Quantum communication controlled by resonance in 'artificial atoms': "We capture the electrons in 'boxes'. Each box consist of a quantum dot, which is an artificial atom. The quantum dots are embedded in the semiconductor and each quantum dot can capture one electron. There needs to be three quantum dots next to each other using nanometer-scale electrostatic metal gates. When we open contact between the 'boxes' the electrons can sense each others' presence. The three spins must coordinate their orientations because it cost extra energy to put electrons with the same spin into the same box. To lower their energy, they not only spread out among the three boxes, but they orient their spins to further lower their energy. The three boxes together form a single entity – a qubit or quantum bit," explains Marcus.
An electrical signal is now sent from outside and by rapidly opening the boxes the system begins to swing in dynamic vibrations. The researchers can use this to change the quantum state of the electrons. "By combining three electrons in a triple quantum dot and oscillating an applied electric field at the frequency that separates adjacent energy levels, we can thus control the spins of the electrons without measuring them," explains Charles Marcus.