Abstract:
Decoherence is the process by which a quantum system interacts with its environment
and evolves into an arbitrary state, often irreversible nonunitary
evolution. This is a major setback for quantum information processing which
requires the preservation of coherence in the system for implementation of
quantum gates and also for storage of information (quantum memory). Dynamical
decoupling is a well known technique to prevent the decoherence of
open systems. We study the DD of multiqubit systems. Theory indicates
that local control on each qubit (DD pulses at different times on each qubit)
should perform better than global control (pulses at the same time). We observe
that this is not the case in a two qubit system. We then come up with
DD sequences based on the measured noise spectral density of the system
and study its performance as compared to standard DD sequences acting
locally and globally.
