Abstract

Random number generators (RNGs) have become a vital ingredient for various applications. Especially in the field of quantum cryptography random numbers are essential for an unconditional secure key distribution [1]. Recently generators based on the foundational unpredictability of quantum mechanics have become increasingly popular to produce truly random numbers [2]. Here, we present a generator producing unique and truly random bit sequences based on the measurement of the quantum uncertainty of a continuous variable vacuum state [3]. Vacuum states have the advantage of being inherently pure states, i.e. they cannot be tempered with by an adversary and are easily detectable. Therefore, they are an ideal resource for a quantum RNG. Our RNG consists of a simple homodyne detection system. A weak signal, which in our case is the vacuum state, and a strong laser beam interfere on a symmetric beamsplitter and its two output beams impinge on two balanced detectors. The signal of the two detectors are digitized, subtracted and stored. By subtracting the two currents, a quadrature amplitude of a pure vacuum state is measured.

© 2011 IEEE