Tue Mar 11

Quantum technologies are changing our world – what does NZ need to be part of the next revolution?

Written by David Hutchinson, Professor in Theoretical Physics, University of Otago

As part of a major reform of the science sector ^[1], the government plans to set up a research organisation focused on emerging technologies, including quantum technologies.

The first quantum revolution – based on understanding how electrons behave in semiconductors to make computer chips possible – brought us computers and smart phones.

We are now in the middle of the second wave ^[2] of quantum capabilities, which heralds quantum computing ^[3], enhanced sensing systems and secure communication technologies.

New Zealand has a strong history in quantum physics, tracing back to Ernest Rutherford’s pioneering investigations of the structure of the atom ^[4]. More recently, quantum-optics physicist Dan Walls ^[5] made numerous contributions to understanding the quantum nature of light that are now used in precision measurements, including at the gravitational wave detector LIGO ^[6] in the US.

Walls and his co-worker Crispin Gardiner ^[7] established a school of physics in New Zealand that trained many of the world’s leading quantum opticians.

The legacy of this is that New Zealand enjoys an enviable reputation for its contributions to quantum science. But to turn this legacy into a thriving commercial sector, we need sufficient investment to train the next generation of STEM-literate young people and to take the world-leading ideas developed here out to the market.

The weird world of quantum physics

Earlier this month, the United Nations launched the International Year of Quantum Science and Technology ^[8] to mark a century since the initial formulation of quantum mechanics by Austrian theoretical physicist Erwin Schrödinger ^[9] and Germany’s Werner Heisenberg ^[10], of “cat” and “uncertainty” fame, respectively.

The moniker “quantum” comes from another German physicist, Max Planck ^[11]. His assertion was that energy could only come in discrete packets, or quanta, such as the energy in light being made up of photons.

The logical consequence of this, according to Schrödinger and Heisenberg, is that waves and particles are just the extreme limits of how we can view the substance of the world. An electron, which we tend to think of as a particle, can have wave-like properties. Light, which we consider a wave, can also behave like a particle.

Understanding the wave-like properties of electrons is what underpins the electronics industry. Understanding the quantum nature of light gives us lasers and optical-fibre communications technologies.

Close-up of a fiber laser cutting machine cutting a metal sheet, with sparkling light flying off.

Lasers such as this laser cutter, and optical-fibre communications, are some of the technologies developed during the first quantum revolution. Shutterstock/Pixel B ^[12]

However, the technologies we have developed so far are just the beginning. The second quantum revolution utilises the more weird and wonderful consequences of Planck’s seemingly innocuous “quantisation” of energy.

As long as we don’t look, a quantum particle can be in a superposition ^[13] of two states at once.

In Schrödinger’s example, a cat in a closed box could be alive and dead at the same time, until we check. Similarly, as an electron spins around its axis, it can have its spin axis pointing up or down. This two-option system can be used to make bits – the zero and one binary building blocks of all computation.

In the quantum world, a new option is allowed: the superposition of zero and one bits. It turns out that, with this new option available, we can construct some algorithms that are faster than anything available through classical logic. This is the promise of quantum computing, the advent of which is on our doorstep ^[14].

The risks and rewards of quantum computing

Quantum computation offers both benefits and risks. For example, a quantum algorithm set to surpass classical computing is known as Grover’s search algorithm ^[15].

This will speed up the search of vast quantities of information and could optimise logistics, investigations of molecular configurations for drug discovery and myriad other opportunities in computation and design. But it could also compromise privacy and expose people to the attentions of bad actors.

Much of our current information security is based on an encryption system developed in 1977 and known as RSA after the authors of its description (Rivest, Shamir and Adleman). RSA is based on the factorisation of big numbers into their unique prime factors.

RSA2048 is currently unbreakable by modern computers. But a recent survey ^[16] suggested it could be broken in a day by a quantum computer developed within the next 15 years. This would render current encryption for banking and all information exchange obsolete.

New encryption protocols have been developed ^[17] but need to be implemented to protect information and money.

Technical challenges of quantum technologies

Quantum properties can also be used to make sensors for electric, magnetic and gravitational fields, leading to applications in medicine and environmental monitoring, but also military and nefarious activities.

The development of quantum technologies faces huge technological challenges and can only proceed effectively through international collaboration.

However, the very nature of the benefits and risks can lead to protectionism and drive the pursuit of national advantage. Because of this, there is a real threat to access to supply chains and new technology.

It is therefore imperative New Zealand is part of international collaborations developing these technologies. We may not build our own quantum computing facility, but we do provide important niche expertise.

For example, we have capability in the development of quantum memories to store quantum information ^[18] and in quantum transduction (where a quantum state of light can be transferred from one frequency to another) which will be essential for networking quantum computers.

Last month, the OECD published a quantum technologies policy primer ^[19]. This provides an early foundation for governments to understand the benefits and risks of quantum technologies and outlines the policy opportunities and challenges.

It highlights the need for early, anticipatory governance to ensure equitable benefits accrue from these new technologies. And it identifies a critical risk in the looming lack of appropriately skilled young people.

For New Zealand, this stresses the ever growing need for investment to ensure we can train, attract and retain top talent. New Zealand has a solid foundation in quantum science. It is imperative we capitalise on it for the benefit and security of the nation.