QUANTUM computing for the masses could come a step closer if tests prove successful on a prototype chip designed to process more quantum data than any previous device.
Quantum computers have the potential to be vastly more powerful than conventional machines because they exploit the rules of quantum mechanics to perform many calculations in parallel. They are difficult to build, however, because quantum information is easily destroyed. The most powerful machines to date can cope with only a handful of quantum bits, or qubits, making them little more capable than a hand-held calculator.
In contrast, the prototype chip built by in Burnaby, British Columbia, Canada, is designed to handle 128 qubits of information. The data is stored in 128 superconducting niobium loops as either a clockwise or an anticlockwise current, representing a 0 or a 1, or as a qubit with both currents at the same time in a quantum superposition. When the information needs to be processed, the individual qubits are manipulated by a magnetic field. To make the entire chip superconduct so that the currents can flow indefinitely without dissipating heat, it is cooled to 0.01 °C above absolute zero.
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Because superconducting circuits are relatively large, they are easier to manufacture than other types of quantum devices, which manipulate single electrons or photons and so need to be much smaller. “It can be built using standard semiconductor approaches,” says , chief technology officer of D-Wave. In addition, the method of computation, called adiabatic computing, does not use logic gates, further simplifying the design.
Adiabatic computing begins with a human programmer identifying a quantum system that can mathematically represent the problem at hand. A quantum computer can then solve the problem by reproducing this system using the quantum information it contains.
The team has already tested a 28-qubit version of the system as a proof of concept. In this version, each niobium loop had to be controlled separately from outside the chip. To be able to scale the chip up to 128 qubits, the control circuits are now built-in. If successful, this method could allow D-Wave to create the world’s first commercial quantum computer.
Concrete results will be needed to convince the sceptics, however. “Nobody knows yet whether adiabatic or non-adiabatic quantum computers will ever work,” says , who studies quantum computing at the University of Groningen in the Netherlands. He agrees that the process might be viable, but says he is reserving judgement on whether it actually works until the team publish the test results in a peer-reviewed journal.
