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Title: State-conditional coherent charge qubit oscillations in a Si/SiGe quadruple quantum dot

Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with high-fidelity single-qubit gates, strong efforts have been made in developing robust two-qubit logic gates in electrically gated quantum dot systems to realise a compact and nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations of a charge qubit. Using a quadruple quantum dot formed in a Si/SiGe heterostructure, we show the first demonstration of coherent two-axis control of a double quantum dot charge qubit in undoped Si/SiGe, performing Larmor and Ramsey oscillation measurements. We extract the strength of the capacitive coupling between a pair of double quantum dots by measuring the detuning energy shift (≈75 μeV) of one double dot depending on the excess charge configuration of the other double dot. Finally, we further demonstrate that the strong capacitive coupling allows fast, state-conditional Landau–Zener–Stückelberg oscillations with a conditional π phase flip time of about 80 ps, showing a promising pathway towards multi-qubit entanglement and control in semiconductor quantum dots.
 [1] ; ORCiD logo [2] ;  [3] ;  [3] ;  [4] ;  [4] ;  [4] ;  [4]
  1. Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  2. Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Seoul National Univ. (Korea, Republic of). Dept. of Physics and Astronomy
  3. Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering
  4. Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics
Publication Date:
Report Number(s):
Journal ID: ISSN 2056-6387; npjqi201632
Grant/Contract Number:
AC04-94AL85000; FG02-03ER46028; W911NF-12-0607; DMR-1206915; PHY-1104660; N00014-15-1-0029; 2E26681
Accepted Manuscript
Journal Name:
npj Quantum Information
Additional Journal Information:
Journal Volume: 2; Journal ID: ISSN 2056-6387
Nature Partner Journals
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org:
USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA); US Army Research Office (ARO); National Science Foundation (NSF); US Department of the Navy, Office of Naval Research (ONR); USDOD; Korea Inst. of Science and Technology (KIST) (Korea, Republic of); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
Seoul National Univ. (Korea, Republic of)
Country of Publication:
United States
97 MATHEMATICS AND COMPUTING; electronic and spintronic devices; quantum dots; quantum information; qubits; 77 NANOSCIENCE AND NANOTECHNOLOGY
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1356176