Chilling out with Rubidium: closer and closer to absolute zero

Summary:This news isn’t going to rock your desktop world any time soon, but it could reveal yet more exotic states of matter that might one day play a part in a quantum computer. Apart from that, it is also very, very cool.

This news isn’t going to rock your desktop world any time soon, but it could reveal yet more exotic states of matter that might one day play a part in a quantum computer. Apart from that, it is also very, very cool. Literally, and metaphorically.

Researchers at Harvard University have developed a new way to cool the ultracool - dubbed orbital excitation blockade. The technique could allow scientists to chill quantum gases to within slivers of absolute zero, or -273.15 degrees Celcius.

At these tiny temperatures, the researchers say, quantum gases have the "ultralow entropies required for quantum simulation of strongly correlated electron systems" as well as providing a structure for implementing a two qubit gate in a quantum computing architecture, as per the article abstract here.

Chilling out this thoroughly is a three stage process: laser cooling, followed by evaporative cooling and finally the new process; the orbital excitation blockade.

To start this process, you need to trap your already super-cooled rubidium atoms in an optical lattice. Atoms that collide will influence each other’s orbital excitation, or energetic state, in a way which depends on the depth of the optical lattice; something the researchers can control.

"A sequence of reversible OEB-based quantum operations isolates the entropy in one part of the system and then an irreversible step removes the entropy from the gas," the researchers explain in the paper.

What this means, roughly, is that sequentially, the atoms bump into each other and suppress the excitation of other atoms. The atom with the most energy left is removed, leaving behind a lattice of cooler atoms.

In principle, this can get a quantum gas to within hundredths of a billionth of a degree above zero degrees Kelvin. In practice, the researchers need still finer control of their lattice depth, and that needs better lasers.

The researchers told LiveScience that the research could create new exotic states of matter, and that the perfect arrays of atoms would make "a great starting point for a general purpose quantum computer".

Topics: Graphene

About

Lucy Sherriff is a journalist, science geek and general liker of all things techie and clever. In a previous life she put her physics degree to moderately good use by writing about science for that other tech website, The Register. After a bit of a break, it seemed like a good time to start blogging about weird quantum stuff for ZDNet. An... Full Bio

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