@article{discovery1410660, journal = {SCIENTIFIC REPORTS}, year = {2013}, volume = {3}, month = {November}, title = {Magnetically tunable singlet-triplet spin qubit in a four-electron InGaAs coupled quantum dot}, note = {{\copyright} 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}, issn = {2045-2322}, keywords = {Qubits; Quantum information}, url = {http://dx.doi.org/10.1038/srep03121}, abstract = {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.}, author = {Weiss, KM and Miguel-Sanchez, J and Elzerman, JM} }