On a table of 3 square meters are dozens of lenses and odd devices, with wires suspended above and a machine chirping ceaselessly.
It is a prototype quantum computer developed by about 20 Chinese scientists at the Shanghai-based Institute for Quantum Information and Quantum Technology Innovation of the Chinese Academy of Sciences (CAS).
The "baby" quantum computer, unveiled in early May, is the first quantum computing machine based on single photons that could go beyond the early classical -- or conventional -- computer.
The principle of quantum computing is based on one of the strangest phenomena in quantum physics: quantum entanglement. The ancients would see modern electronic technology as akin to witchcraft; most people today would have a similar view of future quantum computing technology.
Scientists say quantum computing exploits the fundamental quantum superposition principle to enable ultra-fast parallel calculation and simulation capabilities. In normal silicon computer chips, data is rendered in one of two states: 0 or 1. In quantum computers, data can exist in both states simultaneously, holding exponentially more information.
The computing power of a quantum computer grows exponentially with the number of quantum bits that can be manipulated. This could effectively solve large-scale computation problems that are beyond the ability of current classical computers, scientists say.
PHOTON WIZARDRY
Lu Chaoyang, a 34-year-old professor at the University of Science and Technology of China (USTC) and one of the developers of the prototype quantum computer, is nicknamed "the photon wizard."
"You can't find two identical leaves in the world, but we can make two identical photons -- even God couldn't tell them apart. With identical photons, we can produce quantum interference and entanglement," says Lu.
The identical photons are produced by a device called a single photon source. The chirping machine is a refrigerator that keeps the single photon source at a temperature of minus 269 degrees centigrade.
"As a result of technological breakthroughs in 2013, our single photon source is the world's best, as 99.5 percent of the photons it produces are identical. It is ten times more efficient than its counterparts abroad," Lu says.
"Using former technology, the photons were like twins playing in mud -- you could distinguish them by the droplets of mud on their bodies. But our technological innovation makes photons like clean indistinguishable twins."
Since the "baby" quantum computer was born, it has done just one thing: play a "game" named Boson sampling, which was designed to enable a quantum computer compete with a classical computer.
"We can manipulate five entangled photons so the machine defeats the early classical computer," says Lu. In fact, the wizard and his colleagues set a new world record of manipulating 10 entangled photons at the end of 2016.
They aim to realize manipulation of 20 entangled photons by the end of this year.
"Although the 'baby' quantum computer can't even beat the mobile phone in your hand, it's a milestone. The first electronic computer in human history, which is so big that it filled several rooms, is worthless today, but it is of great scientific significance. We have to develop step by step from science to technology and then to application," Lu says.
"When the car was first invented, it was unreliable and uncomfortable compared with the carriage. But cars eventually surpassed carriages as a result of technological progress."
GREEN SHOOTS
Lu's tutor, Pan Jianwei, a CAS academician and a leading quantum physicist, has spent more than two decades researching the manipulation of microscopic particles.
