Dresden 2020 – scientific programme

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MA: Fachverband Magnetismus

MA 57: Posters Magnetism II

MA 57.38: Poster

Thursday, March 19, 2020, 15:00–18:00, P3

Decoherence of a singlet-triplet superposition state under dipolar interactions of an uncorrelated environment — •Patrick Vorndamme and Jürgen Schnack — Universität Bielefeld, PF 100131, D-33501 Bielefeld

By means of an STM it was shown recently that it is experimentally possible to stimulate clock transitions between the singlet and non-magnetic triplet state of a single Heisenberg coupled spin dimer. Large decoherence times of clock like states normally refer to ensembles of spins which do not dephase. Here we are interested in decoherence of one single dimer only. For this reason we simulate how a single entity of this dimers behaves in an environment of other spins which couple to the dimer via dipolar interactions. We perform unitary time evolutions in the complete Hilbert space, including dimer and a reasonably large environment. We find that for a weak environment this approach confirms long decoherence times for the clock like state, but with stronger couplings this statement does not hold. As a reference we compare the behavior of the dimer with other, non-clock like, superposition states. Furthermore, we show that the internal dynamics of the bath plays an important role for the decoherence time of the system. In a regime where the system is weakly coupled to the bath, stronger interactions between environmental spins worsen the decoherence time up to a certain degree while if system and bath are coupled strongly, stronger interactions in the environment improve decoherence times.