Quantum mirage

Quantum mirage

In physics, a quantum mirage is a peculiar result in quantum chaos. Every system of quantum dynamical billiards will exhibit an effect called scarring, where the quantum probability density shows traces of the paths a classical billiard ball would take. For an elliptical arena, the scarring is particularly pronounced at the foci, as this is the region where many classical trajectories converge. The scars at the foci are colloquially referred to as the "quantum mirage".

The quantum mirage was first experimentally observed by Hari Manoharan, Christopher Lutz and Donald Eigler at the IBM Almaden Research Center in San Jose, California in 2000. The effect is quite remarkable but in general agreement with prior work on the quantum mechanics of dynamical billiards in elliptical arenas.

Quantum corral

The mirage occurs at the foci of a quantum corral, a ring of atoms arranged in an arbitrary shape on a substrate. The quantum corral was demonstrated in 1993 by Lutz, Eigler, and Michael Crommie, now a professor at the University of California, using an ellipitical ring of cobalt atoms on a copper surface. The ferromagnetic cobalt atoms reflected the surface electrons of the copper inside the ring into a wave pattern, as predicted by the theory of quantum mechanics.

The size and shape of the corral determine its quantum states, including the energy and distribution of the electrons. To make conditions suitable for the mirage the team at Almaden chose a configuration of the corral which concentrated the electrons at the foci of the ellipse.

When scientists placed a magnetic cobalt atom at one focus of the corral, a mirage of the atom appeared at the other focus. Specifically the same electronic properties were present in the electrons surrounding both foci, even though the cobalt atom was only present at one focus.


IBM scientists are hoping to use quantum mirages to construct atomic scale processors in the future.

The term quantum mirage refers to a phenomenon that may make it possible to transfer data without conventional electrical wiring. Instead of forcing charge carriers through solid conductors, a process impractical on a microscopic scale, electron wave phenomena are made to produce effective currents. Leading the research are physicists Donald Eigler, Hari Manoharan, and Christopher Lutz of the IBM facility in San Jose, California.

All moving particles have a wavelike nature. This is rarely significant on an everyday scale. But in atomic dimensions, where distances are measured in nanometer s (nm), moving particles behave like waves. This phenomenon is what makes the electron microscope workable. It is of interest to researchers in nanotechnology , who are looking for ways to deliver electric currents through circuits too small for conventional wiring.

A quantum mirage is a spot where electron waves are focused so they reinforce each other. The result is an energy hot zone, similar to the acoustical hot zones observed in concrete enclosures, or the electromagnetic wave focus of a dish antenna . In the case of electron waves, the enclosure is called a quantum corral. An elliptical corral produces mirages at the foci of the ellipse. A typical quantum corral measures approximately 20 nm long by 10 nm wide. By comparison, the range of visible wavelengths is approximately 390 nm (violet light) to 750 nm (red light). One nanometer is 10 -9 meter, or a millionth of a millimeter.