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Relaxation times do not capture logical qubit dynamics
, Philipp Schindler, Alexander Erhard, {\'{A}}ngel Rivas, Miguel-Angel Martin-Delgado, Rainer Blatt, Thomas Monz, Markus M{\"{u}}ller
Published in Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften
2020
Volume: 7911
   
Abstract
Quantum error correction procedures have the potential to enable faithful operation of large-scale quantum computers. They protect information from environmental decoherence by storing it in logical qubits, built from ensembles of entangled physical qubits according to suitably tailored quantum error correcting encodings. To date, no generally accepted framework to characterise the behaviour of logical qubits as quantum memories has been developed. In this work, we show that generalisations of well-established figures of merit of physical qubits, such as relaxation times, to logical qubits fail and do not capture dynamics of logical qubits. We experimentally illustrate that, in particular, spatial noise correlations can give rise to rich and counter-intuitive dynamical behavior of logical qubits. We show that a suitable set of observables, formed by code space population and logical operators within the code space, allows one to track and characterize the dynamical behaviour of logical qubits. Awareness of these effects and the efficient characterisation tools used in this work will help to guide and benchmark experimental implementations of logical qubits.
About the journal
JournalarXiv preprint arXiv:2012.
PublisherVerein zur Forderung des Open Access Publizierens in den Quantenwissenschaften
ISSN2521327X
Open AccessNo