title: Coherent two-electron spin qubits in an optically active pair of coupled InGaAs quantum dots.
abstract: In semiconductors, the T2* coherence time of a single confined spin is limited either by the fluctuating magnetic environment (via the hyperfine interaction), or by charge fluctuations (via the spin-orbit interaction). We demonstrate that both limitations can be overcome simultaneously by using two exchange-coupled electron spins that realize a single decoherence-avoiding qubit. Using coherent population trapping, we generate a coherent superposition of the singlet and triplet states of an optically active quantum dot molecule, and show that the corresponding T2* may exceed 200 ns.
authors.affiliation: Institute of Quantum Electronics, ETH Zurich, Zurich, Switzerland.
authors.forename: K M
authors.initials: KM
authors.lastname: Weiss
authors.forename: J M
authors.initials: JM
authors.lastname: Elzerman
authors.forename: Y L
authors.initials: YL
authors.lastname: Delley
authors.forename: J
authors.initials: J
authors.lastname: Miguel-Sanchez
authors.forename: A
authors.initials: A
authors.lastname: Imamoğlu