Synopsis: Waving, one by one

The optical equivalent of electron oscillations in periodic lattices has now been described by a fully quantum mechanical theory.
Synopsis figure

Bloch oscillations occur when electrons are driven by an external field through a periodic potential, such as that of a crystal. The phenomenon is usually interpreted in terms of the electron wave Bragg scattering off the periodic potential, causing the electron to oscillate rather than translate through the lattice. The optical analog of this effect is described in a classical picture as electromagnetic waves bouncing off a periodic structure. Writing in Physical Review Letters, Stefano Longhi of Politecnico di Milano in Italy has now formulated a fully quantum mechanical theory showing that nonclassical light consisting of only particle-like quanta can also produce optical Bloch oscillations.

Longhi considers photonic structures, where the spatial structure of the index of refraction of the material creates energy bands and band gaps analogous to those for electrons in solids, and applies a fully quantized photon field to them. He studies two situations. In the first case, photons interact with a simple singly periodic structure, and the author follows the photon number distribution as a function of distance, finding that the photons undergo Bloch oscillations just like classical particles. In a doubly periodic structure, two photon input states undergo correlated Bloch oscillations, meaning that the photons exhibit bunching and entanglement because the photons can tunnel between two energy bands. Longhi’s results may be applicable to fabricating and analyzing photonic structures useful for achieving more complex entanglements for optical quantum computing. – David Voss


Features

More Features »

Announcements

More Announcements »

Subject Areas

Optics

Previous Synopsis

Cosmology

Cosmic consistency check

Read More »

Next Synopsis

Nanophysics

Spinning on a gold atom

Read More »

Related Articles

Focus: Light Pushes and Pulls
Mechanics

Focus: Light Pushes and Pulls

Two forces coming from a light beam—one based on momentum transfer, the other on thermal effects—drive a tiny gold plate to move in opposite directions. Read More »

Synopsis: Plasma Mirror Mimics Evaporating Black Hole
Gravitation

Synopsis: Plasma Mirror Mimics Evaporating Black Hole

A proposal for using an accelerated plasma mirror to study the black hole information paradox elevates a thought experiment into a potential reality.   Read More »

Synopsis: Getting Plasma in a Twist
Optics

Synopsis: Getting Plasma in a Twist

Laser vortex beams can exchange their optical angular momentum with a plasma from which they are reflected. Read More »

More Articles