Browsing by Author "Russo, Antonio"

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    General solution to inhomogeneous dephasing and smooth pulse dynamical decoupling
    Zeng, Junkai; Deng, Xiu-Hao; Russo, Antonio; Barnes, Edwin Fleming (Institute of Physics, 2018-03-26)
    In order to achieve the high-fidelity quantum control needed for a broad range of quantum information technologies, reducing the effects of noise and system inhomogeneities is an essential task. It is well known that a system can be decoupled from noise or made insensitive to inhomogeneous dephasing dynamically by using carefully designed pulse sequences based on square or delta-function waveforms such as Hahn spin echo or CPMG. However, such ideal pulses are often challenging to implement experimentally with high fidelity. Here, we uncover a new geometrical framework for visualizing all possible driving fields, which enables one to generate an unlimited number of smooth, experimentally feasible pulses that perform dynamical decoupling or dynamically corrected gates to arbitrarily high order.Wedemonstrate that this scheme can significantly enhance the fidelity of singlequbit operations in the presence of noise and when realistic limitations on pulse rise times and amplitudes are taken into account.
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    Generation of arbitrary all-photonic graph states from quantum emitters
    Russo, Antonio; Barnes, Edwin Fleming; Economou, Sophia E. (Institute of Physics, 2019-05-08)
    We present protocols to generate arbitrary photonic graph states from quantum emitters that are in principle deterministic.Wefocus primarily on two-dimensional cluster states of arbitrary size due to their importance for measurement-based quantum computing. Our protocols for these and many other types of two-dimensional graph states require a linear array of emitters in which each emitter can be controllably pumped, rotated about certain axes, and entangled with its nearest neighbors.We show that an error on one emitter produces a localized region of errors in the resulting graph state, where the size of the region is determined by the coordination number of the graph.Wedescribe how these protocols can be implemented for different types of emitters, including trapped ions, quantum dots, and nitrogen-vacancy centers in diamond.