Quantum computers are surprisingly random – but that’s a good thing

Quantum computers can produce a randomness much more easily than we thought before, a surprising discovery that shows that we still have a lot to learn about how the strange kingdom of quantum physics believes itself with calculation.

The random is a key component of many calculation tasks – weather forecasts, for example, imply the simulation of atmospheric behavior several times, each time with a slightly different initial configuration chosen at random. For quantum computers, organizing their quantum or quit bits, in random configurations to produce results is a way in which researchers have tried to demonstrate the quantum advantage, where quantum computers can perform tasks that are effectively impossible for conventional machines.

The configuration of these random configurations essentially means the mixture of qubits and how they connect several times, similar to the way you mix a card set. But just like a larger card office is heavier than the smaller one, this process was considered much more time by adding more qubits to your system. Since more mixtures increase the chances of ruining the delicate quantum state of qubits, this meant that many useful applications that were based on chance were considered to be limited to small quantum computers.

Now Thomas Schuster at the California Institute for Technology and his colleagues have discovered that these random sequences can be produced with fewer shuffles than we thought, which opens up the possibility of using Qubit sequences arranged at random that would have been too complex to be implemented on larger quantum computers.

To show it, Schuster and his team imagined dividing a collection of smaller blocks, then proved mathematically that these blocks could each produce a random sequence. Then, they proved that these smaller qubit blocks could be “glued” together, creating a well repressed version of the original whole of qubits in a way that you would not necessarily wait.

“It is simply very surprising, because you can show that similar things do not hold for generators of random numbers in conventional systems,” explains Schuster. For example, the mixture of a game of blocks in blocks would be very visible, because the upper block cards would always remain near the summit. This is not true in the quantum case, because the quantum mixture creates a random overlapping of all possible reshuffles.

“This is a much more complicated object than a classic shuffler. For example, the control of superior cards is no longer fixed, because we are a superposition of many possible reorganizations, so if I try the classic approach above and measure the location of the upper cards after the mixture, explains Schuster. “It’s really a kind of new and intrinsically quantum phenomenon.”

“This type of random quantum behavior, we all expected to be extremely difficult to generate, and here the authors have shown that you could do so essentially as effectively as you can imagine,” explains Pieter Claeys at the Max Planck Institute for complex systems physics in Germany. “It was a very surprising observation.”

“Random quantum circuits have a plethora of uses as ingredients in quantum algorithms, and even for demonstrating so-called quantum supremacy,” said Ashley Montanaro at the University of Bristol, in the United Kingdom. “The authors already identify many applications in quantum information, and I expect others to follow.” For example, this would facilitate the type of experience on the quantum advantage that researchers have done before, although Montanaro provide that this does not in turn mean that the harvesting of the practical advantages of such an advantage is closer.