A research team at the University of Michigan in Ann Arbor and the University of Notre Dame in Indiana has reported the entanglement of three electrons in a CdTe quantum well using ultrafast laser pulses. The work, which was published in the March issue of Nature Materials, promises to enable the entanglement of larger numbers of particles for use in the development of a quantum computer.

To produce entangled electrons, the scientists generated localized excitons in the quantum well with 130-fs pulses from a mode-locked Ti:sapphire laser by tuning the laser to resonate with a gap 80 meV above the 1.6-eV bandgap of bulk CdTe. The excitons interact with electrons bound to noninteracting donors in the well, causing them to become spin-entangled in a process that establishes Raman coherences between the ground and optically excited states.