Ut-battelle, Inc.

Cisco Technology, Inc.

Bing Qi

Warren P Grice

Philip G Evans

Alireza Shabani

Stephen Magno DiAdamo

Raphael C Pooser

Benjamin J Lawrie

Brian P Williams

Glen W Miller

Ramana Rao Venkata Renuka Kompella

Reem M Mandil

An endpoint receives a photon signal jointly encoded in time and frequency as a time-frequency state, and separates the photon signal with a dispersive element to generate frequency components. The endpoint delays each corresponding frequency component by a corresponding time delay to separate out the frequency components in time before the endpoint recombines the frequency components to generate a frequency-separated signal. The endpoint measures the frequency-separated signal to determine the time-frequency state of the photon signal.

Joint time-frequency measurement in optical communication

A network element in a quantum network receives a hybrid frame including a classical header and a quantum payload. The network element processes the classical header for a length of time and generates a new classical header. The network element drops a portion of the quantum payload based on the length of time spent processing the classical header and updates the hybrid frame to include the new classical header and the quantum payload without the dropped portion.

Packet-switching quantum key distribution

A network element receives a classical header for a quantum payload, and processes the classical header to determine a destination endpoint for the quantum payload. The network element generates a new classical header for the quantum payload based on the destination endpoint. The network element sends the new classical header to a next hop ahead of the quantum payload at a time based on a number of hops between the network element and the destination endpoint.

Packet switched quantum network

A passive continuous variable quantum key distribution scheme, where Alice splits the output of a thermal source into two beams, measures one locally and transmits the other mode to Bob after applying attenuation. A secure key can be established based on measurements of the two beams without the use of a random number generator or an optical modulator.

Passive continuous variable quantum key distribution scheme using a thermal source

A first endpoint in a Quantum Key Distribution (QKD) system determines an operating mode for a hybrid transceiver for communicating in an optical communication session with a second endpoint. The operating mode is selected from a group containing a classical reception mode, a classical transmission mode, a quantum transmission mode, and a quantum reception mode. The first endpoint configures an input to a homodyne detector of the hybrid transceiver based on the operating mode and operates the hybrid transceiver in the operating mode for at least a portion of the optical communication session.

Hybrid coherent optical transceiver for quantum and classical communication

A system and a receiver for generating quantum key(s) using conjugated homodyne detection is provided. The receiver may communicate with a transmitter via an insecure quantum channel and a classical channel to generate the quantum key(s). A decoder, in the receiver, may determine, based at least in part on quadratures X, P measured by conjugated homodyne detectors, a raw-key signal corresponding to a key signal generated by the transmitter, and a distribution of photon numbers corresponding to a quantum signal received via the insecure quantum channel. Information about the key signal is exchanged between the receiver and the transmitter via the classical channel and used to determine a quantum bit error rate of the determined raw-key signal. A gain is also obtained. A secure-key rate is calculated based at least in part on the gain, the quantum bit error rate, and the photon number distribution.

Discrete variable quantum key distribution using conjugate homodyne detection

Continuous variable quantum secret sharing (CV-QSS) technologies are described that use laser sources and homodyne detectors. Here, a Gaussian-modulated coherent state (GMCS) prepared by one device passes through secure stations of other devices sequentially on its way to a trusted device, and each of the other devices coherently adds a locally prepared, independent GMCS to the group of propagating GMCSs. Finally, the trusted device measures both the amplitude and the phase quadratures of the received group of coherent GMCSs using double homodyne detectors. The trusted device suitably uses the measurement results to establish a secure key for encoding secret messages to be broadcast to the other devices. The devices cooperatively estimate, based on signals corresponding to their respective Gaussian modulations, the trusted device's secure key, so that the cooperative devices can decode the broadcast secret messages with the secure key.

Continuous variable quantum secret sharing

A passive continuous-variable quantum key distribution scheme, where Alice splits the output of a thermal source into two spatial modes, measures one locally and transmits the other mode to Bob after applying attenuation. A secure key can be established based on measurements of the two modes without the use of a random number generator or an optical modulator.

Quantum key distribution using a thermal source

An improved coherent communication scheme is provided. The coherent communication scheme encodes both classical and quantum information simultaneously using isolated groups of states: classical information is represented by different groups and can be decoded deterministically; and quantum information is represented by highly overlapped states within the same group, thus guaranteeing security. Decoding includes projecting the detection results at the receiver to one of the distinguishable encoding groups first, which allows the classical information to be read out, and then generating a quantum key from the residual randomness. This communications scheme enables simultaneous classical communication and QKD over the same communication channel using the same transmitter and receiver, opening the door to operate QKD in the background of classical communication and at negligible costs.

Simultaneous classical and quantum communication scheme based on coherent detection

A system and method are provided to yield a QRNG based on homodyne detection of quantum noise (e.g., vacuum noise measured as shot noise) generated from a local oscillator, such as an LED. In one embodiment, a QRNG may be provided that is adjustable based on a control input to produce a random output that can be translated to one or more random data bits.

Quantum random number generator

A system and method according to one embodiment are provided for random number generation based on measuring quadrature fluctuations of a single mode thermal state using an optical homodyne detector.

A method and a system for pilot-aided feedforward data recovery are provided. The method and system include a receiver including a strong local oscillator operating in a free running mode independent of a signal light source. The phase relation between the signal light source and the local oscillator source is determined based on quadrature measurements on pilot pulses from the signal light source. Using the above phase relation, information encoded in an incoming signal can be recovered, optionally for use in communication with classical coherent communication protocols and quantum communication protocols.

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Knoxville, TN, United States of America

Bing Qi