Tiny particles:
Quantum leaps

By Chris Rodley

Michael Biercuk’s research into quantum computing may one day help revolutionise our energy use.

Michael Biercuk is doing something that very few people will have the opportunity to do in their lives. The researcher is performing experiments at the absolute limits of human knowledge – and he cannot hide his excitement. “The understanding that you’re doing something that no-one has ever been able to do before is incredibly motivational,” he says.

Biercuk is an experimental physicist who works in the realm of quantum physics, which governs the behaviour of objects down to, and below, the scale of single atoms. In his subatomic world, particles sometime behave in ways that defy common sense, such as existing in two places at once.

Image of Michael Biercuk

For most people this strangeness is a source of wonder but for Biercuk, it represents a practical opportunity. Working from his Quantum Control Laboratory in the University’s School of Physics and the Centre for Engineered Quantum Systems, he and his colleagues are seeking ways to harness the bizarre effects of quantum physics to enable a new generation of technologies.

Most of the technologies we use in the information age, including the microchips in our computers, rely in some way on our understanding of quantum physics. “But these devices don’t take advantage of the most exotic predictions in quantum theory,” says Biercuk. “The next step is to actually build technologies based on these counterintuitive phenomena.”

Some advanced equipment, such as the atomic clocks that power the GPS system, already utilise these effects but it is likely to be just the beginning. A revolution in quantum technology is coming and at its forefront is Biercuk and his team, whose focus is on quantum computing.

While conventional computers encode information as bits that can either be one or zero, quantum computers store and process data in the form of qubits, which can either be one, zero or both states simultaneously. The capacity of tiny particles to exist in two states at once gives quantum computers the potential to drive enormous advances in information processing power.

Together with collaborators from the US National Institute of Standards and Technology (NIST), Georgetown University and South Africa’s Council for Scientific and Industrial Research, Biercuk has helped develop a special kind of quantum computer called a quantum simulator, which made global headlines when the first performance results were announced in April this year.

Its purpose is to simulate the behaviour of natural systems that are far too complex to be analysed by conventional modelling. “It’s like testing a model of an airplane wing in a wind tunnel to understand how a full-scale aircraft will behave,” he explains.

Image of train

The frontiers of science have long captured the imagination of Michael Biercuk, 33, who recalls being engrossed by TV documentaries on the Big Bang around the age of five. He maintained his interest in science at high school and enrolled in a pre-medicine degree at the University of Pennsylvania with the intention of becoming a doctor. However, he became frustrated with what he saw as the limited scope for innovation in a pre-medical degree and one day simply got up and walked out of his organic chemistry class: “I realised that if this was what was required to be a medical doctor, it wasn’t the right career for me,” he says.

He transferred into the field of condensed matter physics and began studying the new material of carbon nanotubes; his undergraduate thesis on the heat conductivity of nanotubes and nanotube-based materials has since spawned a flourishing area of research. After completing his PhD at Harvard studying carbon nanoelectronics for quantum information, he worked as a scientific consultant for the US defence funding body DARPA. Not too long after, however, he was lured back to working in the laboratory by the exciting prospect of using trapped ions to advance quantum computing.

Exciting prospects

It has been a steep learning curve for Biercuk, who had to retrain in atomic physics and the science of lasers and optics while a researcher at NIST in Boulder, Colorado, essentially resetting his technical skills. His drive to push himself out of his comfort zone has paid off, however: “It took a huge amount of effort, and I’m still learning now, but it’s been a great switch,” he says.

At the heart of his recent research is a tiny crystal of 300 atoms measuring less than one millimetre across, floating in space within a device called an ion trap. Lasers and microwaves are used to manipulate the intrinsic magnetism or spin of the atoms within the crystal, allowing the scientists to make them behave in ways that correlate directly with the interactions between electrons in natural materials. “Add to that the ability to tune the system and a relatively easy way of measuring it, and you’ve got a potentially very powerful computing device,” says Biercuk, who was a senior author on the research paper in Nature which introduced the simulator to the world.

The significance of the invention is its unprecedented computational potential. It can simultaneously process 300 interacting qubits of information; the incredibly complex interactions between qubits makes such a feat impossible on even the world’s most advanced supercomputer. “If you were to construct a standard computer with the same computational capacity as that projected for this device, it would need to be larger than the size of the known universe,” he says.

"Doing something that no-one has ever been able to do before is incredibly motivational."

While other kinds of quantum simulators may one day offer insights into biological processes such as photosynthesis (the conversion of light into energy), Biercuk’s project is specifically designed to study magnetic interactions at the subatomic scale. A breakthrough in this field could hold the key to understanding a range of unusual materials such as superconductors, which conduct electricity with no resistance and can be used to distribute power with no loss of energy, but only when kept at very low temperatures.

“If we can build a quantum simulator that allows for the right kinds of interactions to be programmed in, we hope to gain some insight into the origins of superconductivity in exotic materials,” he says. That application is still a long way off for the team’s simulator, which to date has only run simple test programs. Eventually, however, it may provide insights that help scientists to attack hard problems in materials science, such as engineering superconductors which work at room temperature.

That could pave the way for ultra-efficient energy grids that transmit electricity over vast distances without any loss of power, making it easy to route renewable energy wherever it is needed. Room temperature superconductors might have many other futuristic applications too, such as enabling a new generation of high-speed magnetic levitation trains.

In another project, he has also developed a powerful new technique for making quantum computers less sensitive to error. Unlike conventional digital computers, which can tolerate a high degree of imprecision when interpreting electrical signals as ones or zeros, quantum computers are extremely sensitive to minute errors. Finding a way to reduce these mistakes will be essential if quantum computers are to do useful work.

Building on his previous small-scale experiments, Biercuk has developed existing error suppression techniques into what he calls quantum firmware (the term refers to code that comes pre-programmed on a computer). By adapting mathematical formulas used by engineers to filter out background noise signals, his firmware can efficiently reduce errors to tolerable levels.

Moreover, he has been able to develop techniques that make the firmware compatible with standard control hardware, dramatically simplifying the path to implementing it in large systems. The breakthrough has earned the researcher selection as a finalist for the $10,000 Eureka Prize for Innovation in Computer Science.