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State and Measurement Tomography of an Exchange-Only Spin Qubit



Jacob M. Taylor, Medford Jim, Johannes Beil, Stephen Bartlett, Andrew Doherty, Emmanuel Rashba, David P. DiVincenzo, H Lu, A. C. Gossard


We demonstrate the initialization, full electrical control, and state tomography of an exchange- only spin qubit in a GaAs heterostructure. Decoherence and leakage from the qubit subspace are accounted for with a model of charge noise and fluctuating Overhauser fields. The linear triple quantum dot structure allows for the initialization of multiple high-fidelity input states, which are used with a Maximum Likelihood Estimation (MLE) technique to systematically characterize the generalized measurements in a demonstration of measurement tomography. This technique resulted in an average measurement fidelity of 75% and an average visibility of 49%.
Nature Nanotechnology


Quantum dots, quantum computing


Taylor, J. , Jim, M. , Beil, J. , Bartlett, S. , Doherty, A. , Rashba, E. , DiVincenzo, D. , Lu, H. and Gossard, A. (2013), State and Measurement Tomography of an Exchange-Only Spin Qubit, Nature Nanotechnology, [online], (Accessed June 25, 2024)


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Created September 1, 2013, Updated November 10, 2018