Lecturer: Ramil Nigmatullin
Abstract:
Optically linked ion traps are promising as components of network-based quantum technologies, including communication systems and modular computers. Experimental results achieved to date indicate that the fidelity of operations within each ion trap module will be far higher than the fidelity of operations involving the links; fortunately internal storage and processing can effectively upgrade the links through the process of purification. This talk will present a detailed analysis on this purification task, using a protocol which is balanced to maximize fidelity while minimizing the device complexity and the time cost of the process. The derived quantum circuit is 'compiled down' to device-level operations including cooling and shuttling events. It is found that a linear trap with only five ions (two of one species, three of another) can support our protocol while incorporating desirable features such as global control, i.e. laser control pulses need only target an entire zone rather than differentiating one ion from its neighbor. The capabilities of such module are evaluated by considering its use as a universal communications node for quantum key distribution and as the basis of the repeating unit of a quantum computer. For the latter case, the threshold for fault tolerant quantum computing is evaluated using the surface code, finding acceptable fidelities for the 'raw' entangling link as low as 83%.