Quantum control of a high-speed semiconductor quantum dot hybrid qubit
Mark A. Eriksson
Department of Physics, University of Wisconsin-Madison
One of the remarkable features of qubits formed by spins in the solid state is the enormous range of time-scales over which coherent manipulation is possible. If one considers gate-controlled manipulation of nuclear spins at one extreme , and exchange-driven multi-electron qubits at the other extreme [2,3], coherent control of semiconductor qubits with over 9 orders of magnitude variation in manipulation time has already been demonstrated. In this talk, I present recent work on the high-speed end of this spectrum using quantum dots in Si/SiGe heterostructures . I will discuss a three-electron, double quantum dot-based qubit and demonstrate its control by means of abrupt (~100 ps) changes in the detuning energy between the quantum dots. I will also discuss recent experiments using microwave pulses to operate this qubit entirely in regimes that are well-protected from charge noise, yielding much improved coherence . In this regime, it is possible to tune the internal degrees of freedom of this qubit, further increasing qubit coherence while maintaining qubit operational speed. This capability implies that careful hardware design may be able to improve the properties of quantum dot qubits.
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