Exquisite quantum control has now been achieved in small ion traps, in
nitrogen-vacancy centres and in superconducting qubit clusters. We can regard
such a system as a universal cell with diverse technological uses from
communication to large-scale computing, provided that the cell is able to
network with others and overcome any noise in the interlinks. Here we show that
loss-tolerant entanglement purification makes quantum computing feasible with
the noisy and lossy links that are realistic today: With a modestly complex
cell design, and using a surface code protocol with a network noise threshold
of 13.3%, we find that interlinks which attempt entanglement at a rate of 2MHz
but suffer 98% photon loss can result in kilohertz computer clock speeds (i.e.
rate of high fidelity stabilizer measurements). Improved links would
dramatically increase the clock speed. Our simulations employed local gates of
a fidelity already achieved in ion trap devices.Comment: corrected typos, additional references, additional figur