Synopsis: An Optical Analog of an Atom in a Quantized Field

The sloshing of light between optical waveguides replicates the quantum-mechanical exchange between an atom and an electromagnetic mode.
Synopsis figure
A. Crespi et al., Phys. Rev. Lett. (2012)

A proper description of the quantum-mechanical interplay between an atom and the electromagnetic modes of a cavity is fundamental to lasers and other quantum systems. In Physical Review Letters, experimenters use optical waveguides to mimic this atom-field interaction, even in a regime where standard theoretical approximations are not valid.

The well-known quantum Rabi model describes the interaction between two energy levels of an atom and an energy ladder representing an increasingly excited electromagnetic-cavity mode (See 29 August 2011 Viewpoint ). Usually, the interaction is weak enough that the model can be simplified to include only energy transfer from the atom to the field or vice versa. But theory suggests new phenomena when this interaction is instead strong.

To create an experimental analog, Andrea Crespi at the Polytechnic Institute of Milan and colleagues used short, intense laser pulses to write parallel, gently curving waveguides of denser material within a silica substrate, where successive waveguides correspond mathematically to an increased excitation of the cavity mode. They made various sets of waveguides, adjusting their properties and spacings to match the energies and coupling appropriate to different model parameters. Looking down on the waveguides showed that light that was launched into the first waveguide (corresponding to an unexcited cavity) sloshed into the other waveguides and back again. With waveguides close enough together, simulating strong coupling, the team confirmed that the light spreads in a way analogous to simultaneous excitation of both atom and field, which doesn’t happen in the familiar “Rabi oscillations.” – Don Monroe


Announcements

More Announcements »

Subject Areas

OpticsQuantum Physics

Previous Synopsis

Next Synopsis

Quantum Information

Quantum Testing

Read More »

Related Articles

Viewpoint: A Close Look at the Fermi-Hubbard Model
Quantum Physics

Viewpoint: A Close Look at the Fermi-Hubbard Model

The engineered simplicity of a cold-atom system described by the 2D Fermi-Hubbard model allows for a precision test of the model’s equation of state. Read More »

Focus: Water Molecule Spreads Out When Caged
Quantum Physics

Focus: Water Molecule Spreads Out When Caged

Water molecules confined in nanochannels exhibit tunneling behavior that smears out the positions of the hydrogen atoms into a pair of corrugated rings. Read More »

Synopsis: One-Way Quantumness
Quantum Physics

Synopsis: One-Way Quantumness

Experiments provide evidence for one-way quantum steering—an effect by which distant entangled systems can influence one another in a directional way. Read More »

More Articles