The crafty chemist

Practical Quantum Computers Creep Closer to Reality

As they seek to create larger quantum systems, scientists have tried to incorporate some of the same systems-engineering concepts that are used in conventional computers, but the equivalent quantum systems have proved elusive—until now. ”These machines are very fragile,” says Haroche. ”The coupling to their environment causes decoherence, which destroys the quantum features required to achieve their tasks. Correcting the effects of decoherence is thus a very important aspect of quantum information. One possibility is to control the quantum machine by quantum feedback.”

 Yet therein lies a challenge: In the quantum world, the mere act of observing photons or atoms perturbs their motion and changes their positions and velocities—and therefore the value the qubit holds. So for quantum feedback to work, one must be able to observe the system by performing ”weak measurements*,” perturbing it only minimally, and the computer must take the perturbation into account before applying the correction.

The most complex algorithms performed so far have used a quantum computing system based on trapped ions, but Biercuk says the superconducting system is quickly catching up, and that’s ”extremely exciting.”

 

If quantum physics wasn’t so crazy; things would be so much simpler, but then that’s where all the stange and wonderful things in the universe happen. 

(Source: technotalk)