Free-space quantum cryptography system
First Claim
1. A system for quantum key delivery in a single-photon, free-space cryptography scheme comprising:
- a transmitter comprising two pairs of photon sources, each said photon source representing a specific photon polarization direction, a first said pair of photon sources representing a first polarization basis and a remaining said pair of photon sources representing a second polarization basis, said first polarization basis and said second polarization basis prepared as conjugate bases by one of being rotated with respect to each other and disposition of at least one retardation plate in a transmitter path of a photon emitted by at least one of said photon sources resulting in non-orthogonal polarization eigenstates, a transmitter polarizing beamsplitter corresponding to each said pair of photon sources whereby the polarizations of each said photon source of each said pair of photon sources are recombined, a transmitter non-polarizing beamsplitter whereby said recombined polarizations are combined for output to a receiver, and a photon output; and
a receiver comprising a photon input, a receiver non-polarizing beamsplitter whereby said output from said transmitter is separated resulting in a random polarization basis selection, two pairs of photon receivers and a receiver polarizing beamsplitter corresponding to each said pair of photon receivers, said photon receivers and said receiver polarizing beamsplitters disposed inversely with respect to said photon sources and said receiver polarizing beamsplitters having been prepared as conjugate bases by one of being rotated with respect to each other and disposition of at least one retardation plate in a receiver path of a photon received by at least one of said photon receivers, said receiver in communication with said transmitter through a free-space channel.
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Abstract
A system and method for quantum key delivery in a single-photon, free-space cryptography scheme including a transmitter and a receiver. The transmitter includes two pairs of photon sources, each of which represents a specific photon polarization direction. The first pair of photon sources represents a first polarization basis while the remaining pair of photon sources represents a second polarization basis. The first and second polarization basis are rotated with respect to each other so as to produce non-orthogonal polarization eigenstates. A transmitter polarizing beamsplitter corresponding to each of the pairs of the photon sources is provided whereby the polarizations of each of the photon sources of each pair of photon sources are recombined. A transmitter non-polarizing beamsplitter is provided whereby the recombined polarizations are combined for output to the receiver. The receiver includes a set of optics inversely disposed with respect to the optics of the transmitter and two pairs of photon detectors.
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Citations
17 Claims
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1. A system for quantum key delivery in a single-photon, free-space cryptography scheme comprising:
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a transmitter comprising two pairs of photon sources, each said photon source representing a specific photon polarization direction, a first said pair of photon sources representing a first polarization basis and a remaining said pair of photon sources representing a second polarization basis, said first polarization basis and said second polarization basis prepared as conjugate bases by one of being rotated with respect to each other and disposition of at least one retardation plate in a transmitter path of a photon emitted by at least one of said photon sources resulting in non-orthogonal polarization eigenstates, a transmitter polarizing beamsplitter corresponding to each said pair of photon sources whereby the polarizations of each said photon source of each said pair of photon sources are recombined, a transmitter non-polarizing beamsplitter whereby said recombined polarizations are combined for output to a receiver, and a photon output; and
a receiver comprising a photon input, a receiver non-polarizing beamsplitter whereby said output from said transmitter is separated resulting in a random polarization basis selection, two pairs of photon receivers and a receiver polarizing beamsplitter corresponding to each said pair of photon receivers, said photon receivers and said receiver polarizing beamsplitters disposed inversely with respect to said photon sources and said receiver polarizing beamsplitters having been prepared as conjugate bases by one of being rotated with respect to each other and disposition of at least one retardation plate in a receiver path of a photon received by at least one of said photon receivers, said receiver in communication with said transmitter through a free-space channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for quantum key delivery in a single-photon, free-space system comprising the steps of:
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transmitting a photon having a polarization direction corresponding to a bit value from one of two non-orthogonal transmitter polarization basis systems through a transmitter polarizing beamsplitter, from said transmitter polarizing beamsplitter through a transmitter non-polarizing beamsplitter, through a photon output of a transmitter and into a photon input of a receiver; and
passing said photon through a receiver non-polarizing beamsplitter, from said receiver non-polarizing beamsplitter through a receiver polarizing beamsplitter corresponding to one of two non-orthogonal receiver polarization basis systems, and to one of two photon detectors comprising said one of said two non-orthogonal receiver basis systems in said receiver. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification