A team of researchers working at the University of Oxford has found that quantum bits (qubits) based on trapped calcium ions can be both manipulated and fashioned to store qubits with higher fidelity than any other method seen thus far. In their paper published in Physical Review Letters, the team describes how they built a means for testing the feasibility of using Ca+ ions as the basis for quantum computing and what they found in doing so.
Qubits made of a trapped 43Ca+ ion. RF and dc electrodes provide a trapping field for the ions, which are cooled by laser beams (blue) to microkelvin temperatures. A combination of laser pumping and microwave signals can deterministically prepare the qubit in a |0〉 or |1〉 state, and the state can be read out by monitoring its fluorescence (only |1〉 states result in the fluorescence, similar to that shown in the inset). Further logical gate operations can be carried out by applying various combinations of microwave pulses. The scheme yields preparation and readout errors of less than 0.07% and logic-gate errors of less than 10-6. Credit: APS/Alan Stonebraker
Scientists around the world are hard at work trying to figure out how to build a functional, useful quantum computer—while much progress has been made there are still areas that are problematic, one of which is error rate correction during the preparation, manipulation, and measurement of quantum bits inside of a quantum computer. The current belief is that error correction must be under 1 percent for any such machine to be viable—as the rate goes up, so too does the number of qubits involved in just that process, leading eventually to an untenable situation.
Read more at: Phys.org