We present measurements of resonant tunneling through discrete energy levels of a silicon double quantum dot formed in a thin silicon-on-insulator layer. In the absence of piezoelectric phonon coupling, spontaneous phonon emission with deformation-potential coupling accounts for inelastic tunneling through the ground states of the two dots. Such transport measurements enable us to observe a Pauli spin blockade due to effective two-electron spin-triplet correlations, evident in a distinct bias-polarity dependence of resonant tunneling through the ground states. The blockade is lifted by the excited-state resonance by virtue of efficient phonon emission between the ground states. Our experiment demonstrates considerable potential for investigating silicon-based spin dynamics and spin-based quantum information processing.

We report on nonadiabatic transport through a double quantum dot under irradiation of surface acoustic waves generated on chip. At low excitation powers, absorption and emission of single and multiple phonons are observed. At higher power, sequential phonon assisted tunneling processes excite the double dot in a highly nonequilibrium state. The present system is attractive for studying electron-phonon interaction with piezoelectric coupling. DOI: 10.1103/PhysRevLett.96.136807 PACS numbers: 73.23.Hk, 63.20.Kr, 77.65.Dq Electron-phonon coupling often leads to dissipation and decoherence problems in nanoelectronic devices. The decoherence in a tunable two-level quantum system (qubit), such as a double quantum dot (DQD) [1], is of particular interest in the recent light of quantum computation and information [2]. It was found that piezoelectric coupling to acoustic phonons is the dominant mechanism for inelastic transition between two charge states in a DQD [3], as confirmed by theory [4]. In analogy to quantum states in natural atoms-which dominantly couple to and are successfully controlled by photons-the electronic states in solid state systems may be controlled by phonons, taking advantage of the strong electron-phonon coupling.Because of the piezoelectric coupling in GaAs, surface acoustic waves (SAWs) can be generated by applying a microwave signal to an interdigital transducer (IDT) [5]. The accompanying propagating and oscillating potential has been used in several experiments to transport photogenerated electrons and holes in so-called ''dynamical quantum dots '' [6]. In those experiments, however, the SAWs give rise to an adiabatic change of the electronic states, where the carriers remain in an eigenstate of the temporal potential.In this Letter, we present nonadiabatic transitions in a lithographically defined DQD under irradiation of coherent SAWs. We observe resonant phonon assisted tunneling, where transport is well described by considering absorption and emission of one or multiple phonons during the tunneling process [7]. The present results unambiguously indicate a finite contribution of SAWs to the bosonic environment of a quantum two-level system formed by a DQD. Moreover, these transport measurements allow us to determine extremely small amplitudes of the local piezoelectric potential.

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