Scientists blend frequencies in crystal photon cocktail

The future watchers over at io9 have an interesting little snippet about a technique scientists have developed for gradually shifting the frequency of a photon, originally published in Physical Review, Letters.

A photon is a discrete packet of energy. It has a particular frequency and can be absorbed in totality, or not at all. This allows engineers to capture photons of particular energies in detectors, in turn acting as on/off switches, or logic gates.

This, as io9 so elegantly explains, “is useful, but not as versatile as a dimmer”.

So what the Maryland researchers have done is develop a technique for blending the frequencies of two photons of different wavelengths.

The abstract of the research paper explains it as follows: "Here, we experimentally demonstrate the simultaneous wavelength translation and amplitude modulation of single photons generated by a quantum dot emitting near 1300 nm with an exponentially decaying waveform (lifetime ≈1.5  ns). Quasi-phase-matched sum-frequency generation with a pulsed 1550 nm laser creates single photons at 710 nm with a controlled amplitude modulation at 350 ps time scales."

Fortunately, this can be oversimplified as follows: The researchers have a crystal into which they fired infrared photons and a pulsed laser beam at wavelengths of 1300nm and 1550nm respectively. The crystal shuffles the energies around (a technical term, that) until photons with a wavelength at 710nm emerge.

Nifty, we think you’ll agree. Especially as this kind of energy level control could be useful in building the quantum communications networks of the future.