Another step forward on universal quantum computer
Yokohama National University
Yokohama, Japan - Researchers have demonstrated holonomic quantum gates under zero-magnetic field at room temperature, which will enable the realization of fast and fault-tolerant universal quantum computers. Researchers are currently working on the next step in quantum computing: building a universal quantum computer. The geometric phase gate or holonomic quantum gate has been experimentally demonstrated in several quantum systems including nitrogen-vacancy (NV) centers in diamond. To avoid unwanted interference, we used a degenerate subspace of the triplet spin qutrit to form an ideal logical qubit, which we call a geometric spin qubit, in an NV center. The scheme renders a purely holonomic gate without requiring an energy gap, which would have induced dynamic phase interference to degrade the gate fidelity, and thus enables precise and fast control over long-lived quantum memories, for realizing quantum repeaters interfacing between universal quantum computers and secure communication networks.