title: Second-Harmonic Coherent Driving of a Spin Qubit in a Si/SiGe Quantum Dot.
abstract: We demonstrate coherent driving of a single electron spin using second-harmonic excitation in a Si/SiGe quantum dot. Our estimates suggest that the anharmonic dot confining potential combined with a gradient in the transverse magnetic field dominates the second-harmonic response. As expected, the Rabi frequency depends quadratically on the driving amplitude, and the periodicity with respect to the phase of the drive is twice that of the fundamental harmonic. The maximum Rabi frequency observed for the second harmonic is just a factor of 2 lower than that achieved for the first harmonic when driving at the same power. Combined with the lower demands on microwave circuitry when operating at half the qubit frequency, these observations indicate that second-harmonic driving can be a useful technique for future quantum computation architectures.
authors.affiliation: Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Scarlino
authors.affiliation: Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: Kawakami
authors.affiliation: University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: D R
authors.initials: DR
authors.lastname: Ward
authors.affiliation: University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: D E
authors.initials: DE
authors.lastname: Savage
authors.affiliation: University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Lagally
authors.affiliation: University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Friesen
authors.affiliation: University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: S N
authors.initials: SN
authors.lastname: Coppersmith
authors.affiliation: University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Eriksson
authors.affiliation: Kavli Institute of Nanoscience, TU Delft, Lorentzweg 1, 2628 CJ Delft, Netherlands.
authors.forename: L M K
authors.initials: LM
authors.lastname: Vandersypen