Practical quantum random number generator based on sampling vacuum fluctuations.

Quantum random number generation is an enabling technology for applications of quantum information science. For instance, a secure quantum key distribution (QKD) system requires a practical, easily integratable, high-quality and fast random number generator. Here, we propose and demonstrate an approach to random number generation that promises to satisfy these requirements. In our scheme, vacuum fluctuations of the electromagnetic-field inside a laser cavity are sampled in a discrete manner in time and amplified by injecting current pulses into the laser. This results in the generation of laser pulses with random phases. Random numbers can be obtained by interfering the laser pulses with another independent laser operating at the same frequency. Using only off-the-shelf opto-electronic and fiber-optic components at 1.5 $\mu$m wavelength, we demonstrate experimentally the generation of high-quality random bits at a rate of up to 1.5 GHz. With the help of better opto-electronic devices, the generation rate of our scheme can be improved up to tens of GHz. Our results show the potential of the new scheme for practical quantum information applications.