China builds world’s fastest programmable quantum computers that outperform ‘classical’ computers

Chinese scientists claim to have built the world’s fastest programmable quantum computers, which appear to crack problems that are currently not feasible for ”classical” non-quantum computers.

The researchers led by Pan Jianwei from the University of Science and Technology of China (USTC), said one of the quantum computing systems — Zuchongzhi 2.1 — is a million times more powerful than its nearest competitor, Google’s Sycamore.

Their programmable superconducting quantum computer, named after a 5th-century mathematician, is 10 million times faster than the world’s fastest supercomputer, the scientists said.

Besides, their photonic quantum computer based on light — Jiuzhang 2 — can carry out calculations 100 trillion times faster than the world’s fastest existing supercomputer, the physicists noted in another study, published in the journal Physical Review Letters on Monday.

In conventional computers, the most basic unit of information is a bit, and data is fundamentally stored in binary codes of 1s and 0s. On the other hand, quantum computers make use of the special properties of the smallest particles in the universe which can exist in multiple states — as zeros and ones at the same time, or in any position between.

This flexibility of quantum particles allows for quantum bits, or qubits, using which many different calculations can be performed simultaneously, scientists said.

The simplest example would be XOR encryption.

This elementary method is unbreakable. Decryption is only possible with the key. There is no way to generate the key if all you have is the encrypted data.

The method has drawbacks, the key length is equal to the length of the encrypted data. This is mitigated by the existence of cheap and large uSD cards.

Like all secret-key methods you are hampered by the key-exchange problem.

With XOR encryption all possible keys for a given file are equally valid thus there is no way to decide which decryption is the intended one...

The XOR method depends upon the ability to create quantum random numbers... this is easy now but was once difficult. The German Enigma machine was an XOR device that depended on a mechanical means to generate random numbers...the problem is that no mechanical method can produce true random numbers and no software can either. It requires a quantum event like diode noise, Brownian motion or radioactive decay..etc

At this time there is no public-key encryption method that can be said to be forever secure. This is a pity as public-key is so handy.

XOR encryption is totally secure so long as the key is at least equal in length to the data to be secured and the key is made up of truly random numbers. When these conditions are met you have what is known as a one-time-pad which has long been deemed unbreakable. You must also never encrypt more than one file using the same key.

IMO, it will be a nearly impossible task for quantum computers to break a well-designed symmetric algorithm such as AES. The best known attacks against modern symmetric methods can at best only weaken the methods slightly... good keys of sufficient length will become more and more important as time marches on...

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