Recently, those at the forefront of the race to realise the potential of the first quantum computer have started to signal that within the next half decade a functional quantum computer will be here 鈥� a machine capable of undertaking tasks unimaginable in the context of today鈥檚 classical supercomputers. Todd Holmdahl, head of Microsoft鈥檚 quantum team, .
Claims were first made a number of years ago that within five years the vast potential of quantum computing would be realised. As we saw with the rise of digital computers, timelines are volatile and uncertain, with developments often taking longer than predicted.
However, there are good reasons to think we could be on the cusp of the greatest computing revolution to date, even if it is not done and dusted in exactly five years.
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Why is quantum computing worth pursuing? These machines are powered by quantum bits, or qubits. Unlike a digital bit, which can only be on or off, a qubit can be 鈥渙n鈥� or 鈥渙ff鈥�, both 鈥渙n鈥� and 鈥渙ff鈥� and neither 鈥渙n鈥� nor 鈥渙ff鈥�. When entangled with other qubits, quantum technology allows for exponentially more processing than its binary counterpart.
The quantum advantage, or so-called 鈥�quantum supremacy鈥�, means creating a computer powered by qubits that goes beyond the powers of current classical computers. To achieve this, a system would need to function with between 50 and 100 qubits in superposition.
When not if
Until very recently, quantum computing sounded like the stuff of science fiction, and yet we are edging closer to it becoming reality as scientists and companies make significant investments to bring the next leaps forward. Now, the pathways towards quantum supremacy have emerged. The real question is not if quantum computers will arrive, but what form they will take. It is here that talk of a revolution needs to be realistic.
It is important to recognise that in terms of reaching quantum supremacy, we are at a stage where no one horse will win the race. There are multiple races and different feasible approaches to building a quantum computer.
Superconductors, ultra-cold atoms and ultra-cold ions are among the approaches that can be used to create or simulate qubits, and each has unique properties. This means researchers face a choice in how to create accurate and scalable quantum processing systems.
Each brings challenges. Ultra-cold atoms promise greater scale, but have yet to produce the required qubit accuracy (too many errors in quantum computation destroys the quantum advantage over standard computers).
Conversely, ultra-cold ions provide reduced errors, but, despite efforts to achieve scalability beginning to be realised, the current limit is 10 to 20 qubits. And the use of superconductors to simulate qubits relies on advances in cutting-edge materials science.
The big players
Over the next five years, all three approaches will be used by different players to make advances. The significant investments by IBM, Google, Intel and Microsoft show that they think this technology can provide a key step change and drive growth.
As we generate increasing data, current computers are reaching their processing limits. This is where we will see the greatest advantages of quantum computers. From modelling climate change, weather systems and population dynamics, quantum-powered capabilities will be able to solve problems classical computers can鈥檛.
Quantum鈥檚 early commercial promise is already being seen: the quantum clock is so precise that it only loses a second in around 4 billion years.
And this is just the beginning: over the next few years, quantum鈥檚 early promise will expand and we will see further applications of the most powerful computer allowed by the laws of physics. Five more years to the revolution? There are grounds for optimism for specialised applications. Just don鈥檛 expect a quantum PC on your desk in 2023.
Read more: Quantum computers: The world鈥檚 first buyers鈥� guide
