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Valley-based noise-resistant quantum computation using Si quantum dots

André Saraiva (UFRJ)

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We devise a platform for noise-resistant quantum computing using the  valley degree of freedom of Si quantum dots [1]. The qubit is encoded  in two polarized (1,1) spin-triplet states with different valley compositions in a double quantum dot, with a Zeeman field enabling unambiguous initialization. A top  
gate gives a difference in the valley splitting between the dots, allowing controllable interdot tunneling between opposite valley eigenstates [2,3], which enables one-qubit rotations. Two-qubit operations rely on a stripline resonator, and readout on charge sensing. Sensitivity to charge and spin fluctuations is determined by intervalley processes and is greatly reduced as compared to conventional spin and charge qubits. We describe a valley echo for further noise suppression.

[1] Dimitrie Culcer, A. L. Saraiva, Belita Koiller, Xuedong Hu, and S. Das Sarma, Phys. Rev. Lett. 108, 126804 (2012)

[2] A. L. Saraiva, M. J. Calderón, Xuedong Hu, S. Das Sarma, and Belita Koiller, Phys. Rev. B 80, 081305 (2009)

[3] A. L. Saraiva, M. J. Calderón, Rodrigo B. Capaz, Xuedong Hu, S. Das Sarma, and Belita Koiller, Phys. Rev. B 84, 155320 (2011)