Truly random number generation based on measurement of phase noise of a laser

Abstract

We present a simple approach to realize truly random number generation based on measurement of the phase noise of a single mode vertical cavity surface emitting laser (VCSEL). The true randomness of the quantum phase noise originates from the spontaneous emission of photons and the random bit generation rate is ultimately limited only by the laser linewidth. With the final bit generation rate of 20 Mbit/s, the physically guaranteed truly random bit sequence passes the three standard random tests. Moreover, for the first time, a continuously generated random bit sequence up to 14 Gbit is verified by two additional criteria for its true randomness. [4]. Traditionally, pseudorandom number generator (PRNG) based on computational algorithms is adopted to generate random bits and is competent in many fields. However, it cannot produce truly random (unpredictable and irreproducible) bit sequence, and so may result in potential dangers in security related applications, say, in quantum cryptography [5]. Actually, the unconditional security of quantum key distribution can ONLY be guaranteed when a truly random number generator (TRNG), based on quantum mechanical process instead of the intractability assumption with classical algorithms [6], is available.Distinct from PRNG, a TRNG can only be realized by a physical way, instead of an algorithm-based way; however, a physical way does not sufficiently guarantee the true randomness. The physically random processes, such as radioactive decay [7], electric noise in circuits [8], frequency jitter of electric oscillator [9], and those based on laser (photon) emission/detection [10][11][12], can ensure the inability of pre-estimation on random numbers and so can be adopted as candidates to implement TRNG. In particular, those based on the detection of laser field attracted tremendous interests in recent decade.

Strong experimental guarantees in ultrafast quantum random number generation

“…Nearly all experimental claims of QRNG to date implicitly or explicitly assume nonadversarial devices, with varying degrees of trust in their sources [2,3,[5][6][7][9][10][11][12][22][23][24][25][26][27][28]. To take the best-known example, splitting a single photon on an ideal 50:50 beam splitter gives a random direction to the photon, and this direction can be measured to give one perfectly random bit.…”

“…Processes used have included radioactive decay [1], path-splitting of single photons [2], photon number path entanglement [3], amplified spontaneous emission [4], measurement of the phase noise of a laser [5][6][7][8], photon arrival time [9], vacuum-seeded bistable processes [10], and stimulated Raman scattering [11]. Quantum random number generators (QRNGs) are attractive because their randomness can be linked to well-tested principles of quantum mechanics, e.g., the uncertainty principle [12], which guarantees a minimum amount of randomness in some physical quantities.…”

Maximization of Extractable Randomness in a Quantum Random-Number Generator

“…RNGs that rely on quantum processes (QRNGs), on the other hand, can have guaranteed indeterminism and entropy, since quantum processes are inherently unpredictable [7,8]. Examples of such processes include quantum phase fluctuations [9][10][11][12][13], spontaneous emission noise [14][15][16], photon arrival times [17][18][19], stimulated Raman scattering [20], photon polarization state [21,22], vacuum fluctuations [23,24], and even mobile phone cameras [25]. These QRNGs resolve both shortcomings of the PRNGs.…”

Frequency noise characteristics of a diode laser and its application to physical random number generation

“…5,6 In this instance, a generation speed of 500 Mb∕s has been reported. There are several other papers describing generators operating at the range of Gbit∕s 7-10 that exploit the chaotic response of a diode laser whose light is reflected directly back to its source.…”