Device that behaves like a giant artificial atom
doi:10.1038/nindia.2019.125 Published online 19 September 2019
Physicists have designed a tiny electrical device that behaves in the same way as a giant artificial atom1. This atom could potentially be used in quantum computers as well as to study new aspects of light‒matter interaction.
The physicists from Chalmers University of Technology in Sweden, including Baladitya Suri, who is now at the Indian Institute of Science in Bangalore, India, developed the artificial atom by depositing a thin film of aluminum on a gallium arsenide substrate.
They then excited the atom with microwaves at a temperature close to 0 degree Kelvin. The microwaves generate surface sound waves that propagate slowly through the atom. The atom interacts with the waves the way a natural atom does with light.
The atom, a few hundred micrometers long, is much bigger than the sound waves it interacts with. Hence, such atoms are giant artificial atoms, in contrast to small atoms that interact with light at wavelengths larger their size.
The atom has two coupling points. Sound moves from one point to another in 200 nanoseconds. At each point, the device loses energy by emitting sound waves. However, the energy lost at a point propagates to the other and then gets reabsorbed.
The energy lost into the environment returns to the atom, showing that it can retrieve lost information and it has memory.
Sound-wave-based devices are much smaller in size compared with their light-based counterparts. “Such small size is of great importance, potentially for quantum computers that can store huge data,” says Suri.
1. Andersson, G. et al. Non-exponential decay of a giant artificial atom. Nat. Phys. (2019) doi: 10.1038/s41567-019-0605-6