Apparatus and method for generating at least one random number, use of an optical parametric oscillator

1. An apparatus for generating at least one random number, comprising:

an optical parametric oscillator being pumped by a pump signal with a predetermined pump power and a predetermined pump frequency, the optical parametric oscillator being configured to operate in a period multiplication state for providing an oscillator output signal of light pulses with alternating pulse energy, the oscillator output signal having a period that is N-times the period of the pump signal, where N is an integer and N>1;

a comparing unit being configured to compare the output signal with a reference signal, wherein the reference signal has a frequency that is 1/N of the predetermined pump frequency; and

an evaluation unit being configured to generate the at least one random number based on the comparison of the output signal with the reference signal.

2. The apparatus according to claim 1 , wherein

the comparing unit comprises a phase determination unit being configured to determine a phase (φ) of the oscillator output signal with respect to the reference signal, and

the evaluation unit is configured to generate the at least one random number based on the determined phase (φ).

3. The apparatus according to claim 2 , wherein the evaluation unit is preferably configured to generate a 0-bit or a 1-bit depending on whether the determined phase (φ) is below or above a threshold value.

4. The apparatus according to claim 1 , wherein the oscillator output signal is a pulse train of alternating high (H) and low (L) pulses, and wherein the evaluation unit is configured to generate a 1-bit or a 0-bit depending on whether the high (H) pulses or the low (L) pulses of the oscillator output signal are synchronous with pulses of the reference signal.

5. The apparatus according to claim 1 , further comprising a switching unit configured to switch on and off the optical parametric oscillator, wherein the switching unit is in a resonator of the optical parametric oscillator, and/or wherein the switching unit is configured to inhibit a light pulse oscillation within the resonator of the optical parametric oscillator.

6. The apparatus according to claim 5 , further comprising a trigger unit for providing a trigger signal, wherein the comparing unit is configured to compare the oscillator output signal with the reference signal in response to the trigger signal.

7. The apparatus according to claim 6 , wherein the trigger unit is configured to provide an on-state trigger signal during an on-state of the optical parametric oscillator, wherein the on-state of the optical parametric oscillator relates to the period multiplication state of the optical parametric oscillator.

8. The apparatus according to claim 6 , wherein the trigger unit is configured to provide an off-state trigger signal during an off-state of the optical parametric oscillator.

9. The apparatus according to claim 6 , wherein the trigger unit is coupled to the switching unit.

10. The apparatus according to claim 5 , wherein the switching unit is an optical switching unit.

11. The apparatus according to claim 1 , wherein the apparatus further comprises a reference signal generator configured to provide the reference signal.

12. The apparatus according to claim 11 , wherein the reference signal is based on the pump signal.

13. The apparatus according to claim 11 , wherein the apparatus is configured such that a plurality of random numbers can be generated simultaneously by using a temporal multiplexing and/or a spectral multiplexing.

14. A method for generating at least one random number, comprising the steps of:

providing an optical parametric oscillator being pumped by a pump signal with a predetermined pump power and a predetermined pump frequency, the optical parametric oscillator being configured to operate in a period multiplication state for providing an oscillator output signal of light pulses with alternating pulse energy, the oscillator output signal having a period that is N-times the period of the pump signal, where N is an integer and N>1;

operating the optical parametric oscillator in the period multiplication state;

comparing the oscillator output signal with a reference signal, wherein the reference signal has a frequency that is 1/N of the predetermined pump frequency; and

generating the at least one random number based on the comparison of the oscillator output signal with the reference signal.

15. The method according to claim 14 , wherein the step of comparing the oscillator output signal with the reference signal comprises determining a phase (φ) of the oscillator output signal with respect to the reference signal, wherein the at least one random number is generated based on the determined phase (φ), and wherein generating the at least one random number preferably comprises generating a 0-bit or a 1-bit depending on whether the determined phase (φ) is below or above a threshold value.

16. The method according to claim 14 , wherein the oscillator output signal is a pulse train of alternating high (H) and low (L) pulses, and wherein generating the at least one random number comprises generating a 1-bit or a 0-bit depending on whether the high (H) pulses or the low (L) pulses of the oscillator output signal are synchronous with pulses of the reference signal.

17. The method according to claim 14 , further comprising the step of:

switching on the optical parametric oscillator and performing at least one toss measurement by comparing the oscillator output signal with the reference signal upon having switched on the optical parametric oscillator.

18. The method according to claim 14 , further comprising the step of:

switching off the optical parametric oscillator and performing at least one control measurement by comparing the oscillator output signal with the reference signal upon having switched off the optical parametric oscillator.

19. The method according to claim 14 , further comprising the steps of:

switching on and off the optical parametric oscillator for a predetermined number of times;

performing a corresponding number of toss measurements by comparing the oscillator output signal with the reference signal upon each switching-on step; and

generating a corresponding number of random numbers based on the comparisons of the oscillator output signal with the reference signal.

20. A method for generating at least one random number, the method comprising:

operating an optical parametric oscillator in a period multiplication state for providing an oscillator output signal of light pulses with alternating pulse energy; and

generating the at least one random number based on the oscillator output signal.