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Simple and reliable method for preparing any Werner state

A reliable and simple technology, applied in the field of quantum information processing and quantum information, can solve the problems of complex adjustment and difficult operation, and achieve the effects of high integration, expansion and convenient adjustment

Active Publication Date: 2018-01-19
NANJING UNIV OF POSTS & TELECOMM
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Problems solved by technology

[0008] The technical problem to be solved by the present invention is that the existing method for preparing two-photon Werner states can only prepare two-photon Werner states with specific parameters, and the problem that the adjustment is relatively complicated and the operation is difficult

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  • Simple and reliable method for preparing any Werner state
  • Simple and reliable method for preparing any Werner state
  • Simple and reliable method for preparing any Werner state

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Embodiment Construction

[0024] The present invention adds a depolarization channel on the basis of the above-mentioned sandwich-type entangled photon source, and designs a completely dephased channel. The fully dephasing channel of the present invention includes YVO 4 Crystal, LiNbO 3 crystal, and a half-wave plate placed between two of the above crystals. The YVO 4 The cut angle of the crystal is 0 degrees, LiNbO 3 The cutting angle of the crystal is 45 degrees. It is required that the pump laser is normally incident on the crystal. The optical axes of the two dephasing crystals are parallel and form an angle of 22.5 degrees with the fast axis of the half-wave plate.

[0025] In a fully dephased channel, YVO 4 Crystal, LiNbO 3 The role of the crystal and the half-wave plate is to separate the polarized wave packets in space and time. When the entangled state passes through the channel, dephasing will occur, making the entangled state into a completely mixed state. Wherein, the operating wavel...

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Abstract

The invention discloses a simple and reliable method for preparing any Werner state, comprising a step of preparing an entanglement light source, in which photon pairs are entangled by using laser topump nonlinear crystals to generate a spontaneous parametric down conversion process, and a step of constructing a controllable depolarized channel, in which a completely mixed state is introduced byacting the controllable depolarized channel on one photon. Sandwich-shaped crystals are adopted for the nonlinear crystals and comprise two BBO crystals and a real zero-order half-wave plate disposedbetween the two BBO crystals. The controllable depolarized channel is composed of a Sagnac ring, a complete destructive phase channel and a state superposition portion, the Sagnac ring is of a rectangular structure, and a half-wave plate is disposed between two reflectors thereof; the complete destructive phase channel is composed of two destructive phase crystals and a half-wave plate therebetween; and the state superposition portion comprises a BS. The simple and reliable method is convenient to adjust and high in feasibility, and can be applied to the fields of quantum information processing and quantum communication.

Description

technical field [0001] The invention belongs to the technical field of quantum information, and specifically relates to the preparation of a quantum entanglement light source, which can be applied in the fields of quantum information processing and the like. Background technique [0002] Entanglement is one of the most important properties of the quantum world and the core resource of quantum information technology. As a resource, entanglement can accomplish some tasks that cannot be accomplished by classical resources, such as quantum teleportation, quantum dense coding, etc. In quantum information, the storage, representation and extraction of information are inseparable from quantum states and their evolution process, and entangled states are a particularly important class of quantum states. In real life, the quantum system will inevitably interact with the external environment, resulting in decoherence, which makes the pure quantum state depolarized into a mixture of en...

Claims

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Application Information

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IPC IPC(8): G02F1/35G02F1/355G02B27/28
Inventor 王琴王涔洋刘童俊李剑
Owner NANJING UNIV OF POSTS & TELECOMM
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