China has developed the world’s most powerful quantum computer. It is capable of performing a task 100 trillion times faster than the world’s fastest supercomputer. In 2019, Google built the first machine that achieved quantum supremacy, i.e., the first to outperform a supercomputer. The Chinese team reported their device, named Jiuzhang, is 10 billion times faster than Google’s.
A quantum computer works on the principles of quantum mechanics. While a classical computer performs calculations using bits that can be either 0 or 1, a quantum computer uses qubits that simultaneously have many states. These qubits can be created using electrons, atoms, photons, or even molecules.
To test Jiuzhang, researchers assigned it a task known as Gaussian Boson Sampling. In this task, the computer had to calculate the output of a complex circuit that uses light. That output is expressed as a list of numbers. Success is measured in terms of the number of photons detected. Jiuzhang detected a maximum of 76 photons in one test and an average of 43 across several tests. The time taken by Jiuzhang to perform this task was 200 seconds. The fastest Chinese computer would have taken 2.5 billion years to arrive at the same result. That suggests the quantum computer can do GBS 100 trillion times faster than a classical supercomputer.
This does not mean China has built a fully functional quantum computer.
China’s quantum computer was developed to perform a particular type of task. There are a lot of challenges to build a practical quantum computer. Firstly, the qubits must be created and stored at a temperature close to absolute zero. The computers must be isolated from atmospheric pressure and Earth’s magnetic field.
A practical quantum computer would also pose a threat to cybersecurity as it can decrypt the widely used encryptions in just a few seconds. Quantum computers can store enormous information, thanks to the laws of quantum physics. A 500-bit quantum computer can store more amplitudes than there are atoms in the universe. Companies like Google, IBM, and Alibaba have invested heavily in quantum computing.