How to build a 300 bit, 1 Giga-operation quantum computer

Experimental methods for laser control of trapped ions have reached sufficient maturity that it is possible to set out in detail a design for a large quantum computer based on such methods, without any major omissions or uncertainties. The main features of such a design are given, with a view to identifying areas for study. The machine is based on 13000 ions moved via 20m vacuum channels around a chip containing 160000 electrodes and associated classical control circuits; 1000 laser beam pairs are used to manipulate the hyperfine states of the ions and drive fluorescence for readout. The computer could run a quantum algorithm requiring 10⁹ logical operations on 300 logical qubits, with a physical gate rate of 1 MHz and a logical gate rate of 8 kHz, using methods for quantum gates that have already been experimentally implemented. Routes for faster operation are discussed.