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06/06/2014, 16:15 — 17:15 — Room P3.10, Mathematics Building

Hamed Mohammady, *Physics of Information Group - IT*

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Nuclear-electronic spin systems, magnetic resonance, and quantum
information processing

A promising platform for quantum information processing is that
of silicon impurities, where the quantum states are manipulated by
magnetic resonance. Such systems, in abstraction, can be considered
as a nucleus of arbitrary spin coupled to an electron of spin
one-half via an isotropic hype rfine interaction. We therefore
refer to them as "nuclear-electronic spin systems". The traditional
example, being subject to intensive experimental studies, is that
of phosphorus doped silicon (Si:P) which couples a spin one-half
electron to a nucleus of the same spin, with a hyperfine strength
of 117.5 MHz. More recently, bismuth doped silicon (Si:Bi) has been
suggested as an alternative instantiation of nuclear-electronic
spin systems, differing from Si:P by its larger nuclear spin and
hyperfine strength of 9/2 and 1.4754 GHz respectively. Here we
develop a model that is capable of predicting the magnetic
resonance properties of nuclear-electronic spin systems, which has
proven to be in good agreement with experiments. Furthermore, we
show that the larger nuclear spin and hyperfine strength of Si:Bi,
compared with that of Si:P, offer advantages for quantum
information processing by providing magnetic field-dependent
two-dimensional decoherence free subspaces, called optimal working
points or clock transitions, which have been identified to exist in
Si:Bi, but not Si:P.