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Oral: Andrew Sachrajda
Three Spin Coherent Interference Behavior
Co-authors: Gabriel Poulin-Lamarre, Joelle Thorgrimson, Sergei Studenikin, Geof Aers, Alicia Kam, Piotr Zawadzki, Zbig Wasilewski
Invited: Dohun Kim
Quantum Control & Process Tomography of a Semiconductor Quantum Dot Hybrid Qubit
Co-authors: Zhan Shi, C. B. Simmons, D. R. Ward, Jon Prance, Teck Seng Koh, John King Gamble, Don E. Savage, M. G. Lagally, Mark Friesen, Susan N. Coppersmith, Mark A. Eriksson
We experimentally demonstrate quantum operations and tomographic characterization of a quantum dot hybrid qubit: a qubit based on three electrons in two dots formed in a Si/SiGe heterostructure that was proposed theoretically in . Full qubit control on the Bloch sphere is performed using fast changes to only a single gate voltage used as the qubit control parameter . X rotations are performed at the anticrossing between the (1,2) and (2,1) charge-like ground states, while Z rotations are performed through the use of phase accumulation between the ground state and an excited state with the same charge occupation. We measure a rotation rate of ~5 GHz (~11GHz) and a T2* of ~2ns (~10ns) for X (Z) rotations, both of which have visibility greater than 80%. Tomographic characterization of the hybrid qubit is performed through state and process tomography; measurements are performed in the Pauli basis and analyzed using maximum likelihood estimation. We show that the process fidelities for the X(π) and Z(π) gate operations are higher than 84% and 94%, respectively, demonstrating a promising combination of high speed, high fidelity, and efficient control in a semiconductor quantum dot qubit .