# US 11,442,698 B2 · Quantum random number generators

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- Number: US 11,442,698 B2
- Document ID: US11442698B2
- Status: Granted
- Kind: B2
- Application number: 16/748,159
- Filed: 2020-01-21
- Published: 2020-07-23
- Granted: 2022-09-13
- Earliest claimed: 2011-09-30
- Assignees: Triad National Security, LLC
- Applicants: Triad National Security, LLC
- Inventors: Jane Elizabeth Nordholt; Richard John Hughes; Raymond Thorson Newell; Charles Glen Peterson
- Web page: https://patentgrep.com/patent/US11442698B2

## CPC

- G06F 7/588: {Random number generators, i.e. based on natural stochastic processes}
- H04L 9/0852: {Quantum cryptography (transmission systems employing electromagnetic waves other than radio waves, e.g. light, infrared H04B10/00; wavelength-division multiplex systems H04J14/02; WDM arrangements H04J14/03)}
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

Random number generators include a thermal optical source and detector configured to produce random numbers based on quantum-optical intensity fluctuations. An optical flux is detected, and signals proportional to optical intensity and a delayed optical intensity are combined. The combined signals can be electrical signals or optical signals, and the optical source is selected so as to have low coherence over a predetermined range of delay times. Balanced optical detectors can be used to reduce common mode noise, and in some examples, the optical flux is directed to only one of a pair of balanced detectors.

## Claims

### Claim 1

A method for processing a digitized output, comprising:
receiving, from an analog-to-digital converter (ADC), a first bit stream generated based at least in part on random fluctuations of a thermal light source;
applying a stream algorithm to the first bit stream to generate a second bit stream of independent, unbiased random bits; and
applying a random extractor function to the second bit stream to generate a third bit stream corresponding to a shorter bit stream than the second bit stream, the third bit stream having one bit of quantum minimum entropy per bit.

### Claim 2 (depends on 1)

The method of claim 1, wherein the first bit stream comprises eight-bit words.

### Claim 3 (depends on 1)

The method of claim 1, further comprising inputting the third bit stream to a cryptographic deterministic random bit generator (DRBG) to generate a fourth bit stream.