Quantum supremacy based on rigorous maths

Mauricio (Mauro) Morales Soler grew up in Santiago, Chile, and found science offered a rigorous and systematic response to his quest to make sense of the world.

“I read books on Plato and philosophy as a child and was very curious about how the world works, then in high school became fascinated by science, first with biology and genetics, and then once I studied physics, I wanted to become a physicist.”

“The chance to do something that has practical consequences in the world, really appealed to me,” he says.

It’s a passion that has led to Sydney where Mauro is close to completing a PhD project exploring two key topics - quantum complexity theory, which uses rigorous mathematics to classify how difficult it will be to solve a particular problem; and quantum algorithms, which involves designing an algorithm to solve a problem as efficiently as possible.

This dual focus involves two supervisors, with his work on complexity led by Professor Michael Bremner from the University of Technology Sydney, and his algorithm development supervised by Associate Professor Dominic Berry at Macquarie University.

Sydney Quantum Academy (SQA) is the ideal place for Mauro’s work because he has access to resources and expertise across the four universities that make up SQA’s partnership together with a stimulating community of academics and researchers.

Mauro’s work is supported by an SQA Supplementary Scholarship, which waives international tuition fees, offering extended time on a candidate's primary PhD stipend.

On leaving school, Mauro completed an undergraduate degree in mathematics and physics at Universidad de Chile, the nation’s largest university, doing his final thesis on the physics of materials, then did a subsequent master’s degree on the physics of glass transition.

“The glass transition is not fully understood. An example of this transition is when you heat silica very quickly so the liquid has no time to form a crystalline structure. The atomic structure in the glass looks more similar to the liquid than the solid, he says.

During his master’s degree, Mauro spent a year at the Los Alamos National Laboratory near Santa Fe in New Mexico in 2015, where he worked on this problem using computational simulations and sound waves to assess the dislocation of materials.

Apart from the Los Alamos’ historic association with the Manhattan project, it also hosts some of the world’s biggest computers – and Mauro was fascinated when he was introduced to people working on quantum computing.

Following his master’s degree, Mauro applied for a range of PhD opportunities in quantum research, but with his materials science background rather than quantum. He initially had no success until he was offered a role in Moscow in 2017, at the Skolkovo Institute of Science and Technology Deep Quantum Labs. Here, Mauro could transfer the expertise in modelling he had developed in material science to a role where he could work on quantum problems.

Mauro spent two years in Russia working on and publishing variational algorithms to address the problem of noise in quantum circuits (such as radiation and vibration that interferes with quantum bits or ‘qubits’) that can undermine results. Quantum approximate optimisation algorithms (QAOA) involve an iterative process to improve these results.

With Russia hosting the 2018 World Cup, it was an exciting time to live there, but Mauro became frustrated with the work. “Variational algorithms were super-fashionable at the time, but it was hard to give any rigorous mathematical statement of their performance, “ he says.

In 2019, a Google AI demonstration claimed “quantum supremacy.” Using a 53-qubit quantum computer the researchers solved a problem factoring very large numbers that they argued would take a classical computer 10,000 years to solve.

“This demonstration was based on an area of mathematics called complexity theory, which studies precisely the computational power needed to solve a particular problem, much of it based on work by Mick Bremner at the University of Technology Sydney,” he explains.

On seeing a Twitter post about PhD opportunities at SQA from Professor Bremner, he immediately applied, arriving in Australia at the end of 2019.

Mauro has enjoyed the easy-going nature of Australia, where students can easily approach a professor across a range of different fields, and says Sydney is a great place to do a PhD in quantum technologies as a theorist or experimentalist.

“The variety of topics people are researching here in one city is incredible; people are working in quantum algorithms, in quantum communication, there are people building the actual computers, working in quantum sensing, etc, “ he says.

He is now interested in designing algorithms, such as those using Fermion sampling, which can compute the properties of physical and condensed matter systems and on studying the complexity of doing that.

Mauro’s next step is a postdoctoral research role at the University of Maryland, USA, starting later in 2023.

Reflecting on his career, Mauro says he is now working in quantum theory at the intersection of maths, computing and physics, despite not formally studying quantum theory before beginning his PhD.

“If you really want to break in - you just have to give it a shot,” he says.