Joachim Brand is a theoretical physicist and a true explorer. He is drawn to the wildest most untamed realms of physics where the rules we learn at school no longer apply. Joachim refers to these realms as “unsafe” zones. His passion is to establish little islands of order and safety amidst the chaos. His main motivation is curiosity but his intrepid adventures are also laying the foundations for the technological revolutions of the future like quantum computing.
Originally from a small town in Germany, Joachim first came to New Zealand as an undergraduate backpacker with a bike. He spent eight weeks riding around and fell in love with the country. He did his PhD in Quantum Chemistry at Heidelberg University but then discovered the emerging field of cold atoms and switched direction. He was already captivated by quantum theory and this new field would allow him to create and observe almost any quantum phenomena he could think up. Joachim spent his Postdoc at the University of Washington learning everything he could about cold atoms. After that, a four year advanced Postdoc at the Max Planck Institute enabled him to meet and work with many of the world’s leading theorists. Then, looking for some space and quiet to get on with his own work, Joachim applied for a job in New Zealand. Now both he and his wife, who is also a Professor of Physics, are happily settled at Massey University in Auckland. Joachim is the Leader of the Dodd-Walls Centre’s Quantum Fluids and Gases Theme.
Research: Exploring the “Unsafe” Realms of Quantum Many-Body Physics
"There are certain situations, for example, where a quantum vortex can be in two places at once or be spinning in two directions at the same time. According to quantum mechanics this is possible."
There are a few things that make physics problems really difficult. One is when the system gets too big. Another is when quantum effects come into play. Joachim likes the challenge of combining both these difficulties. His speciality is quantum many-body physics - understanding and predicting what will happen when many particles or atoms come together and quantum effects come into play.
In cold atom experiments, physicists have worked out how to make an entirely new state of matter. It is called a superfluid or a quantum fluid. This is when matter stops behaving as independent particles and collapses into a single uniform wave function. Einstein predicted this new state of matter in the 1920s but it has only become possible to create superfluids in the lab over the last twenty years.
Just as Newton discovered laws of classical physics by dropping things and measuring them, physicists are now able to reveal the laws of quantum physics by experimenting with superfluids.
Joachim is particularly interested in emergent phenomena such as quantum vortices, which are like whirlpools that never stop spinning and quantum solitons, tiny tidal waves that never slow down. He develops theories to predict the behaviour of these phenomena and then experimentalists test them out in the lab.
In most situations quantum vortices and solitons behave very much like their classical equivalents, which can be observed in oceans, galaxies and the atmosphere. But every now and then the classical rules do not apply.
“That’s the area that really fascinates me,” says Joachim.
These mind-boggling states are called “superpositions”. They are very rare and finding them is like looking for a needle in a haystack but Joachim is an expert at this.
One of the reasons people are interested in the superpositions of quantum vortices is their possible use as qubits, the fundamental processing units for hugely powerful quantum computers. They could also be used in extremely sensitive measuring devices called interferometers.
"To test a theory for how the universe evolved before the Big Bang. The ideas is that it spontaneously burst into being just like a bubble forms in a glass of champagne or in a pot of boiling water."
But what really fascinates Joachim is the weird and inexplicable nature of the quantum world itself. He wants to understand how things can be in two places at once and when a vortex can spin in opposite directions at once. He would like to find out if it is possible to create these same weird phenomena at a scale large enough to see with our own eyes.
“There is nothing in the current quantum theory that says this is impossible,” says Joachim.
Who knows, could it be possible one day to be literally in two places at once? Or, as Schrödinger posed, have a cat in a box which is both alive and dead at the same time?
Famous Collaborations and Tabletop Cosmology
One of the challenges of being a theoretical physicist is luring experimentalists to test your theories. Joachim has worked with some of the big names in cold atom physics, including Lena Hau, the first person to slow light down to the speed of a bicycle and Lev Pitaevski who worked out the fundamental equations for superfluids. Recently an experimental group at MIT have been testing Joachim’s theory for how quantum solitons travel through narrow channels. The results have generated great excitement in the physics community.
Joachim is also involved in what he calls “tabletop cosmology” experiments. He is currently working with an Australian group. Joachim has formulated the theory and worked out what the initial conditions would have to be. In their lab, the experimentalists are recreating the quantum conditions of the early universe to test it out.