Jiuzhang ( zh, 九章) is the first photonic

quantum computer Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though ...

to claim

quantum supremacy In quantum computing, quantum supremacy or quantum advantage is the goal of demonstrating that a programmable quantum device can solve a problem that no classical computer can solve in any feasible amount of time (irrespective of the usefulness of ...

. Previously quantum supremacy has been achieved only once in 2019 by Google’s Sycamore, however Google's computer was based on superconducting materials, and not photons. Jiuzhang was developed by a team from

University of Science and Technology of China A university () is an educational institution, institution of higher education, higher (or Tertiary education, tertiary) education and research which awards academic degrees in several Discipline (academia), academic disciplines. Universities ty ...

(USTC) led by

Pan Jianwei Pan Jianwei (; born 11 March 1970) is a Chinese quantum physicist, university administrator and professor of physics at the University of Science and Technology of China. Pan is known for his work in the field of quantum entanglement, quantum inf ...

and Lu Chaoyang. The computer is named after ''

Jiuzhang suanshu ''The Nine Chapters on the Mathematical Art'' () is a Chinese mathematics book, composed by several generations of scholars from the 10th–2nd century BCE, its latest stage being from the 2nd century CE. This book is one of the earliest sur ...

'', an ancient Chinese mathematical classic. On 3 December 2020, USTC announced in ''

Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence for ...

'' that Jiuzhang successfully performed Gaussian boson sampling in 200 seconds, with a maximum of 76 detected photons. The USTC group estimated that it would take 2.5 billion years for the

Sunway TaihuLight The Sunway TaihuLight ( ''Shénwēi·tàihú zhī guāng'') is a Chinese supercomputer which, , is ranked fourth in the TOP500 list, with a LINPACK benchmark rating of 93 petaflops. The name is translated as ''divine power, the light of Taihu Lak ...

supercomputer to perform the same calculation. In addition to a quantum computational advantage, Jiuzhang has a

Hilbert space In mathematics, Hilbert spaces (named after David Hilbert) allow generalizing the methods of linear algebra and calculus from (finite-dimensional) Euclidean vector spaces to spaces that may be infinite-dimensional. Hilbert spaces arise natural ...

10 billion times larger than Google's superconductor-based

Sycamore processor Sycamore is a quantum processor created by Google's Artificial Intelligence division. It has 53 qubits. In 2019, Sycamore completed a task in 200 seconds that Google claimed, in a ''Nature (journal), Nature'' paper, would take a state-of-the-art ...

, and as such, is harder to simulate classically.

Experimental setup

The setup involves a Verdi- pumped Mira 900 Ti:sapphire laser which is split into 13 paths of equal intensity and then shined on 25 PPKTP crystals to produce 25 two-mode squeezed states. Through a hybrid encoding this is equivalent to 50 single-mode squeezed states. The purity is increased from 98% to 99% by 12nm

filtering Filter, filtering or filters may refer to: Science and technology Computing * Filter (higher-order function), in functional programming * Filter (software), a computer program to process a data stream * Filter (video), a software component tha ...

. The 50 single-mode squeezed states are sent into a 100-mode interferometer and sampled by 100

single-photon detector Photon counting is a technique in which individual photons are counted using a single-photon detector (SPD). A single-photon detector emits a pulse of signal for each detected photon, in contrast to a normal photodetector, which generates an analo ...

s with an efficiency of 81%.

References

{{reflist 2020 in science University of Science and Technology of China Quantum computing Supercomputing in China