Regensburg 2022 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
QI: Fachverband Quanteninformation
QI 1: Implementations: Spin Qubits, Atoms, and Photons
QI 1.6: Vortrag
Montag, 5. September 2022, 11:15–11:30, H8
Coherence improvements at a higher-order sweet spot in double quantum dots — •Morten I. K. Munk1,2, Martin Leijnse1, and Peter Samuelsson2 — 1NanoLund and Division of Solid State Physics, Lund University, Lund, Sweden — 2NanoLund and Division of Mathematical Physics, Lund University, Lund, Sweden
One of the main limiting factors for designing a useful qubit is its dephasing time. In order to improve this, qubits are often operated at optimal points, or so-called "sweet spots", but in recent years, several systems have been proposed which can be tuned to higher-order sweet spots. These qubits often fail in practice, due for example to coupling to leakage states or a lack of protection against other relevant noise sources. In this work we propose a straightforward way of achieving a third-order sweet spot in a double quantum dot with two electrons in the singlet sector. This experimentally feasible qubit has the combined advantages of being operated at strong tunneling strengths, where leakage states are well separated from the qubit states, as well as being possible to construct in a way in which there are no relevant unprotected noise channels. We investigate the decoherence rate due to pure dephasing for a broad range of system parameters and for different noise spectral densities. It is found, in general, that higher-order sweet spots allow for substantially increased dephasing times, suggesting a guiding principle in optimizing the coherence properties of charge qubits in double quantum dots and related systems.