The Joint Quantum Institute published a recent paper detailing a quantum computer constructed with five qubits formed from trapped ions. The novel architecture allows the computer to accept programs for multiple algorithms.
Quantum computers make use of qubits and trapped ions–ions confined with an electromagnetic field–are one way to create them. In particular, a linear radio frequency trap and laser cooling traps five ytterbium ions with a separation of about 5 microns. To entangle the qubits, the device uses 50 to 100 laser pulses on individual or pairs of ions. The pulse shape determines the actual function performed, which is how the device is programmable. The operations depend on the sequence of laser pulses that activate it.
Because of the nature of quantum physics, each pulse has about a 99% chance of doing the right thing, so when you do 100 in a row, you have between a 70 and 90% chance of success. Among the algorithms implemented by the computer, researchers ran a QFT (quantum Fourier transform) which requires two qubit gates between all possible pairs of qubits.
The strength of quantum computing is the massive parallelism that is possible. However, this particular computer is relatively slow per operation (microsecond gate times).
If you have a spare hour, you might enjoy watching the video below from [Andreas Dewes] about the practical realization of some different quantum computers, including those using ion traps and superconducting. We’ve talked about quantum physics before. If you think that entangling particles is out of reach to the average hacker, you might be surprised.