Searched for: author:"Riste, D."
(1 - 9 of 9)
document
Ristè, D. (author)
Superconducting circuits have recently risen to the forefront of the solid-state prototypes for quantum computing. Reaching the stage of robust quantum computing requires closing the loop between measurement and control of quantum bits (qubits). This thesis presents the realization of feedback control of superconducting qubits based on...
doctoral thesis 2014
document
De Lange, G. (author), Riste, D. (author), Tiggelman, M.J. (author), Eichler, C. (author), Tornberg, L. (author), Johansson, G. (author), Wallraff, A. (author), Schouten, R.N. (author), DiCarlo, L. (author)
We demonstrate the active suppression of transmon qubit dephasing induced by dispersive measurement, using parametric amplification and analog feedback. By real-time processing of the homodyne record, the feedback controller reverts the stochastic quantum phase kick imparted by the measurement on the qubit. The feedback operation matches a model...
journal article 2014
document
Groen, J.P. (author), Riste, D. (author), Tornberg, L. (author), Cramer, J. (author), De Groot, P.C. (author), Picot, T. (author), Johansson, G. (author), DiCarlo, L. (author)
We realize indirect partial measurement of a transmon qubit in circuit quantum electrodynamics by interaction with an ancilla qubit and projective ancilla measurement with a dedicated readout resonator. Accurate control of the interaction and ancilla measurement basis allows tailoring the measurement strength and operator. The tradeoff between...
journal article 2013
document
Riste, D. (author), Bultink, C.C. (author), Tiggelman, M.J. (author), Schouten, R.N. (author), Lehnert, K.W. (author), DiCarlo, L. (author)
The tunnelling of quasiparticles across Josephson junctions in superconducting quantum circuits is an intrinsic decoherence mechanism for qubit degrees of freedom. Understanding the limits imposed by quasiparticle tunnelling on qubit relaxation and dephasing is of theoretical and experimental interest, particularly as improved understanding of...
journal article 2013
document
Riste, D. (author), Bultink, C.C. (author), Lehnert, K.W. (author), DiCarlo, L. (author)
We demonstrate feedback control of a superconducting transmon qubit using discrete, projective measurement and conditional coherent driving. Feedback realizes a fast and deterministic qubit reset to a target state with 2.4% error averaged over input superposition states, and allows concatenating experiments more than 10 times faster than by...
journal article 2012
document
Riste, D. (author), Van Leeuwen, J.G. (author), Ku, H.S. (author), Lehnert, K.W. (author), DiCarlo, L. (author)
We demonstrate initialization by joint measurement of two transmon qubits in 3D circuit quantum electrodynamics. Homodyne detection of cavity transmission is enhanced by Josephson parametric amplification to discriminate the two-qubit ground state from single-qubit excitations nondestructively and with 98.1% fidelity. Measurement and...
journal article 2012
document
Wang, Z.H. (author), De Lange, G. (author), Riste, D. (author), Hanson, R. (author), Dobrovitski, V.V. (author)
We perform a detailed theoretical-experimental study of the dynamical decoupling (DD) of the nitrogen-vacancy (NV) center in diamond. We investigate the DD sequences applied to suppress the dephasing of the electron spin of the NV center induced by the coupling to a spin bath composed of the substitutional nitrogen atoms. The decoupling...
journal article 2012
document
De Lange, G. (author), Ristè, D. (author), Dobrovitski, V.V. (author), Hanson, R. (author)
We experimentally demonstrate single-spin magnetometry with multipulse sensing sequences. The use of multipulse sequences can greatly increase the sensing time per measurement shot, resulting in enhanced ac magnetic field sensitivity. We theoretically derive and experimentally verify the optimal number of sensing cycles, for which the effects of...
journal article 2011
document
Dobrovitski, V.V. (author), De Lange, G. (author), Ristè, D. (author), Hanson, R. (author)
Long-time dynamical decoupling and quantum control of qubits require high-precision control pulses. Full characterization (quantum tomography) of imperfect pulses presents a bootstrap problem: tomography requires initial states of a qubit which cannot be prepared without perfect pulses. We present a protocol for pulse error analysis,...
journal article 2010
Searched for: author:"Riste, D."
(1 - 9 of 9)