Quantum Chip Brings 9,000 Years of Compute Down to Microseconds

A Quantum Processing Unit (QPU) developed by Toronto, Canada-based Xanadu, has outrageously outperformed a classical system in a computing task. We say outrageously because that's one of the few adjectives that encapsulates the performance difference between both systems: the QPU, named Borealis, completed the computing task revolving on gaussian Boson sampling (GBS) in just 36 microseconds. According to the paper published in Nature, today's algorithms and supercomputers - the highest-performing classical computing systems - would take an inhuman scale of 9,000 years to accomplish the same task. Nevertheless, it is enough for the team to claim the coveted quantum advantage badge of honor.

Remember that the basic unit of quantum computation, the qubit, can simultaneously represent 0 or a 1. The orders-of-magnitude higher performance in specific tasks than their classical counterparts comes from quantum computers not working on exact computation methods. Instead, they describe how probable a solution is - before making a measurement.

Sadly, there's no practical use for the GBS workload; it's one of the possible benchmarks for testing the performance of quantum processing solutions against classical computers, a space that's still teeming with benchmark standardization attempts from players such as IBM. 

Xanadu's Borealis is based on the increasingly relevant photonics field as it applies to computing. Specific quantum computing chips use qubits borne from silicon quantum dots, topological superconductors, trapped ions, and other technologies, with some already employing photonics as scaling mechanisms to create interconnected QPUs.The Borealis QPU is photonics-based through and through, unlocking lightspeed-esque operations through its photon-based qubits. The researchers expect photonics-based quantum computing solutions to ultimately provide the most effective way to scale quantum computers' performance. It is mainly due to the advantages of time-domain multiplexing, which allows for multiple, independent data streams to travel simultaneously masked as a single, more complex signal.

The researchers managed to squeeze as many as 219 photon-based qubits onto the Borealis QPU - although the programmable nature of the gates means that that number isn't fixed, and the mean active number of photons was 129. That's still more than IBM's current Eagle QPU, which features 127 qubits - but the company's roadmap does lay out plans to introduce its Osprey QPU, which packs as many as 433 of IBM's superconducting transmon qubits, later this year.

Another element that allowed for the increased quantum performance of Xanadu's Borealis is that the researchers have designed their system with dynamic programmability on all implemented quantum gates. This base circuitry allows for quantum operations to be performed, employing varying numbers of qubits. The programmable aspect of Borealis' quantum gates thus unlocks an FPGA-like architecture that one can reconfigure according to the task.

The researchers further ensured that the computed solutions to the GBS task were correct, which should settle the debate on whether or not quantum advantage was achieved. Xanadu is now bound to continue developing its solution, showcasing very promising results. 

Ultimately, they'll also have to convert Borealis into a commercially-available solution. However, researchers can already take the QPU for a spin through Xanadu's cloud and Amazon Braket. But the results bode well not only for the future of photonics but also for photonics-based quantum computing and should be one of the technologies to look at until the anticipated explosion in quantum computing capability currently expected by 2030.