Searched for: faculty%3A%22Applied%255C%252BSciences%22
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Schuetz, M.J.A. (author), Kessler, E.M. (author), Giedke, G. (author), Vandersypen, L.M.K. (author), Lukin, M.D. (author), Cirac, J.I. (author)
We propose a universal, on-chip quantum transducer based on surface acoustic waves in piezoactive materials. Because of the intrinsic piezoelectric (and/or magnetostrictive) properties of the material, our approach provides a universal platform capable of coherently linking a broad array of qubits, including quantum dots, trapped ions, nitrogen...
journal article 2015
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Scarlino, P. (author), Kawakami, E. (author), Ward, D.R. (author), Savage, D.E. (author), Lagally, M.G. (author), Friesen, M. (author), Coppersmith, S.N. (author), Eriksson, M.A. (author), Vandersypen, L.M.K. (author)
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...
journal article 2015
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Stano, P. (author), Klinovaja, J. (author), Braakman, F.R. (author), Vandersypen, L.M.K. (author), Loss, D. (author)
We investigate theoretically the long-distance coupling and spin exchange in an array of quantum dot spin qubits in the presence of microwaves. We find that photon-assisted cotunneling is boosted at resonances between photon and energies of virtually occupied excited states and show how to make it spin selective. We identify configurations that...
journal article 2015
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Scarlino, P. (author), Kawakami, E. (author), Stano, P. (author), Shafiei, M. (author), Reichl, C. (author), Wegscheider, W. (author), Vandersypen, L.M.K. (author)
We report that the electron spin-relaxation time T1 in a GaAs quantum dot with a spin-1/2 ground state has a 180° periodicity in the orientation of the in-plane magnetic field. This periodicity has been predicted for circular dots as being due to the interplay of Rashba and Dresselhaus spin orbit contributions. Different from this prediction, we...
journal article 2014
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Ferrari, A.C. (author), Dekker, C. (author), Vandersypen, L.M.K. (author), Van Der Zant, H.S.J. (author)
We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and...
journal article 2014
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Schuetz, M.J.A. (author), Kessler, E.M. (author), Vandersypen, L.M.K. (author), Cirac, J.I. (author), Giedke, G. (author)
We theoretically study the nuclear spin dynamics driven by electron transport and hyperfine interaction in an electrically defined double quantum dot in the Pauli-blockade regime. We derive a master-equation-based framework and show that the coupled electron-nuclear system displays an instability towards the buildup of large nuclear spin...
journal article 2014
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Braakman, F.R. (author), Danon, J. (author), Schreiber, L.R. (author), Wegscheider, W. (author), Vandersypen, L.M.K. (author)
We present time-resolved measurements of spin-flip photon-assisted tunneling and spin-flip relaxation in a doubly occupied double quantum dot. The photon-assisted excitation rate as a function of magnetic field indicates that spin-orbit coupling is the dominant mechanism behind the spin-flip under the present conditions. We are able to extract...
journal article 2014
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Calado, V.E. (author), Zhu, S.E. (author), Goswami, S. (author), Xu, Q. (author), Watanabe, K. (author), Taniguchi, T. (author), Janssen, G.C.A.M. (author), Vandersypen, L.M.K. (author)
In this letter, we report the observation of ballistic transport on micron length scales in graphene synthesised by chemical vapour deposition (CVD). Transport measurements were done on Hall bar geometries in a liquid He cryostat. Using non-local measurements, we show that electrons can be ballistically directed by a magnetic field (transverse...
journal article 2014
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Schuetz, M.J.A. (author), Kessler, E.M. (author), Vandersypen, L.M.K. (author), Cirac, J.I. (author), Giedke, G. (author)
We propose a scheme for the deterministic generation of steady-state entanglement between the two nuclear spin ensembles in an electrically defined double quantum dot. Because of quantum interference in the collective coupling to the electronic degrees of freedom, the nuclear system is actively driven into a two-mode squeezedlike target state....
journal article 2013
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Barthelemy, P.J.C. (author), Vandersypen, L.M.K. (author)
Quantum mechanics often results in extremely complex phenomena, especially when the quantum system under consideration is composed of many interacting particles. The states of these many-body systems live in a space so large that classical numerical calculations cannot compute them. Quantum simulations can be used to overcome this problem:...
journal article 2013
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Srinivasa, V. (author), Nowack, K.C. (author), Shafiei, M. (author), Vandersypen, L.M.K. (author), Taylor, J.M. (author)
We investigate phonon-induced spin and charge relaxation mediated by spin-orbit and hyperfine interactions for a single electron confined within a double quantum dot. A simple toy model incorporating both direct decay to the ground state of the double dot and indirect decay via an intermediate excited state yields an electron spin relaxation...
journal article 2013
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Braakman, F.R. (author), Barthelemy, P. (author), Reichl, C. (author), Wegscheider, W. (author), Vandersypen, L.M.K. (author)
We report both photon- and phonon-assisted tunneling transitions in a linear array of three quantum dots, which can only be understood by considering the full three-dimensionality of the charge stability diagram. Such tunneling transitions potentially contribute to leakage of qubits defined in this system. A detailed understanding of these...
journal article 2013
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Shafiei, M. (author), Nowack, K.C. (author), Reichl, C. (author), Wegscheider, W. (author), Vandersypen, L.M.K. (author)
We investigate the electric manipulation of a single-electron spin in a single gate-defined quantum dot. We observe that so-far neglected differences between the hyperfine- and spin-orbit-mediated electric dipole spin resonance conditions have important consequences at high magnetic fields. In experiments using adiabatic rapid passage to invert...
journal article 2013
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Barreiro, A. (author), Börrnert, F. (author), Avdoshenko, S.M. (author), Rellinghaus, B. (author), Cunibert, G. (author), Rümmeli, M.H. (author), Vandersypen, L.M.K. (author)
We shed light on the catalyst-free growth of graphene from amorphous carbon (a–C) by current induced annealing by witnessing the mechanism both with in-situ transmission electron microscopy and with molecular dynamics simulations. Both in experiment and in simulation, we observe that small a–C clusters on top of a graphene substrate rearrange...
journal article 2013
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Prance, J.R. (author), Shi, Z. (author), Siimins, C.B. (author), Savage, D.E. (author), Lagally, M.G. (author), Schreiber, L.R. (author), Vandersypen, L.M.K. (author), Friesen, M. (author), Joynt, R. (author), Coppersmith, S.N. (author), Eriksson, M.A. (author)
The spin singlet and triplet states of a two-electron double quantum dot can be used to form a logical qubit that combines fast manipulation and a spin readout mechanism. We demonstrate single-shot readout of the two-electron states of a Si/SiGe double quantum dot using a quantum-point-contact charge sensor and spin-to-charge conversion. From...
journal article 2012
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Prance, J.R. (author), Shi, Z. (author), Simmons, C.B. (author), Savage, D.E. (author), Lagally, M.G. (author), Schreiber, L.R. (author), Vandersypen, L.M.K. (author), Friesen, M. (author), Joynt, R. (author), Coppersmith, S.N. (author), Eriksson, M.A. (author)
conference paper 2012
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Calado, V.E. (author), Schneider, G.F. (author), Theulings, A.M.M.G. (author), Dekker, C. (author), Vandersypen, L.M.K. (author)
We study the formation of wrinkles in graphene upon wet transfer onto a hydrophilic target substrate, whereby draining of water appears to play an important role. We are able to control the orientation of the wrinkles by tuning the surface morphology. Wrinkles are absent in flakes transferred to strongly hydrophobic substrates, a further...
journal article 2012
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Goossens, A.M. (author), Calado, V.E. (author), Barreiro, A. (author), Watanabe, K. (author), Taniguchi, T. (author), Vandersypen, L.M.K. (author)
Contamination of graphene due to residues from nanofabrication often introduces background doping and reduces electron mobility. For samples of high electronic quality, post-lithography cleaning treatments are therefore needed. We report that mechanical cleaning based on contact mode atomic force microscopy removes residues and significantly...
journal article 2012
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Prance, J.R. (author), Shi, Z. (author), Simmons, C.B. (author), Savage, D.E. (author), Lagally, M.G. (author), Schreiber, L.R. (author), Vandersypen, L.M.K. (author), Friesen, M. (author), Joynt, R. (author), Coppersmith, S.N. (author), Eriksson, M.A. (author)
We investigate the lifetime of two-electron spin states in a few-electron Si/SiGe double dot. At the transition between the (1,1) and (0,2) charge occupations, Pauli spin blockade provides a readout mechanism for the spin state. We use the statistics of repeated single-shot measurements to extract the lifetimes of multiple states simultaneously....
journal article 2012
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Rudner, M.S. (author), Vandersypen, L.M.K. (author), Vuletic, V. (author), Levitov, L.S. (author)
We present a scheme for achieving coherent spin squeezing of nuclear spin states in semiconductor quantum dots. The nuclear polarization dependence of the electron spin resonance generates a unitary evolution that drives nuclear spins into a collective entangled state. The polarization dependence of the resonance generates an area-preserving,...
journal article 2011
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