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Building a Foundation for a Quantum Technology Industry

Rob_Ballagh_webIt is largely due to Rob Ballagh’s tenacity and vision that Otago University is now a world class centre for quantum technology. Twenty years ago, Rob saw that New Zealand would need to move into experimental research to be competitive long-term on the world stage. We were already renowned for theoretical quantum optics through the pioneering work of Dan Walls and colleagues at Waikato University. However an experimental facility as Rob envisaged would require serious funding and support.

In 1995 Rob hatched an outrageous plan to make a Bose Einstein Condensate (BEC) at Otago. This was a new quantum state of matter, predicted seventy years earlier by Einstein. Scientists in top international labs had been trying for almost a decade to produce a BEC and only one group had succeeded. Amazingly, with a couple of experimentalists and just enough funding, the Otago team managed to make one too. They were the 11th lab in the world, beating Australia and the UK. It was the big result needed to persuade the government to keep funding experimental quantum optics and it enabled Otago to attract top researchers and students.

Now that investment in quantum technology is exploding all around the world, New Zealand is in the race with a head start. We are achieving world first results and training a workforce to grow new high tech industry.

Early days in the Booming Field of Laser Research

One of Rob's most exciting projects was designing an atomic laser. Just as an optical laser produces a coherent beam of light, this would produce a coherent beam of matter.

These atomic lasers have been built and are waiting for a suitable application>

Originally from Christchurch, Rob completed his Honours degree in Physics at Canterbury University. Soon after he won a Fulbright Scholarship to do his PhD at JILA, University Colorado (where years later the first BEC would be produced). This was 1973. The laser had been invented a decade earlier and its discovery threw open the quantum realm for exploration. At JILA, Rob was at the centre of this burgeoning field. Several of his colleagues went on to win Nobel prizes. It was an incredibly exciting time.

Rob specialised in theoretical physics. In his PhD he was investigating the quantum nature of light. A fundamental idea in quantum theory is that light can behave like chunks of energy, called photons. But this idea was very hard to prove. In all experiments up till this point it could be explained by a smooth wave model. Because of its precision and intensity, the laser made it possible to detect the particle nature of light. Coincidentally it was fellow kiwis, Dan Walls and Howard Carmichael, who a few years earlier had developed the theory to show this was possible. Rob was trying to understand the interactions between laser light and atoms, developing models to explain and guide the experiments going on around him.

Returning to Small Town New Zealand

In 1979 Rob accepted a postdoctoral position at Otago University. The invitation came from Jack Dodd who was visiting JILA at the time. Rob arrived to discover rundown labs and very little going on experimentally. Although Jack had put Otago on the map twenty years earlier with his pioneering theoretical work, Jack’s career was winding down and with it the momentum for research.

“It was pretty moribund”, Rob recalled. But he was absolutely determined to make it work. He couldn’t continue with the research he began at JILA which required advanced resources and expertise. So he took a side step into nonlinear optics. This was a new field following the discovery of the laser.

In the past interactions between light and matter had always been linear and could be predicted by simple classical rules. A beam of light could be slowed down by passing it through different materials and refracted or reflected in different directions but its fundamental energy would stay the same - if you shone a red light in, for example, you would always get a red light out. Now the intense laser light was revealing new nonlinear effects - some materials caused laser light to change colour; sometimes clusters of light would stick together or move in unexpected directions. A whole new suite of theoretical models and approaches was required to explain and predict these new experiments. This became Rob’s forte and his theoretical work helped to lay foundations for high speed internet.

“It’s the nonlinear response that makes optical signal processing so dominant and valuable,” he explained. “For example frequency doubling where you can put in one frequency and get out a number of frequencies... Broadly speaking that’s how you can get a lot of signals down a phone line.”

Pioneering Quantum Computation

Rob had always been interested in computers even before they were common in the lab. Now, as more experiments delved into the quantum world, his interest took on new significance. In quantum interactions every part of the experiment is related to every other part which generates hugely complex webs of equations, impossible to solve without computers. Perfectly poised to respond to this growing need, Rob was able to guide and explain the results of experiments throughout the world. Rob’s enthusiasm spread to his colleagues at Otago and computation became a strength of research at the university.

Connecting New Zealand with the World

As soon as Rob arrived back in New Zealand he set about developing international collaborations. This wasn’t easy in the early eighties.

“Remember these were pre-internet days,” Rob said. “I’d write a letter, which took eighteen days to get to JILA. They’d think about it for ten days. So it would be two or three weeks before I’d get a reply. By that time I’d often have forgotten what I was thinking.”

Throughout his career he made continuous efforts to travel and promote his work, developing a network of international connections that later proved key to his group's’ success.

“One thing I learnt in America is that you have to be prepared to push,” Rob explained. “I think that’s something I brought back from JILA. You can’t sit and wait for something to happen. You have to go out and make it happen.”

In New Zealand Rob connected with Dan Walls and his colleague Crispin Gardiner at Waikato University. They were slightly older than Rob and already established with a formidable reputation overseas. Rob learnt a lot about the ‘entrepreneurial’ side of research from Dan who was an expert at picking the right problems and drawing attention to their research. Rob attended their famous summer schools, which attracted Nobel Prize winners and top thinkers from across the world.

Bose Einstein Condensation - Putting Otago on the World Stage

The emergence of Bose Einstein Condensation completely revolutionised the fields of quantum optics and atomic physics. Where the laser had opened the gates to the quantum realm, BECs gave experimentalists the ultimate vehicle to explore it. They made it possible to induce and observe almost any quantum phenomena.

In a BEC the atoms stop acting like individual particles and behave like a single wave. Just as Newton and Galileo worked out the laws of motion and gravity by dropping things, bumping them into each other and measuring the outcomes, experimentalists could play with BECs to work out the theories of quantum physics.

To make a BEC is an incredibly difficult technical challenge. Atoms need to be suspended in space and cooled to temperatures just above absolute zero. This is all done by firing lasers at the atoms. The laser light exerts a force which slows the atoms to a standstill achieving the incredibly cold temperatures required.

It was 1995 when the first BEC was made. Carl Wieman and Eric Cornell at JILA later won the Nobel Prize for the achievement. BECs were the opportunity Rob had been waiting for.

“I was on leave at the time and ready to do something new,” he recalled. “I realised I had the skills to contribute. The level of computation required to describe BECs skyrocketed. There were many people overseas with computational skills but they weren’t in this area. And I happened to be in the right place at the right time.”

Rob was at Oxford University visiting Keith Burnett, an expert in theory of BECs. Keith brought Rob up to speed and they began to collaborate. He also met up with kiwi postdoc Andrew Wilson, a brilliant experimentalist who was equally passionate about BECs. They started exploring the idea of Bose Einstein work at Otago.

“We could see that it would be a huge challenge,” said Rob. “But we were committed to getting some serious world-class physics going in Otago.”

While Andrew completed his postdoc and gathered all the knowledge and contacts he could for the challenge, Rob returned home to raise funds. They secured a grant from the Marsden fund which had just been established to support fundamental research. The head of the Otago physics department immediately backed their proposal and the university’s research committee were very supportive. Friends from all around the world offered advice and support. Behind all this was Rob’s infectious enthusiasm and his refusal to give up.

“The big overseas teams would have had ten people in the lab,” Rob said. “We raised enough money for Andrew and one postdoc. They were an amazing team. When I look back I simply don’t know how it happened.”

Andrew returned to Otago in 1997 and by August 1998 they had done it - they’d made a BEC.

A wave of excitement spread across the country. Rob made sure the TV crews were invited. There were newspaper articles and radio interviews.

This great achievement marked the beginning of a new era at Otago University as a world centre for experimental cold-atom research. Since then the group has expanded, attracting prestigious grants, top researchers and students from around the world. Now, Otago is contributing at top level to the development of quantum computers. One Otago researcher has developed the world's leading quantum memory solution. Another holds the record for controlling individual atoms.

All this was made possible by Rob and Andrew’s almighty step into the dark.

Quantum Whirlpools and Waves of Matter

After the emergence of BECs Rob entered the mind boggling field of atom optics. The basic idea of atom optics is this - if a BEC is a wave then it should act like other waves. In standard optical experiments waves of light are manipulated using lenses, mirrors, beam splitters and prisms. Rob became fascinated by the possibility of doing similar experiments with BECs.

“We started to think about passing a BEC around the equivalent of an optical table and doing all the things you do in optics,” Rob said. “Can you focus it? Can you put it through a beam splitter?”

He collaborated with prominent theorists Crispin Gardiner and Keith Burnett to design the mechanisms to amplify and release the matter waves.

Rob was also a pioneer in the field of quantum vortices - whirlpools that form when a BEC is stirred. These are important for understanding how energy moves in a BEC. It all began at a conference when the Nobel Prize winner Eric Cornell showed slides of quantum vortices. Rob recalls:

“They looked incredibly complicated and Eric said he didn’t know what to do with them. I got in touch and said I think I can calculate that.”

Working with a postdoc Rob was able to explain some of the reasons why vortices behaved that way.

Rob is an explorer at heart and his focus has always been on pure discovery. However, his fundamental theory work has laid foundations for the development of quantum technologies such as quantum computers, atomic clocks and extremely precise position measurement systems. And who knows what else the future will bring.

Nowadays Rob continues to explore the quantum interactions between light and matter, encouraging his students to push the boundaries as he has done.