Practical quantum computers have been a pipe dream for nerds and geeks around the world for quite some time now. Harnessing the power of atoms and molecules, bits are replaced by qubits and today’s fastest supercomputer is replaced by the PC of the next era in computing. But for the last ten years scientists have had their progress in this field slowed to a standstill and aside from the very basic quantum computers that first appeared at IBM labs in 2001 we haven’t seen anything newer. Without going into too much detail and making your brain explode with explanations of everything I have written and will subsequently write in this article (you can scrape the surface of knowledge involved with quantum computers and qubits at Wikipedia), the big problem scientists have been faced with this past decade has been overcoming the size-to-signal-strength barrier magnetic resonance poses when it comes to molecules.
The idea is to find a molecule that contains atomic nuclei that can be made to spin up or down at slightly different energies. This allows each nuclei to be addressed separately using the technique of magnetic resonance.
This involves placing them in a powerful magnetic field, zapping them with radio waves and then listening for the echo. (Anyone who has had an MRI scan will have had the same treatment.)
The dilemma is posed when you try to get more signal strength out of such molecules. A single molecule produces way too weak of a signal to make any progress with quantum computers and in order to try and compensate for this you have to use large amounts of these molecules, which is not economically viable for any practical purpose. If you try to use bigger molecules to compensate for this signal degradation, what you get is an increase in the number of qubits (good!) but a significant signal strength decrease from each qubit (bad!). So no matter what scientists tried, they were screwed. Until now.
Michael Grinolds and a group of Harvard University fellows published “Quantum control of proximal spins using nanoscale magnetic resonance imaging” on Wednesday. In other words, they believe that they have solved the signal-degradation issue by shrinking “the business end of a magnetic resonance machine to the size of a pinhead,” which is a really big deal when it comes to magnetic resonance machines (duh, common knowledge. Who doesn’t have one of these in their kitchen?). By testing their theories out in nitrogen vacancies in diamond they discovered that they were able to manipulate electrons in such a way that completely curbs the resonance barrier that has been unbroken for the last ten years. And that puts us one step closer towards cracking the quantum computer puzzle…and to finding Schrödinger’s cat, dead and alive.
Source: MIT Technology Review