Study suggests trapped ions could share GKP qubits over long distances

[Cole99]

Researchers from Keio University and NICT in Japan have analysed how to create entanglement between special error correcting qubits held in distant trapped ions. Quantum Zeitgeist's Ivy Delaney reports that their scheme could achieve fidelities above 95 percent. It would be a useful step towards modular quantum computers and networks

The qubits in question are Gottesman Kitaev Preskill states, usually called GKP qubits. They encode quantum information in the motion of a trapped ion, in a way that has error correction built in. Linking them across separate machines has been a long standing challenge

The study is a numerical analysis rather than an experiment. With 6 decibels of squeezing, the predicted fidelity is 91.78 percent. With 15 decibels, it rises to 98.82 percent. That shows how much depends on the quality of the GKP states themselves

Remote entanglement is essential for connecting quantum processors together. A single machine can only hold so many qubits, so linking several modules is one of the most promising ways to scale. Doing it with error correcting qubits from the start could save a lot of overhead later

It is encouraging work, though experiments will be the real test. Trapped ion groups have already made GKP states in the lab, so the building blocks exist. Combining them with remote links is the next big challenge

Is modular quantum computing the best way to scale? And how close are experiments to this level of squeezing?

Researchers Generate Remote Entanglement At 95% Fidelityquantumzeitgeist.com