Universal quantum computers are still far from being practical at the moment, but with each passing day and each new invention, we are inching ahead towards tht ultimate goal.
A huge step in this direction was taken and demonstrated by a team of scientists through their study in journal Nature Communications wherein they showed off holonomic quantum gates under zero-magnetic field at room temperature, which will enable the realization of fast and fault-tolerant universal quantum computers. A quantum computer is a powerful machine with the potential to solve complex problems much faster than today’s conventional computer can. Researchers are currently working on the next step in quantum computing: building a universal quantum computer.
Researchers report in the paper an experimental demonstration of non-adiabatic and non-abelian holonomic quantum gates over a geometric spin qubit on an electron or nitrogen nucleus, which paves the way to realizing a universal quantum computer. The geometric phase is currently a key issue in quantum physics. A holonomic quantum gate manipulating purely the geometric phase in the degenerate ground state system is believed to be an ideal way to build a fault-tolerant 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. However, previous experiments required microwaves or light waves to manipulate the non-degenerate subspace, leading to the degradation of gate fidelity due to unwanted interference of the dynamic phase.
The group also demonstrated a two-qubit holonomic gate to show universality by manipulating the electron-nucleus entanglement. 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.