• ABSTRACT – HUMAN RANDOMNESS TO GENERATE QUANTUM RANDOM NUMBERS

It has been shown in theory that Bell inequality violations can be used to generate perfectly random bits with very strong guarantees, stronger than any other known method to make random bits. But a Bell test itself requires random bits as input, to choose the basis settings. This seems to create a “boostrapping problem”, in which guaranteed randomness is required in order to produce guaranteed randomness. Human randomness may provide a solution. Because people have free will they are unpredictable, but we also know that they are not perfectly random; there are always some patterns in the things they choose to do. In our experiment we will use a different Bell inequality (not the usual CHSH inequality), one that has only a mild randomness requirement. We will then experimentally verify if there is a violation using randomness from human choices (free will). This will help us to test our Bell inequality and to close the randomness loophole with the help of human free will.

• FACTS
  • The diameter of the single photon superconduct nano wire detector is only tens of microns, which is much smaller than the diameter of a hair!
  • The frequency of generated entanglement photon pairs, although invisible, is very suitable for transmitting in optical fibers.
  • Do you know that to cool down to a very low temperature, you need to pump the chamber to vacuum first.
  • The entanglement pair generation is a kind of “nonlinear optics”, one pair of entanglement is generated with more than 1 000 000 000 pump photons hit the crystal.

1. Name of lab:

Division of Quantum Physics and Quantum Information, Hefei National Laboratory for Physical Sciences at Microsale, USTC

2. Team:

Yang Liu, Xiao Yuan, Jian-Yu Guan, Jiaqiang Zhong, Ming-Han Li, Cheng Wu, Lixing You, Zhen Wang, Xiongfeng Ma, Qiang Zhang (PI) and Jian-Wei Pan (PI).

3. Organization:

CAS – Center for excellence and Synergetic Innovation Center of Quantum Information and Quantum Physics. USTC – University of Science and Technology of China

4. City:

Shanghai

5. GPS coordinates of the experiment:

31°07″26.9″N 121°32″48.9″E

6. Name of the experiment:

Bell tests with imperfect human input randomness

7. Target Bell inequality and experimental result obtained:

The test indicates how unpredictable the Bellsters must be to disprove local realism.  With CHSH, we observed S = 2.804, which disproves local realism unless the entangled particles can predict Alice and Bob’s choices at least 85 % of the time.With the PRBLG inequality, which is designed for this kind of test, we saw J_{1/4} = 0.0181 \pm 0.0006, which disproves local realism unless the particles can predict Alice and Bob’s choices at least 90 % of the time.

7. What did the experiment test?

The test indicates how unpredictable the Bellsters must be to disprove local realism.  With CHSH, we observed S = 2.804, which disproves local realism unless the entangled particles can predict Alice and Bob’s choices at least 85 % of the time.With the PRBLG inequality, which is designed for this kind of test, we saw J_{1/4} = 0.0181±0.0006, which disproves local realism unless the particles can predict Alice and Bob’s choices at least 90 % of the time.

9. Physical system:

Photons.

10. Degree of freedom measured:

Polarization.

11. Rate of bits consumed & total number of bits:

Estimated rate: 1kbps (kilobit per sencond). Total number of bits: ~80M bits.

12. What was the use of the bits of the Bellsters?

The bits were used to choose the measurement settings, i.e., the basis for each test.

13. How long did the experiment took?

The experiment took two days, from November 30 to December 1.

14. Did you use all the bits in real time?

Yes, we use all the bits in real time. The bits are directly converted into electronical signals to control the basis at the time they arrived.

15. Distance between Alice and Bob:

We have a source and two detection stations. The source is in the middle, and the two detection stations are at the different side of the source. The 3 labs are in a line (Alice’s detection – Source – Bob’s detection). The direct distance between Alice/Bob and source is about 90 meter, with a fibre distance of around 130 meter.Source – Alice’s Detector: 87 m (direct distance)Source – Bob’s Detector: 88 m (direct distance)