Quantum researchers test Born’s rule

from a Waterloo Media Relations news release

A research team led by scientists at Waterloo's Institute for Quantum Computing (IQC) has earned prominent billing in the renowned journal Science for breakthrough research in quantum mechanics.

In their Science paper, published July 23, the researchers reported on tests on Born’s rule, one of the fundamental axioms of quantum mechanics, following nearly three years of experiments in IQC’s quantum optics laboratory.

"This is the first-ever experiment of its kind that tests Born’s rule in such a dedicated and precise fashion," said IQC director Raymond Laflamme (centre in photo), who inspired the groundbreaking work.

"This research is of fundamental importance because it reveals how nature really works at the atomic scale and it contributes to the ongoing quest for a unified theory of quantum mechanics and gravity."

Quantum mechanics depicts the world of atoms and molecules, solid state physics, and particle physics. It has led to important technologies such as magnetic resonance imaging (MRI), the laser, and the transistor, and could spark new ones such as quantum computers and quantum cryptography.

Born’s rule, which gives the probability that a measurement on a quantum system will yield a given result, is widely assumed to always hold true. This assumption is what prompted physicist W.H. Zurek to once remark, “If Born’s rule fails, everything goes to hell.”

The research team led by Urbasi Sinha (right), a postdoctoral fellow at IQC and a member of Waterloo’s physics and astronomy department, sought to find out if everything could indeed go to hell. "What is amazing is that even though more than 50 years has passed since Max Born put forward his rule, there has not been a single, dedicated, precision test directly for Born's rule," Sinha said.

“In today's world, when there are so many efforts to understand if quantum mechanics is in fact in its final form, it becomes very important to put its main postulates to precision tests."

The researchers devised a variation to the famous "double-slit" experiment, which has long been used to demonstrate the counter-intuitive laws of quantum mechanics. Sinha’s team created a “triple-slit experiment.”

If the photons in the experiment showed any unexpected results, it would mean quantum mechanics is only approximate, just as the double-slit experiment showed that classical physics is only an approximation to the true laws of nature. Even a small violation of Born’s rule would change physics as we know it, implying even more generalized versions of quantum mechanics, possibly leading to new ideas such as “super quantum computing.”

In the groundbreaking triple-slit experiment, researchers were able to provide a bound on the validity of Born's rule, thus ruling out higher-order interference effects up to that bound. The result affirms quantum mechanics as a pillar of modern physics and opens up new avenues for exploring the fundamentals of quantum mechanics.

The article, “Ruling out Multi-Order Interference in Quantum Mechanics,” is online in Science, 23 July 2010: Vol. 329., no. 5990.

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Friday's soaker floods campus buildings

Friday morning’s cloudburst was a once-in-a-decade storm, reports the University of Waterloo Weather Station. In just half an hour, between 7:45 and 8:15 a.m., 35.4 mm of rain fell – on ground already saturated with the previous night’s rain. “Although that was definitely the peak of the event,” says station co-ordinator Frank Seglenieks, “between 7 and 9 a.m. we got around 50 mm.”

The result was flooding across Waterloo Region, with storm drains unable to handle the volume of water and creeks overflowing their banks. On the Waterloo campus, water came bubbling up into quite a few buildings, including Central Stores (where it actually flowed in over doorsteps, despite staff members’ valiant efforts to push it out with brooms), Engineering 2, Carl Pollock Hall, Ron Eydt Village, Mackenzie King Village, and more. In the PAC and Coutts Hall, overwhelmed roof drainage pipes broke.

Luckily, just the week before, the campus’s catch basins – traps to prevent blockages in sewers – had been cleaned out. If not for that, the flooding would have been worse, says Neil Stewart of plant operations. On the other hand, some drains near construction sites, such as Engineering 5 and the Quantum-Nano building, had been covered with filter cloth to screen out construction debris. The filters diverted water into nearby roadways and parking lots, creating muddy lakes at Central Stores and Needles Hall. The filters were quickly removed.

By noon the water had mostly subsided, and the mopping up and repair work began, continuing through the weekend. As of this morning, Stewart says, things are almost back to normal.

From Twitter, here are a few of many tweets about “Rainmageddon”:
Thanks to #starbucks at King/University in #waterloo for getting me a towel while I ordered. • Waterloo is underwater. Roads are flooded. Was driving and felt like saying "I'm on a boat". • Kind of bummed that I'm missing out on Rainmageddon in Waterloo. • It's apparently monsoon season in Waterloo • So this is how Waterloo got its name. • Students were riding the waves from Health Services pond to Grebel at #uWaterloo. • Beware of flooded tunnels! Bout a half inch of water on the floor between SCH and ENV at #uwaterloo.

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Biology film festival; eye research; SDE student design exhibit

from Joanna Magee, Faculty of Science

With the end of spring term looming over the heads of students, professor Susan Lolle likes to add a little bit of fun to her Biology 120 course. On the last day of class, Lolle will host a biology film festival featuring short films made by her students as part of their final lab exercise. “Students need a creative outlet,” Lolle says. “And the videos are like experiments in their own way.”

It’s also an opportunity for some of the plants in the lab, like this phlox, to be film stars. (Photo: Janet Waite, course technician.)

The one-minute films must focus on a plant module, such as response to gravity (gravitropism), plant response to touch (thigmotropism), or how sunflowers move in response to a light source (phototropism).

Students are also free to add photo stills, music, and animation to their videos. “This final project is supposed to be fun and the students really enjoy it,” Lolle says. “I am always impressed at what they come up with.”

The seventh semi-annual biology film festival will be held on Tuesday, July 27 at 10:30 a.m. in B2 350, complete with popcorn. The next festival will be held in Simon Chuong’s class during the winter term.

Lolle welcomes all in the university community to attend. “It’s entertaining and funny, and shows you how students use technology and science in an interesting way.”

Participants wanted for eye research

Dr. Natalie Hutchings and Dr. Patrick Quaid, optometry, are conducting a research study on measuring the anterior chamber depth of the eye. They are looking for study participants between the ages of 30 and 70 of Chinese, Southeast Asian, or Caucasian backgrounds for a maximum 40-minute appointment. For more information, see Dr. Hutchings' lab website, call 519-888-4567, ext. 38118, or email hutchingslab@gmail.com. This study has been reviewed and received ethics clearance through the Office of Research Ethics.

SDE students design for sustainability

“Eleven student groups in a third-year systems design engineering course will present an exhibition of product designs that tackle energy harvesting and sustainability, making use of ambient and wasted energy sources for uses that address current shortcomings in the home,” says an invitation sent by SDE professor John Zelek, who supervises the students. The exhibition takes place Tuesday, July 27, 1 to 3 p.m., in Davis Centre room 1301 (the Fishbowl). Designs address a variety of problems, including "generating energy from human waste... generating energy from computer input devices and wheelchairs, creating light sources for the Third World," and more.

CPA staff

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