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New window into quantum physics opened with superconductivity in LEDs

Date:
March 18, 2014
Source:
University of Toronto
Summary:
Physicists hae proposed a novel and efficient way to leverage the strange quantum physics phenomenon known as entanglement. The approach would involve combining light-emitting diodes with a superconductor to generate entangled photons and could open up a rich spectrum of new physics as well as devices for quantum technologies, including quantum computers and quantum communication.

This image shows Alex Hayat (foreground) in lab.
Credit: NSERC

A team of University of Toronto physicists led by Alex Hayat has proposed a novel and efficient way to leverage the strange quantum physics phenomenon known as entanglement. The approach would involve combining light-emitting diodes (LEDs) with a superconductor to generate entangled photons and could open up a rich spectrum of new physics as well as devices for quantum technologies, including quantum computers and quantum communication.

Entanglement occurs when particles become correlated in pairs to predictably interact with each other regardless of how far apart they are. Measure the properties of one member of the entangled pair and you instantly know the properties of the other. It is one of the most perplexing aspects of quantum mechanics, leading Einstein to call it "spooky action at a distance."

"A usual light source such as an LED emits photons randomly without any correlations," explains Hayat, who is also a Global Scholar at the Canadian Institute for Advanced Research. "We've proved that generating entanglement between photons emitted from an LED can be achieved by adding another peculiar physical effect of superconductivity -- a resistance-free electrical current in certain materials at low temperatures."

This effect occurs when electrons are entangled in Cooper pairs -- a phenomenon in which when one electron spins one way, the other will spin in the opposite direction. When a layer of such superconducting material is placed in close contact with a semiconductor LED structure, Cooper pairs are injected in to the LED, so that pairs of entangled electrons create entangled pairs of photons. The effect, however, turns out to work only in LEDs which use nanometre-thick active regions -- quantum wells.

"Typically quantum properties show up on very small scales -- an electron or an atom. Superconductivity allows quantum effects to show up on large scales -- an electrical component or a whole circuit. This quantum behaviour can significantly enhance light emission in general, and entangled photon emission in particular," Hayat said.


Story Source:

The above story is based on materials provided by University of Toronto. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alex Hayat, Hae-Young Kee, Kenneth S. Burch, Aephraim M. Steinberg. Cooper-pair-based photon entanglement without isolated emitters. Physical Review B, 2014; 89 (9) DOI: 10.1103/PhysRevB.89.094508

Cite This Page:

University of Toronto. "New window into quantum physics opened with superconductivity in LEDs." ScienceDaily. ScienceDaily, 18 March 2014. <www.sciencedaily.com/releases/2014/03/140318140537.htm>.
University of Toronto. (2014, March 18). New window into quantum physics opened with superconductivity in LEDs. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2014/03/140318140537.htm
University of Toronto. "New window into quantum physics opened with superconductivity in LEDs." ScienceDaily. www.sciencedaily.com/releases/2014/03/140318140537.htm (accessed July 22, 2014).

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