In
physicsPhysics is a natural science; it is the study of matter and its motion through spacetime and all that derives from these, such as energy and force...
, an
atomic mirror is a device which
reflectsReflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...
neutral atoms in the similar way as the conventional mirror reflects visible light.
Atomic mirrors can be made of
electric fieldIn physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. This electric field exerts a force on other electrically charged objects...
s or
magnetic fieldMagnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges...
s, electromagnetic waves
or just silicon wafer; in the last case, atoms are reflected by the attracting tails of the van der Waals attraction (see
quantum reflectionQuantum reflection is a physical phenomenon involving the reflection of a matter wave from an attractive potential. In classical physics, such a phenomenon is not possible; for instance when one magnet is pulled toward another, you do not expect one of the magnets to suddenly Quantum reflection is...
). Such reflection is efficient when the normal component of the wavenumber of the atoms is small or comparable to the effective depth of the attraction potential (roughly, the distance at which the potential becomes comparable to the kinetic energy of the atom).
Discussion
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In
physicsPhysics is a natural science; it is the study of matter and its motion through spacetime and all that derives from these, such as energy and force...
, an
atomic mirror is a device which
reflectsReflection is the change in direction of a wavefront at an interface between two differentmedia so that the wavefront returns into the medium from which it originated. Common examples include the reflection of light, sound and water waves...
neutral atoms in the similar way as the conventional mirror reflects visible light.
Atomic mirrors can be made of
electric fieldIn physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. This electric field exerts a force on other electrically charged objects...
s or
magnetic fieldMagnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges...
s, electromagnetic waves
or just silicon wafer; in the last case, atoms are reflected by the attracting tails of the van der Waals attraction (see
quantum reflectionQuantum reflection is a physical phenomenon involving the reflection of a matter wave from an attractive potential. In classical physics, such a phenomenon is not possible; for instance when one magnet is pulled toward another, you do not expect one of the magnets to suddenly Quantum reflection is...
). Such reflection is efficient when the normal component of the wavenumber of the atoms is small or comparable to the effective depth of the attraction potential (roughly, the distance at which the potential becomes comparable to the kinetic energy of the atom). To reduce the normal component, most atomic mirrors are blazed at the grazing incidence.
At grazing incidence, the efficiency of the
quantum reflectionQuantum reflection is a physical phenomenon involving the reflection of a matter wave from an attractive potential. In classical physics, such a phenomenon is not possible; for instance when one magnet is pulled toward another, you do not expect one of the magnets to suddenly Quantum reflection is...
can be enhanced by a surface covered with ridges (
ridged mirrorIn atomic physics, a ridged mirror is a kind of atomic mirror, designed for the specular reflection of neutral particles coming at the grazing incidence angle, characterised in the following: in order to reduce the mean attraction of particles to the surface and increase the reflectivity, this...
).
The set of narrow ridges reduces the
van der WaalsIn physical chemistry, the van der Waals force , named after Dutch scientist Johannes Diderik van der Waals, is the attractive or repulsive force between molecules other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules...
attraction of atoms to the surfaces and enhances the reflection. Each ridge blocks part of the wavefront, causing
Fresnel diffractionIn optics, Fresnel diffraction or near-field diffraction is a process of diffraction that occurs when a wave passes through an aperture and diffracts in the near field, causing any diffraction pattern observed to differ in size and shape, depending on the distance between the aperture and the...
.
Such a mirror can be interpreted in terms of the Zeno effect. We may assume that the atom is "absorbed" or "measured" at the ridges. Frequent measuring (narrowly-spaced ridges) suppresses the transition of the particle to the half-space with absorbers, causing
specular reflectionSpecular reflection is the mirror-like reflection of light from a surface, in which light from a single incoming direction is reflected into a single outgoing direction...
. At large separation between thin
ridges, the reflectivity of the
ridged mirrorIn atomic physics, a ridged mirror is a kind of atomic mirror, designed for the specular reflection of neutral particles coming at the grazing incidence angle, characterised in the following: in order to reduce the mean attraction of particles to the surface and increase the reflectivity, this...
is determined by dimensionless momentum ,
and does not depend on the origin of the wave; therefore, it is suitable for reflection of atoms.
Applications
- Atomic interferometry
Interferometry is the technique of diagnosing the properties of two or more waves by studying the pattern of interference created by their superposition. The instrument used to interfere the waves together is called an interferometer...
- Atom holography (see also atom laser
An atom laser is a coherent state of propagating atoms. They are created out of a Bose-Einstein condensate of atoms that are output coupled using various techniques. Much like an optical laser, an atom laser is a coherent beam that behaves like a wave. There has been some arguments that the term...
) This was demonstrated by Shimizu and Fujita in 2002.
- Atomic nanoscope
The atomic de Broglie microscope is an imaging system which is expected to provide resolution at the nanometer scale....
See also
- Quantum reflection
Quantum reflection is a physical phenomenon involving the reflection of a matter wave from an attractive potential. In classical physics, such a phenomenon is not possible; for instance when one magnet is pulled toward another, you do not expect one of the magnets to suddenly Quantum reflection is...
- Ridged mirror
In atomic physics, a ridged mirror is a kind of atomic mirror, designed for the specular reflection of neutral particles coming at the grazing incidence angle, characterised in the following: in order to reduce the mean attraction of particles to the surface and increase the reflectivity, this...
- Zeno effect
- Atomic nanoscope
The atomic de Broglie microscope is an imaging system which is expected to provide resolution at the nanometer scale....
- Atom laser
An atom laser is a coherent state of propagating atoms. They are created out of a Bose-Einstein condensate of atoms that are output coupled using various techniques. Much like an optical laser, an atom laser is a coherent beam that behaves like a wave. There has been some arguments that the term...