L17.00008. Full Permutation Dynamical Decoupling in an Encoded Triple-Dot Qubit

Presented by: Bo Sun


Dynamical decoupling (DD) sequences can mitigate decoherence induced by slowly varying interactions between a qubit and a bath by using appropriately timed qubit rotations. For an exchange only qubit encoded in the spins of three electrons, dynamical decoupling can be achieved by applying a series of full-SWAP operations on the constituent spins which fully permute their locations across the three dots [1]. Using gate-defined quantum dots in an enriched Si/SiGe device, we demonstrate that repeated applications of the full permutation sequence can echo low frequency charge and magnetic noise, resulting a dynamically decoupled coherence time of 100s of microseconds. We find that the first order DD sequence is susceptible to rotations about the Y-axis of the Bloch sphere, driven by either real magnetic field gradients or spin-orbit pseudo-gradients. Initializing the qubit along the Y axis renders the experiment insensitive to these errors, as implied by measurements of qubit leakage in this configuration. The resulting experiment is only sensitive to high-frequency noise sources and is similar to noise spectroscopy. We compare our results to simulations which include various types of high-frequency charge noise. 1. J R West and B H Fong New J. Phys. 14 083002 (2012)


  • Bo Sun


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