TY - JOUR TI - Magnetically tunable singlet-triplet spin qubit in a four-electron InGaAs coupled quantum dot Y1 - 2013/11/01/ SN - 2045-2322 AV - public N2 - A pair of self-assembled InGaAs quantum dots filled with two electrons can act as a singlet-triplet spin qubit that is robust against nuclear spin fluctuations as well as charge noise. This results in a T2* coherence time two orders of magnitude longer than that of a single electron, provided the qubit is operated at a particular ??sweet spot?? in gate voltage. However, at this fixed operating point the ground-state splitting can no longer be tuned into resonance with e.g. another qubit, limiting the options for coupling multiple qubits. Here, we propose using a four-electron coupled quantum dot to implement a singlet-triplet qubit that features a magnetically tunable level splitting. As a first step towards full experimental realization of this qubit design, we use optical spectroscopy to demonstrate the tunability of the four-electron singlet-triplet splitting in a moderate magnetic field. ID - discovery1410660 UR - http://dx.doi.org/10.1038/srep03121 N1 - © 2013 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 3.0 Unported license. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0 PubMed ID: 24177037 VL - 3 KW - Qubits; Quantum information A1 - Weiss, KM A1 - Miguel-Sanchez, J A1 - Elzerman, JM JF - SCIENTIFIC REPORTS ER -