Frame synchronization method for QKD systems
First Claim
1. A method of managing quantum signal transmission in a quantum key distribution (QKD) system having QKD stations Bob and Alice using frame synchronization, comprising:
- forming a stream of quantum signals at Alice;
sending a first ready signal from Bob to Alice that defines a start of a first frame of multiple frames each consisting of a set of encoded quantum signals;
performing a first encoding of the quantum signals at Alice and transmitting the first-encoded quantum signals to Bob in the first frame;
performing a second encoding of the first-encoded quantum signals at Bob and detecting the twice-encoded quantum signals at Bob for the first frame;
at Alice, terminating the first encoding of the quantum signals at Alice at the end of the first frame while continuing to form quantum signals that are not included in a subsequent frame;
sending a second ready signal from Bob to Alice to initiate at Alice the first-encoding of quantum signals to form the subsequent frame of encoded quantum signals;
synchronizing the sending of frames of encoded quantum signals from Alice to Bob by sending synchronization signals from Alice to Bob; and
performing qubit indexing that assigns a frame number to each frame and a qubit position of each encoded qubit within each frame.
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Abstract
Systems and methods for exchanging and processing encoded quantum signals in quantum key distribution (QKD) systems in real time. A stream of quantum signals is sent from Alice to Bob. Alice only encodes sets or “frames” of the streamed quantum signals based on receiving a “ready” message from Bob. This allows for Bob to finish processing the previous frame of data by allowing different bit buffers to fill and then be used for data processing. This approach results in gaps in between frames wherein quantum signals in the stream are sent unencoded and ignored by Bob. However, those quantum signals that are encoded for the given frame are efficiently processed, which on the whole is better than missing encoded quantum signals because Bob is not ready to receive and process them.
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Citations
10 Claims
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1. A method of managing quantum signal transmission in a quantum key distribution (QKD) system having QKD stations Bob and Alice using frame synchronization, comprising:
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forming a stream of quantum signals at Alice; sending a first ready signal from Bob to Alice that defines a start of a first frame of multiple frames each consisting of a set of encoded quantum signals; performing a first encoding of the quantum signals at Alice and transmitting the first-encoded quantum signals to Bob in the first frame; performing a second encoding of the first-encoded quantum signals at Bob and detecting the twice-encoded quantum signals at Bob for the first frame; at Alice, terminating the first encoding of the quantum signals at Alice at the end of the first frame while continuing to form quantum signals that are not included in a subsequent frame; sending a second ready signal from Bob to Alice to initiate at Alice the first-encoding of quantum signals to form the subsequent frame of encoded quantum signals; synchronizing the sending of frames of encoded quantum signals from Alice to Bob by sending synchronization signals from Alice to Bob; and performing qubit indexing that assigns a frame number to each frame and a qubit position of each encoded qubit within each frame. - View Dependent Claims (4, 5, 6, 7)
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2. A method of transmitting quantum signals between two QKD stations Alice and Bob in a QKD system using frame synchronization to form a quantum key, comprising:
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transmitting frames consisting of encoded quantum signals from Alice to Bob only when Bob sends corresponding “
ready”
signals to Alice, wherein one or more unencoded quantum signals reside between at least one pair of adjacent frames;during said transmitting, processing data from previous frames in raw-bits (RB) buffers, sifted-bits (SB) buffers, and error-corrected-bits (EC) buffers at Alice and Bob, including copying and processing blocks of bits from each buffer in order to continually free up space in the buffers to prevent or reduce any delays in transmitting frames; synchronizing the sending of frames of encoded quantum signals from Alice to Bob by sending synchronization signals from Alice to Bob; performing qubit indexing that assigns a frame number to each frame and a qubit position of each encoded qubit within each frame; and forming a quantum key based on the encoded quantum signals transmitted in the multiple frames. - View Dependent Claims (3)
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8. A method of processing quantum signals sent between first and second quantum key distribution (QKD) stations Alice and Bob, the method comprising:
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a) at Alice;
i) generating a continuous stream of quantum signals and in response to a ready signal from Bob;
ii) initiating encoding of the quantum signals in the continuous stream of quantum signals so as to generate a frame'"'"'s worth of encoded quantum signals; and
ii) passing basis and key bit data for each encoded quantum signal of the first frame to a raw-bits (RB) buffer at Alice as Alice'"'"'s first frame data;b) at Bob;
i) encoding the encoded quantum signals from Alice to form twice-encoded quantum signals;
ii) detecting the twice-encoded quantum signals in the first frame; and
iii) passing detection and encoding basis data for the first frame to a raw-bits (RB) buffer at Bob as Bob'"'"'s first frame data;c) sending subsequent frames of encoded quantum signals from Alice to Bob in response to corresponding subsequent ready signals sent from Bob to Alice, wherein at least one pair of adjacent frames has one or more unencoded quantum signals therebetween; d) synchronizing the sending of frames of encoded quantum signals from Alice to Bob by sending synchronization signals from Alice to Bob; and e) performing qubit indexing that assigns a frame number to each frame and a qubit position of each encoded qubit within each frame. - View Dependent Claims (9, 10)
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Specification