Random number generator

1. A method for generating random numbers including:

mixing a bright quantum state in a first mode with a vacuum input, in a two mode transformation for mixing the first mode with a second mode, orthogonal to the first mode;

after mixing, detecting the number of particles in the first mode, and the second mode;

generating random numbers based on the difference between the number of particles in the first mode and the second mode; and

simultaneously to generating random numbers, certifying the numbers as random, based on the total number of particles in the first mode and the second mode,

wherein certifying confirms that the process by which the random numbers are generated is quantum in origin and so the numbers are random.

2. The method of claim 1 , including generating certified random numbers based on the difference between the number of particles in the first mode and the second mode and the total number of particles in the first mode and the second mode, such that the numbers are certified when they are generated.

3. The method of claim 1 , including:

after mixing, detecting an intensity in the first mode and second mode; and determining the number of particles in the first mode and the second mode, based on the detected intensity.

4. The method of claim 1 , wherein after mixing the bright quantum state in the first mode with the vacuum input, each particle is randomly detected in the first mode or the second mode, such that the difference between the number of particles in the two modes has high entropy.

5. The method of claim 3 , including:

calibrating detectors used to detect the intensity in the first mode and the second mode, such that the number of particles incident on the detector is estimated based on an output signal of the detector,

wherein the detectors are calibrated to underestimate the number of particles.

6. The method of claim 5 , wherein the detector is calibrated with a first source, and the bright quantum state in a first mode is generated by a second source.

7. The method of claim 1 , wherein the numbers are certified as random if the total number of particles in the first mode and second mode is above a minimum threshold.

8. The method of claim 1 , including:

for a plurality of measurements, grouping the results based on the total number of particles in the first mode and the second mode; and

for each measurement, generating random numbers based on the difference between the number of particles in the first mode and the second mode recorded for measurements with the same total number of particles.

9. The method of claim 1 , wherein the bright quantum state comprises photons collected from an incident light source.

10. The method of claim 1 , wherein the modes are selected from at least: optical polarisation modes; spatial modes; temporal modes; and spectral modes.

11. The method of claim 1 , including:

generating the bright quantum state, such that the state is pulsed; and

detecting the number of particles in the first mode and second mode for each pulse.

12. A random number generator including:

a mode mixer to mix a first mode of a quantum state with a second mode, orthogonal to the first mode, in a two mode transformation;

a source for providing a bright quantum state in the first mode to the mode mixer;

a vacuum input to the mode mixer, such that the first mode is mixed with the vacuum input;

a detector arranged to detect the number of particles in the first mode and the second mode after mixing; and

a controller arranged to:

generate random numbers based on the difference between the number of particles in the first mode and the second mode; and

certify that the process by which the random numbers are generated is quantum in origin, and so the generated numbers are random, based on the total number of particles in the first mode and the second mode,

wherein the random number generator is arranged to generate random number and certification that the numbers are random at the same time.

13. The random number generator of claim 12 , wherein the controller is arranged to generate certified random numbers based on the difference between the number of particles in the first mode and the second mode and the total number of particles in the first mode and the second mode, such that the numbers are certified when they are generated.

14. The random number generator of claim 12 , wherein the detector includes:

a first detector for detecting the first mode; and

a second detector for detecting the second mode.

15. The random number generator of claim 12 , wherein the controller includes:

a binning module to group separate measurements, based on the total number of particles in the first mode and the second mode, wherein

the controller is arranged to generate random numbers based on the difference between the number of particles in the first mode and the second mode recorded for measurements with the same total number of particles in the first mode and the second mode.

16. The random number generator of claim 12 , wherein the source is pulsed, and wherein random numbers are generated from each pulse.

17. The random number generator of claim 12 , wherein the modes are selected from at least: optical polarisation modes; spatial modes; temporal modes; and spectral modes.

18. The random number generator of claim 12 , wherein the mode mixer is a 50:50 mode mixer.

19. The random number generator of claim 18 , wherein the mode mixer comprises:

a half wavelength waveplate; and

a polarising beam splitter.

20. The random number generator of claim 12 , wherein the mode mixer is coupled to the source and the detector by optical fibres.