Quiet Pride in Physics Breakthrough at University of Toronto
Let’s take a moment to congratulate Aephraim Steinberg and the international team at the Centre for Quantum Information and Quantum Control at the University of Toronto. Physics World has recognized them for making “the top physics breakthrough of the year” in 2011.
The Steinberg Team’s Physics Breakthrough at U of T
To paraphrase Star Trek’s Scotty, “You cannot break the laws of physics…but you can bend them”.
Steinberg’s Quantum Double Slit Experiment
Steinberg’s team observed the average trajectory of photons going through a double-slit experiment while preserving the interference pattern shown on the screen where these photons hit.
This bends Heisenberg’s Uncertainty Principle without quite breaking it, and opens a new methodology in quantum physics.
Thomas Young’s double-slit interferometer experiment had shown, since 1803, that light behaved as a wave. When light passes through two slits or pinholes (small enough and at the right distance from each other), the result is an interference pattern. We see the same interference pattern from waves coming through two gaps in a breakwater.
Importance of Steinberg’s Quantum Double Slit Experiment
However, if the scientist adds a device to measure “which slit did the photon pass through”, the interference pattern disappears. This led to Heisenberg’s Uncertainty Principle in quantum mechanics, back in 1927. Basically, we cannot measure both the position and momentum of a quantum-sized “object” (photon, electron, proton; not even atoms or molecules) to whatever accuracy we want, in one experiment.
In a “classic” double-slit experiment, measuring the position of the photon at the slit eliminates the expression of the wave-like behaviour that makes the interference pattern on the screen. Instead, the photon behaves like a particle.
Steinberg took a very inaccurate measurement of many photons at the slit of the apparatus, which allowed the interference pattern to form on the screen. By calculating the average of those inaccurate measurements, he achieved a very reliable value.
This “trick” might be used in future quantum experiments where it is important to make more accurate measurements while retaining wave/particle duality.
Congratulations to Steinberg and the team. Feel free to petition Mayor Ford to proclaim a “U of T Physics Day” to further recognize this achievement.
Preview of My “Target Heart Rates” Finale
For those who read DeHaan Fitness, I just performed my own experiment. “Personal Report on Target Heart Rates…” wraps up my series on target pulse rates for exercise. Normally I would publicize it immediately, but Steinberg deserves today’s blog article here.
Tushna Commissariat, Physics World, “The secret lives of photons revealed“, published June 3, 2011, referenced Dec. 17, 2011.
PhysOrg, “U of Toronto experiment named top breakthrough of 2011 by Physics World“, published Dec. 16, 2011, referenced Dec. 17, 2011.