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Microsoft is working on a quantum computer that could be part of the Azure cloud in five years’ time.
The company claims it is leading the field in a type of quantum computing called a topological qubit, which it claims is far less error-prone than rival qubit systems.
“We are very close to figuring out a topological qubit. We are working on the cryogenic process to control it, and we are working on 3D nano printing,” said Todd Holmdahl, Microsoft corporate vice-president in charge of quantum computing.
“Competitors will need to connect a million qubits, compared with 1,000 in our quantum computing machine. It is about quality.”
The benefit of quantum computing, according to Holmdahl, is that it can compute much faster than traditional computers.
“Take the RSA-2408 challenge,” he said. “If you have a very long number made up of two prime factors, it would take a billion years to crack on a traditional computer, but with quantum computing RSA-2408 could be cracked in 100 seconds.”
This accelerated processing power occurs because quantum computing changes the way information is stored. “For the last 4,500 years of storing information, it hasn’t changed very much. In a transistor, we store a value of zero or one. With quantum computing you can simultaneously store zero and one,” said Holmdahl.
So, while a classical binary 4-bit computer can hold one of 16 possible binary numbers from 0000 to 1111 (zero to 15 in decimal), Holmdahl said a 4-qubit quantum computer would be able to hold all combinations of binary digits between 0000 and 1111 simultaneously. It is the qubit’s ability to hold multiple numbers simultaneously that enables quantum computers to run algorithms exponentially faster than traditional, binary computers.
Holmdahl said this power could be used in new areas of research, citing quantum chemistry as an example, where it could be used to identify chemical catalysts that can break down greenhouse gases in the Earth’s atmosphere or a catalyst to accelerate the nitrogen cycle to produce artificial fertilisers quicker and in a more energy-efficient way.
“Quantum computing is the technology of our generation,” he said. “It will change the game. You will see courses everywhere.” Holmdahl said it was likely that people who are well-versed in linear algebra will find it easier to program quantum computers. “People steeped in machine learning will also find it easier because the maths is similar,” he added.
The reason Holmdahl believes Microsoft has the edge in quantum computing is because its researchers are close to cracking what is known as a topological qubit. It is also developing a system architecture at the Niels Bohr Institute in Copenhagen, where qubits operate at just above absolute zero, at 30 millikelvin. The extreme cold minimises interference. Microsoft has also created a high-level language Q# for Visual Studio, plus it is working on a quantum computer simulator, which will run locally on a PC or on Azure.
The topological qubit is the centrepiece of Microsoft’s efforts in quantum computing. Work began two decades ago in Microsoft’s theoretical research centre, when mathematician Michael Freedman joined. Freedman is renowned for his research in a field of mathematics known as topology.
According to Microsoft, Freedman began a push into quantum computing 12 years ago, backed by the company’s chief research and strategy officer, Craig Mundie.
At the time, Mundie said quantum computing was in a bit of a doldrums. Although physicists had been talking about the possibility of building quantum computers for years, they were struggling to create a working qubit with high enough fidelity to be useful in building a working computer.
According to Holmdahl, physical qubits are error-prone so it requires roughly 10,000 of them to make one “logical” qubit – which is a qubit reliable enough for any truly useful computation.
Quantum computing researchers have found that if a qubit is disrupted, it will “decohere”, which means it stops being in a physical state where it can be used for computation.
According to Microsoft, Freedman had been exploring the idea that topological qubits are more robust because their topological properties potentially make them more stable and provide more innate error protection.
Holmdahl said a topological qubit would have far fewer errors, meaning more of its processing power could be used for solving problems rather than correcting errors. “The more qubits you have, the more errors you have,” he said. This, in turn, means that more qubits must be connected together.
According to Holmdahl, there is a theoretical limit to how much a quantum computer can scale, due to the complexity of networking all the qubits together and the error handling. “We are taking a different approach. Our error rate is three to four orders of magnitude better,” he said.
Microsoft has begun to apply its quantum computing research to solve real-world problems, according to Holmdahl. For example, it has created a “quantum-inspired optimisation” to work out the lowest traffic flow in Beijing.
“Classical [binary] algorithms go up and down, analysing peaks and troughs in traffic. A quantum particle can be everywhere if it is not measured. We mimic what the quantum world does, and in doing so we can solve the problem faster,” he said.
In effect, the algorithm only processes low traffic signals and discards any peaks in traffic. Holmdahl said the algorithm was able to run on a standard PC and perform the optimisation far quicker than accelerated hardware.
Holmdahl said he expected this technique to become increasingly used to solve computationally challenging problems more quickly, but admitted quantum-inspired optimisation would not solve all problems. “You will need a real quantum computer to tackle quantum chemistry,” he added.
Over the next five years, Holmdahl said we will see the emergence of quantum computing startups and consultants who will be able to help businesses tackle computationally complex problems.