Dr. Pierre-Nicholas Roy puts a new spin on quantum molecular dynamics
By Vanessa Parks
Internal Communications and Engagement Specialist
While filling your water bottle this morning, you likely weren’t thinking about how water could be at the heart of the next supercomputer. But Dr. Pierre-Nicholas Roy most certainly was. Roy is laying the groundwork for water-based quantum processing with his research into the quantum molecular dynamics of water.
Roy’s Tier 1 Canada Research Chair has just been renewed, and he’s looking forward to digging deeper into his team’s most recent discoveries, keeping Waterloo at the top of the quantum field. Typically, that team includes around 10 undergrads, graduate students and postdocs. Most of what they do is mathematical and computer simulation-based, so instead of stocking a more conventional lab, this funding provides for technology and travel to conferences where students can collaborate and learn.
“There’s a promise with quantum mechanics that you can build really fast computers and extremely safe encryption,” says Roy. But when he talks about his research, Roy is careful to be clear that it doesn’t have a direct practical application. “I’m a fundamental theorist, so application is never the goal,” he insists. “We don’t build highways. We clear paths in the woods.”
And those woods can be dense. Roy’s research is in quantum molecular dynamics. In other words, he studies how molecules move at the quantum level. Roy is specifically interested in the water molecule, which his research has shown to have special properties that could be harnessed to store quantum information.
He and his team have recently discovered a quantum phase transition in water. “Water can be vapor, liquid or solid, these are its classical phases, but there are other phases that are important for making quantum materials for applications that could be technological,” says Roy.
When water molecules are encapsulated and prevented from forming hydrogen bonds, they behave in an interesting way. “We have found that water molecules align if they are close together and are disordered when they are far apart,” Roy says. “By being confined, the water molecules can align or not, and it gives them very special electric properties at the scale of nanometers.”
But taking advantage of quantum properties like this can be tricky. Quantum information can be stored when molecules are in a state of coherent superposition, like when water molecules are aligned and entangled, but eventually they return to a state of decoherence and can no longer retain the quantum information. So, the goal is to protect coherence for as long as possible.
“There are different ways to protect coherence, and one candidate in the water molecule is the nuclear spin of the proton,” says Roy. The spin is special because it takes longer for molecules to change their nuclear spin state. “Whereas transitions due to rotations and vibrations usually take picoseconds to occur, spin conversion can take hours,” Roy explains. “So, using nuclear spin and nano-confinement, you can potentially keep quantum information for much longer.”
Nuclear spin conversion will be a key area of the research Roy is continuing with the support of this funding renewal, clearing a path in the woods that may lead to a highway of water-based quantum processing.