- document
-
Stilck França, Daniel (author), Markovich, L. (author), Dobrovitski, V.V. (author), Werner, Albert H. (author), Borregaard, J. (author)Characterizing the interactions and dynamics of quantum mechanical systems is an essential task in developing quantum technologies. We propose an efficient protocol based on the estimation of the time-derivatives of few qubit observables using polynomial interpolation for characterizing the underlying Hamiltonian dynamics and Markovian noise...journal article 2024
- document
-
Undseth, B.W. (author), Xue, X. (author), Mehmandoost, M. (author), Rimbach-Russ, Maximilian (author), Eendebak, P.T. (author), Samkharadze, Nodar (author), Sammak, A. (author), Dobrovitski, V.V. (author), Scappucci, G. (author), Vandersypen, L.M.K. (author)Micromagnet-based electric dipole spin resonance offers an attractive path for the near-term scaling of dense arrays of silicon spin qubits in gate-defined quantum dots while maintaining long coherence times and high control fidelities. However, accurately controlling dense arrays of qubits using a multiplexed drive will require an...journal article 2023
- document
-
Uysal, Mehmet T. (author), Raha, Mouktik (author), Chen, Songtao (author), Phenicie, Christopher M. (author), Ourari, Salim (author), Wang, Mengen (author), Van De Walle, Chris G. (author), Dobrovitski, V.V. (author), Thompson, Jeff D. (author)Individually addressed Er3+ ions in solid-state hosts are promising resources for quantum repeaters, because of their direct emission in the telecom band and their compatibility with silicon photonic devices. While the Er3+ electron spin provides a spin-photon interface, ancilla nuclear spins could enable multiqubit registers with longer...journal article 2023
- document
-
Dwyer, Bo L. (author), Rodgers, Lila V.H. (author), Urbach, Elana K. (author), Bluvstein, Dolev (author), Sangtawesin, Sorawis (author), Zhou, Hengyun (author), Nassab, Yahia (author), Fitzpatrick, Mattias (author), Dobrovitski, V.V. (author)Understanding the dynamics of a quantum bit's environment is essential for the realization of practical systems for quantum information processing and metrology. We use single nitrogen-vacancy (NV) centers in diamond to study the dynamics of a disordered spin ensemble at the diamond surface. Specifically, we reduce the density of "dark...journal article 2022
- document
-
Hahn, W. (author), Dobrovitski, V.V. (author)Long-lived coherences, emerging under periodic pulse driving in the disordered ensembles of strongly interacting spins, offer immense advantages for future quantum technologies, but the physical origin and the key properties of this phenomenon remain poorly understood. We theoretically investigate this effect in ensembles of different...journal article 2021
- document
-
Baier, S. (author), Bradley, C.E. (author), Middelburg, T. (author), Dobrovitski, V.V. (author), Taminiau, T.H. (author), Hanson, R. (author)The neutral charge state plays an important role in quantum information and sensing applications basedon nitrogen-vacancy centers. However, the orbital and spin dynamics remain unexplored. Here, we useresonant excitation of single centers to directly reveal the fine structure, enabling selective addressing ofspin-orbit states. Through pump-probe...journal article 2020
- document
-
Petit, L. (author), Boter, J.M. (author), Eenink, H.G.J. (author), Droulers, G. (author), Tagliaferri, M.L.V. (author), Li, R. (author), Franke, D.P. (author), Singh, K. J. (author), Clarke, J. S. (author), Schouten, R.N. (author), Dobrovitski, V.V. (author), Vandersypen, L.M.K. (author), Veldhorst, M. (author)We investigate the magnetic field and temperature dependence of the single-electron spin lifetime in silicon quantum dots and find a lifetime of 2.8 ms at a temperature of 1.1 K. We develop a model based on spin-valley mixing and find that Johnson noise and two-phonon processes limit relaxation at low and high temperature, respectively. We...journal article 2018
- document
-
Fotso, H. F. (author), Dobrovitski, V.V. (author)We investigate how the quantum control of a two-level system (TLS) coupled to photons can modify and tune the TLS's photon absorption spectrum. Tuning and controlling the emission and the absorption are of great interest, e.g., for the development of efficient interfaces between stationary and flying qubits in modern architectures for quantum...journal article 2017
- document
-
Mkhitaryan, V. V. (author), Dobrovitski, V.V. (author)We investigate the role of the nuclear-spin quantum dynamics in hyperfine-induced spin relaxation of hopping carriers in organic semiconductors. The fast-hopping regime, when the carrier spin does not rotate much between subsequent hops, is typical for organic semiconductors possessing long spin coherence times. We consider this regime and...journal article 2017
- document
-
Mkhitaryan, V. V. (author), Dobrovitski, V.V. (author)We present a theoretical analysis of the electron spin echo envelope modulation (ESEEM) spectra of polarons in semiconducting π-conjugated polymers. We show that the contact hyperfine coupling and the dipolar interaction between the polaron and the proton spins give rise to different features in the ESEEM spectra. Our theory enables direct...journal article 2017
- document
-
Kawakami, E. (author), Jullien, T.M.J. (author), Scarlino, P. (author), Ward, Daniel R. (author), Savage, Donald E. (author), Lagally, Max G. (author), Dobrovitski, V.V. (author), Friesen, Mark (author), Coppersmith, Susan N. (author), Eriksson, M.A. (author), Vandersypen, L.M.K. (author)The gate fidelity and the coherence time of a quantum bit (qubit) are important benchmarks for quantum computation. We construct a qubit using a single electron spin in an Si/SiGe quantum dot and control it electrically via an artificial spin-orbit field from a micromagnet. We measure an average single-qubit gate fidelity of ∼99% using...journal article 2016
- document
-
Bonato, C. (author), Blok, M.S. (author), Markham, M.L. (author), Twitchen, D.J. (author), Dobrovitski, V.V. (author), Hanson, R. (author)We report the control-free manipulation of a nuclear spin qubit in diamond, using only the backaction of sequential partial measurements with real-time feedback.conference paper 2014
- document
-
Blok, M.S. (author), Bonato, C. (author), Dobrovitski, V.V. (author), Hanson, R. (author)We present our most recent results on partial measurements of a nuclear spin in which the inevitable measurement back-action is controllably reduced. The post-selected measurement results can give rise to weak values. By using a real-time adaptive scheme the quantum state can be tuned using only measurements.conference paper 2013
- document
-
Taminiau, T.H. (author), Wagenaar, J.J.T. (author), Van der Sar, T. (author), Jelezko, F. (author), Dobrovitski, V.V. (author), Hanson, R. (author)We experimentally isolate, characterize, and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multipulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused...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
- document
-
Dobrovitski, V.V. (author), Feiguin, A.E. (author), Hanson, R. (author), Awschalom, D.D. (author)We study the Rabi oscillations decay of a spin decohered by a spin bath whose internal dynamics is caused by dipolar coupling between the bath spins. The form and rate of decay as a function of the intrabath coupling is obtained analytically, and confirmed numerically. The complex form of decay smoothly varies from power law to exponential, and...journal article 2009
- document
-
Fuchs, G.D. (author), Dobrovitski, V.V. (author), Hanson, R. (author), Batra, A. (author), Weis, C.D. (author), Schenkel, T. (author), Awschalom, D.D. (author)We use single-spin resonant spectroscopy to study the spin structure in the orbital excited state of a diamond nitrogen-vacancy (N-V) center at room temperature. The data show that the excited-state spin levels have a zero-field splitting that is approximately half of the value of the ground state levels, a g factor similar to the ground state...journal article 2008
- document
-
Dobrovitski, V.V. (author), Feiguin, A.E. (author), Awschalom, D.D. (author), Hanson, R. (author)We study decoherence of central spins by a spin bath, focusing on the difference between measurement of a single central spin and measurement of a large number of central spins (as found in typical spin-resonance experiments). For a dilute spin bath, the single spin demonstrates Gaussian free-induction decay, in contrast to exponential decay...journal article 2008