The University of Waterloo’s Institute for Quantum Computing (IQC) expects that sensors able to detect properties at the molecular level will be one of the first realized technologies to come out of the physics-bending research being done there, associate professor Joseph Emerson told the CANARIE National Summit audience this morning.
Quantum sensors operate by the strange laws of quantum mechanics and could achieve the best possible sensitivity, efficiency, and and precision that natural physics would allow. Such a capability could be implemented in fields including oil exploration, precision magnetometry, and for other chemical, biological and medical purposes.
“You can examine at the single molecule level the electric properties of a substance,” Emerson told the crowd. “That’s really novel and really exciting for a wide range of applications, for example the early detection of cancer.”
There are three experimental approaches that IQC is looking at currently: magnetic resonance force microscopy, scanning probe microsocopy with a diamond tip, and neutron interferometry. But before you can even come close to grasping what all those scientific terms mean and how they work, it’s important to become familiar with a couple of basic principles about quantum mechanics, Emerson says.
First of all is the superposition principle. Rather than an object simply being either “here” or “there” as we are used to with the classical model of physics, quantum mechanics opens up a range of other possibilities. In fact, an object could simultaneously be in different and seemingly exclusive states at the same time.
This principle is typically explained using the story of Schrodinger’s cat. A thought experiment that involves a cat in a box, cyanide, and a control mechanism triggered by radioactive decay. This video from the Perimeter Institute was used by Emerson to convey the point.
The other principle you have to wrap your head around is the Heisenberg uncertainty principle. No, it has nothing to do with whether Walt Whitman’s double-life will be uncovered in Breaking Bad – it’s the concept that simply by observing a system, you’re going to cause a disturbance. The trick to understanding it is that just making an observation can impact the information you’re looking at. Contrary to classical physics where we expect to know the exact position and velocity of things at any given time, quantum mechanics says that we can’t know one of those things without impacting the other.
“You can’t open your oven to check on a souffle without causing it to collapse,” Emerson says, giving an analogy.
So now that you understand quantum mechanics, back to the sensors. 
In December 2012, researchers at IQC demonstrated the use of a single quantum bit to create a detector for magnetic fields. Using a type of bit called a flux qubit, which is a sort of artificial atom and is shaped like a small ring just as wide as a strand of spider’s silk and is composed of a superconducting metal with a circuit design embedded into it. The micro-sized device serves as the most sensitive detector of oscillating magnetic fields to date. How sensitive? It can detect a field that is 10 million times weaker than the Earth’s magnetic field. The design could be used to conduct further particle research.
Other methods of designing quantum-scale sensors are also being explored. One involves diamond-tipped probes and laser beams in order to trap atoms. While the research for this is in its early stages and doesn’t seem accessible to most people at its current point, Emerson is optimistic about the future.
“Quantum mechanics is as far as we know the fundamental theory of nature,” he says. “We hope and expect quantum mechanics will impact every aspect of our lives.”
