devices: One-dimensional model study

A 1D model study of charge transport in nano-devices is made by comparing multi-configuration time dependent Hartree-Fock and frozen core calculations. The influence of exchange and Coulomb correlation on the tunneling current is determined. We identify the shape of the tunneling barrier and the resonance structure of the nano-device as the two dominant parameters determining the electron transport. Whereas the barrier shape determines the size of the tunneling current, the resonances determine the structure of the current.

cond-mat.mes-hall↗