Hyper-entangled photon server system and associated methods

Patent metadata

Field	Value
Publication number	US-10439737-B2
Application number	US-201815895545-A
Country	US
Kind code	B2
Filing date	Feb 13, 2018
Priority date	Feb 22, 2017
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

A hyper-entanglement photon server (i.e., hub) employs non-degenerate frequencies input as entangled photon pairs into a beam splitter. The beam splitter splits probability amplitudes into two sets of bunched superposition states plus two sets of anti-bunched superposition states. The amplitudes pass through identical Lyot filters and then either enter a polarization beam splitter, where the bunched and anti-bunched states switch identities, or merely advance unchanged to awaiting users at two distinct and spatially-displaced positions (i.e., spokes). The Lyot filters change the output amplitudes from rotationally invariant superpositions of generalized Bell States to rotationally non-invariant superpositions of generalized Bell states. All hubs and spokes pre-share operating key material (a security method called KCQ) that may be continually updated by shared stream ciphers seeded by fresh key material engendered by hub-to-spoke quantum communication.

First claim

That which is claimed is:

1. A method for creating measurements of photons at distinct locations, comprising:
receiving, using a non-polarizing beam splitter (BS), electromagnetic (EM) radiation comprising a hyperentangled photon pair, defined as a first photon and a second photon entangled in a plurality of degrees of freedom including polarization, frequency, and path, wherein frequency is non-degenerate;
spatially separating, using the BS, output probability amplitudes for the non-degenerate frequencies of the hyperentangled photon pair into a first set of anti-bunched rotationally invariant amplitude states and a second set of bunched rotationally invariant amplitude states,
rotating, using a first Lyot filter, the respective polarization of incongruent frequency states in the first set of anti-bunched rotationally invariant amplitude states, to define a first set of anti-bunched non-rotationally invariant amplitude states;
preserving, using the first Lyot filter, the respective polarization of congruent frequency states in the first set of anti-bunched rotationally invariant amplitude states, to further define the first set of anti-bunched non-rotationally invariant amplitude states;
spatially separating, using a first dichroic mirror (DM), the first set of anti-bunched non-rotationally invariant amplitude states by the non-degenerate frequencies of the hyperentangled photon pair, to define a first linear polarized wave and a second linear polarized wave;
passing in line, using a first polarizing beam splitter (PBS), a first subset of photons from the first linear polarized wave, each having a polarization aligned with the first PBS;
reflecting orthogonally, using the first PBS, a second subset of photons from the first linear polarized wave, each having a polarization unaligned with the first PBS; and
measuring, using a first polarization analyzer, the respective polarization of at least one of the first subset of photons and the second subset of photons.

2. The method according to claim 1 wherein rotating the polarizations comprises rotating, using the first Lyot filter, the respective polarization of the incongruent frequency states in the first set of anti-bunched rotationally invariant amplitude states by 90 degrees.

3. The method according to claim 1 wherein measuring the polarizations comprises determining a first photon correlation state, defined as one of 100% correlation and 100% anti-correlation between the respective polarizations of the first subset of photons and the second set of photons.

4. The method according to claim 1 further comprising:
passing in line, using a second polarizing beam splitter (PBS), a third subset of photons from the second linear polarized wave, each having a polarization aligned with the second PBS;
reflecting orthogonally, using the second PBS, a fourth subset of photons from the second linear polarized wave, each having a polarization unaligned with the second PBS; and
measuring, using a second polarization analyzer, the respective polarization of at least one of the third subset of photons and the fourth subset of photons.

5. The method according to claim 1 further comprising:
rotating, using a second Lyot filter, the respective polarization of congruent frequency states in the second set of bunched rotationally invariant amplitude states, to define a second set of bunched non-rotationally invariant amplitude states;
preserving, using the second Lyot filter, the respective polarization of congruent frequency states in the second set of bunched rotationally invariant amplitude states, to further define the second set of bunched non-rotationally invariant amplitude states;
spatially separating, using a second dichroic mirror (DM), the second set of bunched non-rotationally invariant amplitude states by the non-degenerate frequencies of the hyperentangled photon pair, to define a third linear polarized wave and a fourth linear polarized wave;
passing in line, using a third polarizing beam splitter (PBS), a fifth subset of photons from the third linear polarized wave, each having a polarization aligned with the third PBS;
reflecting orthogonally, using the third PBS, a sixth subset of photons from the third linear polarized wave, each having a polarization unaligned with the third PBS; and
measuring, using a third polarization analyzer, the respective polarization of at least one of the fifth subset of photons and the sixth subset of photons.

6. The method according to claim 5 further comprising:
passing in line, using a fourth polarizing beam splitter (PBS), a seventh subset of photons from the fourth linear polarized wave, each having a polarization aligned with the fourth PBS;
reflecting orthogonally, using the fourth PBS, an eighth subset of photons from the fourth linear polarized wave, each having a polarization unaligned with the fourth PBS; and
measuring, using a fourth polarization analyzer, the respective polarization of at least one of the seventh subset of photons and the eighth subset of photons.

7. A linear optical quantum computing (LOQC) system comprising:
a hub server comprising:
a non-polarizing beam splitter (BS) configured to:
receive electromagnetic (EM) radiation comprising a hyperentangled photon pair, defined as a first photon and a second photon entangled in a plurality of degrees of freedom including polarization, frequency, and path, wherein frequency is non-degenerate; and
spatially separate output probability amplitudes for the non-degenerate frequencies of the hyperentangled photon pair into a first set of anti-bunched rotationally invariant amplitude states and a second set of bunched rotationally invariant amplitude states;

a first Lyot filter configured to rotate the respective polarization of incongruent frequency states in the first set of anti-bunched rotationally invariant amplitude states and preserve the respective polarization of congruent frequency states in the first set of anti-bunched rotationally invariant amplitude states, to define a first set of anti-bunched non-rotationally invariant amplitude states; and

at least one spoke client comprising:
a dichroic mirror configured to spatially separate the first set of anti-bunched non-rotationally invariant amplitude states by the non-degenerate frequencies of the hyperentangled photon pair, to define a first linear polarized wave and a second linear polarized wave;
a polarizing beam splitter (PBS) configured to:
pass in line a first subset of photons from the first linear polarized wave, each having a polarization aligned with the PBS; and
reflect orthogonally a second subset of photons from the first linear polarized wave, each having a polarization unaligned with the PBS; and

a polarization analyzer configured to measure the respective polarization of at least one of the first subset of photons and the second subset of photons.

8. The LOQC system according to claim 7 wherein the first Lyot filter is configured to rotate the respective polarization of the incongruent frequency states in the first set of anti-bunched rotationally invariant amplitude states by 90 degrees.

9. The LOQC system according to claim 7 wherein the respective polarization analyzer of the at least one spoke client is configured to determine a first photon correlation state, defined as one of 100% correlation and 100% anti-correlation between the respective polarizations of the first subset of photons and the second set of photons.

10. The LOQC system according to claim 7 wherein the hub server further comprises a second Lyot filter configured to:
rotate the respective polarization of congruent frequency states in the second set of bunched rotationally invariant ampl

Assignees

• Us Gov Air Force
• Us Air Force

Inventors

• Hughes David H
• Erdmann Reinhard K

Classifications

• G02B27/283

  used for beam splitting or combining · CPC title

• G09C1/00

  Apparatus or methods whereby a given sequence of signs, e.g. an intelligible text, is transformed into an unintelligible sequence of signs by transposing the signs or groups of signs or by replacing them by others according to a predetermined system (cryptographic typewriters G09C3/00) · CPC title

• H04B10/70

  Photonic quantum communication · CPC title

• G02B27/288

  Filters employing polarising elements, e.g. Lyot or Solc filters (G02B5/3016 takes precedence) · CPC title

• H04L9/0855

  involving additional nodes, e.g. quantum relays, repeaters, intermediate nodes or remote nodes · CPC title