A New Photonic Approach to Randomness Manipulation in Quantum Computers
Nature Photonics

Generating random sequences of numbers is essential in many different applications, ranging from computer simulations to cryptographic communications. The so-called "Bernoulli factory" is a notable model that enables to transform the properties of a random sequence in order to fit the specific application.
The intrinsic indetermination of quantum mechanics is believed to be the key for generating genuine random numbers, and recent theoretical works have proposed how to extend the "Bernoulli factory" also to the quantum realm fo “qubits”.
A team of researchers from different institutions, including Politecnico di Milano, IFN-CNR, Sapienza University in Rome and the International Iberian Nanotechnology Labs (INL), has now developed new configurations for manipulating random variables in photonic quantum computers. The results were recently published in Nature Photonics.
The authors implemented the "factory of randomness" in an integrated optical processor. By properly programming the processor and injecting single photons in it, it is possible to evolve the dynamics of the photons, and the quantum information states they carry, in the desired way. Given the statistical behavior that characterizes such photon states, one can generate randomly distributed results more effectively than what can be done by a classical computer.
F. Hoch, et al., “Modular quantum-to-quantum Bernoulli factory in an integrated photonic processor” Nature Photonics (2024).