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Spotlight Live: Hey Einstein, It Really Is a Quantum World

NOTE: Thanks to everyone who joined our discussion. AN INDEX OF QUESTIONS is listed below.

WHAT KIND OF UNIVERSE DO WE LIVE IN? Dutch physicist Ronald Hanson has given us the best answer to that question to date. And Albert Einstein wouldn’t like it.

The question revolves around a phenomenon called quantum entanglement, which predicts that changing one particle instantaneously changes the other—even if they are on opposite sides of the galaxy, 100,000 light-years apart.

Einstein called this idea “spooky action at a distance.” And he dismissed it, arguing that nothing could move faster than light, so entanglement couldn’t be real. Instead, he proposed that unknown “local factors” must determine the strange properties of these so-called entangled particles.

So how did Hanson prove him wrong? He conducted an experiment that builds on the work of a physicist named John Bell. In the 1960s, Bell argued that Einstein’s theory could be tested by separating a pair of entangled particles far enough so that local forces could not act on both of them at the same time and seeing how often their properties correlated. Physicists would also have to take enough measurements to prove their results were statistically valid.

Hanson is the first to conduct an experiment that does both. It is the strongest proof of quantum theory to date.

His conclusion raises all sorts of questions about the nature of the universe: What physical mechanism entangles particles? How do they communicate faster than light? If it works with an electron, why not a chair? What does this say about the structure of our universe?

Quantum entanglement also has a practical side. It could be used in communications, computing, and especially, cryptography. It might provide a physical basis for protecting privacy in ways that can never be broken.

On Thursday, Nov. 5 The Kavli Foundation hosted a Google+ Hangout to learn more about our surprising quantum universe, and how we can turn theory into practical engineering.

Ronald HansonRenato RennerAlan Brown
 

About the Participants (left to right)

  • RONALD HANSON – is the Antoni van Leeuwenhoek Professor at Delft University of Science and Technology and a member of the school’s Kavli Institute of Nanoscience. He has conducted the strongest test of quantum entanglement yet.

  • RENATO RENNER – heads the Swiss Federal Institute of Technology (ETH), Zurich’s Institute for Theoretical Physics and the Quantum Information Theory (QIT) Group. He is a leader in applying quantum physics to data security.

  • ALAN BROWN (moderator) – is a freelance journalist and writer who specializes in science, engineering, and technology. He has been covering nanoscience and nanotechnology for more than 25 years.

Questions

  • What do we mean when we say a particle is entangled? (2:20)
  • Is there a physical mechanism linking the particles together? (4:15)
  • Is something moving faster than light in this experiment? (5:40)
  • What makes this quantum behavior possible? (7:20)
  • What is Bell's inequality? (9:20)
  • How are quantum particles linked through entanglement? (10:55)
  • So these particles do not have any properties until you measure them? (13:05)
  • How can we use entanglement to encrypt data? (15:20)
  • Is quantum security overkill since our current encryption takes an extremely long time to break? (19:20)
  • Are you building a quantum computer currently? (21:35)
  • Is it possible that there is a length scale involved with quantum entanglement? (23:40)
  • What was the second loophole that was closed in your experiment? (25:45)
  • If we can encrypt data using quantum entanglement can we also communicate using the properties? (28:10)
  • How would time dilation effect quantum entanglement? (29:30)
  • Why can we entangle particles but not larger objects? (32:20)
  • If Einstein was around to hear about this experiment what do you think he would say? (36:15)