Quantum computers could one day threaten the safety of the internet by breaking encryption 鈥� and now they are a step closer.
A quantum computing start-up company called Zapata has worked with IBM to develop a new way to factor large numbers, using it on the largest number that has been factored with a quantum computer so far. The team found that 1,099,551,473,989 is equal to 1,048,589 multiplied by 1,048,601.
The future success of the algorithm used could have big implications for cryptography, because many encryption techniques rely on the fact that it is difficult to split a number into its prime factors.
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Anthony Annunziata at IBM announced this advance at the Q2B conference in California on 11 December. The method used to factor this large number is based on a hybrid quantum-classical computer, and the quantum device used was relatively small at just eight qubits, or quantum bits.
鈥淚t鈥檚 sort of like solving a sudoku 鈥� you鈥檙e filling in the numbers that you need to multiply together, but some of the numbers are lower-hanging fruits than others,鈥� says Yudong Cao at Zapata. 鈥淭he idea is to use the classical computer to fill in the ones that are easier and relatively obvious.鈥� Then the quantum computer comes in and finds the more difficult components, which could take a classical computer a prohibitively long time to figure out.
This number is still much smaller than the largest number a classical computer has ever factored, which has more than 350 digits, but this method may be able to surpass classical computers within the next decade, says Cao. The , also set by IBM, was factoring 4,088,459.
That could one day be a problem because many types of data encryption are based on factoring large numbers, If anyone can do this easily with the help of a quantum computer, it may render some forms of encryption useless 鈥� although plans for post-quantum cryptography are already in the works. Cao says that it could also be an issue for some protocols used in the blockchains used for cryptocurrency.
鈥淚t behoves us to start thinking about this, because on a relatively small device quantum-wise, we鈥檝e been able to do a very large number,鈥� says Zapata CEO Christopher Savoie. He warns that quantum computers may be able to break encryption sooner than we thought using methods like this.
