Quantum photonic processor passes major milestone in quantum computing

One of quantum computing The most significant milestones have been achieved, with a processor that can be programmed in all of its quantum gates outperforming the most powerful classical computers at a task. “Exceed,” however, understates the achievement, as it took the quantum processor 36 microseconds to perform a task that would take existing supercomputers 9,000 years.

The phenomenon of quantum superposition allows the ones and zeros of classical computers to simultaneously be both. In theory, taking advantage of this should allow quantum computers to perform simultaneous calculations that existing machines must do in sequence, often over impossibly long periods of time. Quantum computing has proven more difficult to implement in practice than in theory, but steady progress has been made.

However, we are still a long way from fully operable quantum computers, so an intermediate goal, known as quantum advantage, was created. Processors will show a quantum advantage when they can beat the best classical counterpart on a well-defined task. a role in Nature claims to have done just that in a task known as Gaussian boson sampling.

To test Gaussian boson sampling, photons of light are sent through a network of beam splitters to be counted at a detector. The computer seeks to reconstruct the probability distribution of the photons based on the number counted and certain attributes. The more photons there are, the longer classical computers will take to perform the necessary calculations to establish the distribution.

The photonic processor described in the new paper, known as Borealit has been used to detect an average of 125 photons in repeated trials, peaking at 219 and easily breaking the previous record of 113.

Its creators, the Canadian company Xanadu, describe Borealis as “the world’s first photonic quantum computer offering full programmability across all its gates and capable of a quantum advantage.” Borealis can also be accessed through the cloud.

Although quantum processors have has been achieved using many different designs, the calculations they have performed have mostly been more like party tricks than serious problem solving. Most have also been riddled with bugsa problem that clearly needs to be addressed.

The sampling of Gaussian bosons is not very important in itself, but it represents a way to measure the progress of quantum computers. It’s one of the first areas where quantum computers should be able to beat classical computers, analogous to chess as a way of testing machine intelligence against humans. That computers beat chess grandmasters did not mean that machines had achieved complete intellectual superiority over humans, but it did mark a milestone on that path. Similarly, it has been considered a major marker for quantum computers to dwarf classical equivalents by something, and Gaussian boson sampling has been considered a leading possibility, now achieved.

Borealis achieved a quantum advantage by passing squeezed light through fiber optic loops that act as delay lines and sort photons by time or arrival rather than direction.

Earlier, more limited examples of quantum advantage have been demonstrated, but only with static gate sequences and only small advantages relative to classical computers. Borealis beats these by a factor of 50 million. Its creators also claim that it is much more resistant to classic phishing attacks than previous quantum computers.

As explained by Dr. Daniel Brod of the Fluminense Federal University, NiterĂ³i, Rio de Janeiro in a accompanying editorial, this does not mean that practical quantum computing is just around the corner. To achieve touted goals in cryptographic cracking or pharmaceutical research, “a quantum computer capable of such tasks would require millions of robust and controllable quantum bits (qubits), whereas current quantum processors have fewer than 100 qubits,” Brod notes.

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