Quantum entanglement generating system and method, and quantum entanglement generating and detecting system and method

A quantum entanglement generating method comprising:

• producing a light beam of light frequency 2f0 from a laser light source;
• injecting the light beam from the laser light source into a ring interferometer comprising a beam splitter and a plurality of mirrors, the beam splitter and mirrors forming an optical path in the form of a ring;
• splitting the injected light beam at the beam splitter into two light beams traveling mutually contrariwise in direction of advance in the ring interferometer;
• advancing one of the split light beams from an optical parametric amplifier disposed in the optical path of the ring interferometer into a dispersive medium disposed in the optical path of the ring interferometer, to generate a first squeezed light beam of light frequency f0;
• advancing the other of the split light beams from the dispersive medium into the optical parametric amplifier to generate a second squeezed light beam of light frequency f0;
• and
• setting relative phase between the first and second squeezed light beams at a selected value through the dispersive medium, and
• combining the first and second squeezed light beams at the beam splitter, thereby generating quantum entangled beams.

A quantum entanglement generating and detecting system comprising:

• a light source part comprising a pulsed laser light source of light frequency f0 and a second harmonic generator into which the light beam of light frequency f0 is incident to produce a light beam of light frequency 2f0, the light source part emitting a pulsed laser light beam of light frequency f0 and a pulsed laser light beam of light frequency 2f0 on a common axis;
• a ring interferometer comprising a beam splitter and a plurality of mirrors, the beam splitter and mirrors forming an optical path in the form of a ring;
• an optical parametric amplifier inserted in the optical path of the ring interferometer for producing a light beam of light frequency f0 upon receiving a light beam of light frequency 2f0 incident into the optical parametric amplifier;
• a dispersive medium inserted in the optical path of the ring interferometer and
• a homodyne detector,
• wherein the light beam of light frequency 2f0 from the laser light source injects into the beam splitter,
• the beam splitter splits the light beam of light frequency 2f0 into two light beams travelling mutually contrariwise in direction of advance in the ring interferometer, the two light beams injected into the optical parametric amplifier to generate a first and a second linearly polarized, squeezed light beam of light frequency f0 traveling mutually contrariwise in direction of advance in the ring interferometer,
• the dispersive medium adjusts the relative phase between the first and second squeezed light beams at a selected value,
• the beam splitter combines the first and second squeezed light beams to generate a linearly polarized quantum entangled beam of light frequency f0,
• as a signal light beam the linearly polarized quantum entangled beam of light frequency f0, and as a local-oscillator light beam the pulsed laser light beam of light frequency f0 emitted from the light source part and having a polarization orthogonal to the signal light beam, are both incident into the homodyne detector to detect a quadrature amplitude.

A quantum entanglement generating and detecting method comprising:

• producing, on a common optical axis, a light beam of light frequency f0 from a laser light source and a light beam of light frequency 2f0 generated via a second harmonic generator from the laser light source;
• injecting the light beam of light frequency 2f0 from the laser light source into a ring interferometer comprising a beam splitter and a plurality of mirrors, the beam splitter and minors forming an optical path in the form of ring;
• splitting the injected light beam at the beam splitter into two light beams traveling mutually contrariwise in direction of advance in the ring interferometer;
• advancing one of the split light beams from an optical parametric amplifier disposed in the optical path of the ring interferometer into a dispersive medium disposed in the optical path of the ring interferometer, to generate a first linearly polarized, squeezed light beam of light frequency f0;
• advancing the other of the split light beams from the dispersive medium into the optical parametric amplifier to generate a second linearly polarized, squeezed light beam of light frequency f0;
• setting relative phase between the first and second squeezed light beams at a selected value through the dispersive medium;
• and
• combining the first and second squeezed light beams at the beam splitter, thereby generating linearly polarized quantum entangled beams of light frequency f0;
• deriving from the horizontally polarized quantum entangled beams of light frequency f0, a signal light beam for a homodyne detector;
• passing the light beam of light frequency f0 from the laser light source through the ring interferometer via an optical path identical to that for the one split light beam split into by the beam splitter, to provide a light beam of a polarization orthogonal to the signal light beam for use as a local-oscillator light beam for the homodyne detector;
• and
• the homodyne detector detecting a quadrature amplitude of the signal light beam.