A monolithic array of three-dimensional ion traps fabricated with conventional semiconductor technology

The coherent control of quantum-entangled states of trapped ions(1) has led to significant advances in quantum information(2), quantum simulation(3), quantum metrology(4,5) and laboratory tests of quantum mechanics(6) and relativity(7). All of the basic requirements for processing quantum information with arrays of ion-based quantum bits (qubits) have been proven in principle(8). However, so far, no more than 14 ion-based qubits have been entangled with the ion-trap approach(9), so there is a clear need for arrays of ion traps that can handle a much larger number of qubits(10). Traps consisting of a two-dimensional electrode array(11) have undergone significant development, but three-dimensional trap geometries can create a superior confining potential. However, existing three-dimensional approaches, as used in the most advanced experiments with trap arrays(8,12), cannot be scaled up to handle greatly increased numbers of ions. Here, we report a monolithic three-dimensional ion microtrap array etched from a silica-on-silicon wafer using conventional semiconductor fabrication technology. We have confined individual Sr-88(+) ions and strings of up to 14 ions in a single segment of the array. We have measured motional frequencies, ion heating rates and storage times. Our results demonstrate that it should be possible to handle several tens of ion-based qubits with this approach.