“The emerging field of atomtronics aims to construct analogies of electronic components, systems and devices using ultracold atoms,” say Ron Pepino at the University of Colorado in Boulder and pals.
Today, they outline their vision for atomtronics, show how it works and explain why it could shape the future of information processing.
The idea is to manipulate neutral atoms using lasers in a way that mimics the behaviour of electrons in wires, transistors and logic gates. Over the last decade or two, physicists at NIST and elsewhere have become masters at creating optical lattices in which atoms can be pushed pulled and prodded at will.
But this kind of optical lion taming has limited appeal so Pepino and co have begun a program to put tame atoms to work.
The problem is that atoms don’t behave like electrons so building the atomtronic equivalent of something even as straightforward as a simple circuit consisting of a battery and resistor in series, requires some thinking out of the box.
Pepino and co say that transferring atoms from one reservoir to another is a decent enough analogy and that this transfer can take place thorugh an optical lattice in which atoms tunnel at a uniform rate. That’s their simple circuit analogy.
What of more complex components? A diode is a device that allows electrons to travel in one direction when a voltage is applied but not in the other when the voltage is reversed. Pepino and co’s atomtronic diode is an optical lattice that connects two reservoirs but with a step-like energy difference in the middle. This allows atoms to tunnel in one direction but not the other.
In a similar way, the NIST team show how it is possible to create various kinds of atomtronic transistors and even an atomtronic AND gate. From there, it is but a short step to atomtronic information processing.
But why bother when we already have components like these that work perfectly well with electrons?
Pepino and pals say there are a number of reasons. Neutral atoms are easy to isolate from their environment and so may turn out to be useful for quantum computing. And unlike semiconductor lattices, optical lattices can be made more or less perfectly. That will allow physicists to test the fundamental properties of logic circuits in a way that is entirely free of unwanted complications. “It is possible that a deeper understanding may feed back to the design of conventional electronic systems and could lead to future improvements,” say the NIST team.
But perhaps the most interesting reason is this: “atomtronics systems are richer than their electronic counterparts because atoms possess more internal degrees of freedom than electrons.”
Until recently, electronics had been based on a single property of electrons–their charge. But in recent years, physicists have begun to exploit a second property electron spin. So-called spintronics promises to revolutionise electronics because it allows information to be encoded in an entirely new way.
Atomtronics could take that even further by offering entirely new ways to mess about with information. Neutral atoms can be fermions or bosons and the interactions between them can be long or short range, strong or weak and attractive or repulsive.
For that reason, atomtronics opens up exciting new ways to store and process information that cannot be done with electrons. Although exactly what there is to gain by this isn’t yet clear.
That will have to wait for a future study. For the moment, Pepino and co appear to be single-handedly driving the field of atomtronics forward. So far their work appears to be largely theoretical. Perhaps they could do with some help to get the first atomtronic devices up and running.
Ref: arxiv.org/abs/1005.3069: Open Quantum systems Approach To Atomtronics