Backaction due to Resonant Phonon Absorption in Quantum Dots Measured by a Quantum Point Contact

Recent experiments have observed unexplained periodic resonances in the charging diagrams of both double [1] and triple [2] quantum dots (DQDs and TQDs). These resonances correspond to the generation of inelastic transitions, driven by energy transfer from a biased quantum point contact (QPC) charge detector used for measurement. In this talk, we present theoretical results describing how quantum backaction due to hot phonons, generated by the out-of-equilibrium QPC, can lead to excited state occupation under certain ``blocking'' conditions that result in slow ground state filling. We propose that recent experiments can be understood in terms of resonant phonon absorption in DQDs and TQDs; a process complementary to resonant phonon emission [3]. Our results shed light on an important contribution to the backaction of the QPC readout scheme widely used for QD-based quantum computation. \\[4pt] [1] D. Harbusch et al., Phys. Rev. Lett., 104, 196801 (2010). \\[0pt] [2] L. Gaudreau et al., App. Phys. Lett., 99, 193101 (2009). \\[0pt] [3] U. Gasser et al., Phys. Rev. B, 79, 035303 (2009).